0000950170-23-058640 | 10-Q | XBRL Viewer

Fair Value Measurements

9 Months Ended

Sep. 30, 2023

3. Fair Value Measurements

The following table presents the estimated fair values and the related carrying amounts of our financial instruments:


	September 30, 2023				December 31, 2022
	Fair Value		Carrying Value		Fair Value		Carrying Value
(Dollars in millions)
Financial assets:
Investments and other assets	$	1.3	$	1.3	$	1.3	$	1.3
Financial liabilities:
Long-term debt	$	884.2	$	872.9	$	801.1	$	825.3

Investments and other assets – Represents the broker-quoted cash surrender value on universal life insurance policies. This asset is classified as Level 2 in the valuation hierarchy.

Debt – The fair value of our long-term debt is estimated based on the market prices for the same or similar issuances or on the current rates offered to us for debt of the same remaining maturities (Level 2). The fair value of our Credit Facility (as defined in Note 11 – Debt) approximates carrying value due to the variable rate nature of this instrument.

See Note 12 – Derivative Financial Instruments, for the fair value of our derivative financial instruments.

Debt - Schedule of Long-Term Debt Instruments (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Debt	$ 872.9	$ 825.3
Less short-term debt and current maturities of long-term debt	4.0	0.0
Less unamortized debt issuance costs	9.1	7.6
Long-term debt	$ 859.8	817.7
Term Loan B [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	8.34%
Debt, Maturity	2030
Debt	$ 387.7	0.0
7.36 Percent Credit Facility [Member] \| Credit Facility [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate	7.58%
Debt, Maturity	2027
Debt	$ 485.2	325.3
Senior Notes due 2025 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Debt	$ 0.0	$ 500.0

Stock-based Compensation - Schedule of Stock-Based Compensation Expense Recognized (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Stock-based compensation expense recognized:
Less related income tax benefit	$ 1.5	$ 1.2	$ 3.7	$ 3.6
Decrease in net income attributable to Koppers	3.7	2.0	9.3	6.4
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense recognized:
Stock-based compensation expense	$ 5.2	$ 3.2	$ 13.0	$ 10.0

Comprehensive Income (Loss) and Equity - Schedule of Comprehensive Income (Loss) (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Equity [Abstract]
Tax (expense) benefit, unrealized gain (loss) on cash flow hedges	$ (0.6)	$ 4.9	$ (1.0)	$ 21.1
Tax expense, unrecognized pension net loss	$ 0.1	$ 0.1	$ 0.2	$ 0.2

Earnings per Common Share

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Earnings per Common Share

5. Earnings per Common Share

The following table sets forth the computation of basic and diluted earnings per common share:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
(Dollars in millions, except share and per share amounts)
Net income attributable to Koppers	$	26.3	$	19.1	$	76.3	$	49.6
Less: Loss on sale of discontinued operations		0.0		0.0		0.0		(0.5	)
Income from continuing operations attributable to Koppers	$	26.3	$	19.1	$	76.3	$	50.1
Weighted average common shares outstanding (in thousands):
Basic		20,828		20,897		20,838		21,024
Effect of dilutive securities		831		188		708		321
Diluted		21,659		21,085		21,546		21,345
Earnings per common share – continuing operations:
Basic earnings per common share	$	1.27	$	0.91	$	3.66	$	2.38
Diluted earnings per common share		1.22		0.91		3.54		2.35
Other data:
Antidilutive securities excluded from computation of diluted earnings per common share		311		1,088		496		1,075

Pensions and Post-Retirement Benefit Plans - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)	Sep. 30, 2023 Plan
Defined Benefit Plan Disclosure [Line Items]
Premium payment	$ 67.8
Pension settlement loss	$ 20.0
Salaried and Hourly Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of domestic non-qualified defined benefit plans \| Plan		2

New Accounting Pronouncements	9 Months Ended
New Accounting Pronouncements	Sep. 30, 2023
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	2. New Accounting Pronouncements In March 2022, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2022-01, Derivatives and Hedging (Topic 815): Fair Value Hedging—Portfolio Layer Method. This ASU amends and simplifies existing guidance in order to allow companies to more accurately present the economic effects of risk management activities in financial statements. The adoption of this ASU in the first quarter of 2023 did not have a material impact on our financial statements as we principally utilize cash flow hedges.

- Definition

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

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+ Details

Comprehensive Income (Loss) and Equity - Schedule of Changes in Common Stock and Treasury Stock (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Equity [Abstract]
Common Stock, balance at beginning of period	24,838,000	24,505,000	24,547,000	24,027,000
Common Stock, issued for employee stock plans	52,000	18,000	343,000	496,000
Common Stock, balance at end of period	24,889,614	24,523,000	24,889,614	24,523,000
Treasury Stock, balance at beginning of period	(3,965,000)	(3,608,000)	(3,783,901)	(2,931,000)
Treasury Stock, shares repurchased	(102,000)	0	(283,000)	(677,000)
Treasury Stock, balance at end of period	(4,066,548)	(3,608,000)	(4,066,548)	(3,608,000)

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ 26.3	$ 19.1	$ 76.3	$ 49.6

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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-Paragraph 1B
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Derivative Financial Instruments - Summary of Net Currency Units Outstanding (Detail)	Sep. 30, 2023 NZD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 NZD ($)	Dec. 31, 2022 USD ($)
Offsetting [Abstract]
Net currency units outstanding	$ 3,100,000	$ 1,500,000	$ 3,000,000	$ 9,300,000

Property, Plant and Equipment - Property, Plant and Equipment (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Less accumulated depreciation	$ 461.9	$ 462.1
Net	$ 607.8	$ 557.3

Comprehensive Income (Loss) and Equity

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Comprehensive Income (Loss) and Equity

. Comprehensive Income (Loss) and Equity

The following table presents total comprehensive income (loss):


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
(Dollars in millions)
Net income	$	26.2		$	19.0		$	76.8		$	49.4
Changes in other comprehensive income (loss):
Currency translation adjustment		(10.1	)		(20.1	)		(9.6	)		(40.7	)
Unrealized gain (loss) on cash flow hedges, net of tax (expense) benefit of $(0.6), $4.9, $(1.0) and $21.1		1.6			(8.7	)		2.5			(37.4	)
Unrecognized pension net loss, net of tax expense of $0.1, $0.1, $0.2 and $0.2		0.4			0.3			1.0			1.0
Comprehensive income (loss)		18.1			(9.5	)		70.7			(27.7	)
Comprehensive income (loss) attributable to noncontrolling interests		0.0			(0.4	)		0.4			(0.6	)
Comprehensive income (loss) attributable to Koppers	$	18.1		$	(9.1	)	$	70.3		$	(27.1	)

Amounts reclassified from accumulated other comprehensive income (loss) to net income consist of amounts shown for changes in or amortization of unrecognized pension net loss. This component of accumulated other comprehensive income (loss) is included in the computation of net periodic pension cost as disclosed in Note 10 – Pensions and Post-Retirement Benefit Plans. Other amounts reclassified from accumulated other comprehensive income (loss) related to derivative financial instruments, net of tax, were $0.2 million and $5.8 million during the three months ended September 30, 2023 and 2022, respectively, and $2.5 million and $27.0 million during the nine months ended September 30, 2023 and 2022, respectively.

The following table presents changes in common stock and treasury stock:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
(Shares in thousands)
Common Stock:
Balance at beginning of period		24,838			24,505			24,547			24,027
Issued for employee stock plans		52			18			343			496
Balance at end of period		24,890			24,523			24,890			24,523
Treasury Stock:
Balance at beginning of period		(3,965	)		(3,608	)		(3,784	)		(2,931	)
Shares repurchased		(102	)		0			(283	)		(677	)
Balance at end of period		(4,067	)		(3,608	)		(4,067	)		(3,608	)

The following tables present the changes in equity:


(Dollars in millions)	Common Stock		Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Loss			Treasury Stock			Noncontrolling Interests			Total Equity
Balance at June 30, 2023	$	0.2	$	273.7	$	407.3		$	(95.1	)	$	(133.5	)	$	4.0		$	456.6
Net income (loss)		0.0		0.0		26.3			0.0			0.0			(0.1	)		26.2
Dividends ($0.06 per share)		0.0		0.0		(1.2	)		0.0			0.0			0.0			(1.2	)
Issuance of common stock		0.0		1.3		0.0			0.0			0.0			0.0			1.3
Repurchases of common stock		0.0		0.0		0.0			0.0			(3.9	)		0.0			(3.9	)
Employee stock plans		0.0		5.1		0.0			0.0			0.0			0.0			5.1
Other comprehensive (loss) income
Currency translation adjustment		0.0		0.0		0.0			(10.2	)		0.0			0.1			(10.1	)
Unrealized gain on cash flow hedges		0.0		0.0		0.0			1.6			0.0			0.0			1.6
Unrecognized pension net loss		0.0		0.0		0.0			0.4			0.0			0.0			0.4
Balance at September 30, 2023	$	0.2	$	280.1	$	432.4		$	(103.3	)	$	(137.4	)	$	4.0		$	476.0


(Dollars in millions)	Common Stock		Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Loss			Treasury Stock			Noncontrolling Interests			Total Equity
Balance at June 30, 2022	$	0.2	$	257.0	$	329.3		$	(88.7	)	$	(122.5	)	$	3.9		$	379.2
Net income (loss)		0.0		0.0		19.1			0.0			0.0			(0.1	)		19.0
Dividends ($0.05 per share)		0.0		0.0		(1.0	)		0.0			0.0			0.0			(1.0	)
Issuance of common stock		0.0		0.3		0.0			0.0			0.0			0.0			0.3
Employee stock plans		0.0		3.2		0.0			0.0			0.0			0.0			3.2
Other comprehensive (loss) income
Currency translation adjustment		0.0		0.0		0.0			(19.6	)		0.0			(0.3	)		(19.9	)
Unrealized loss on cash flow hedges		0.0		0.0		0.0			(8.7	)		0.0			0.0			(8.7	)
Unrecognized pension net loss		0.0		0.0		0.0			0.3			0.0			0.0			0.3
Balance at September 30, 2022	$	0.2	$	260.5	$	347.4		$	(116.7	)	$	(122.5	)	$	3.5		$	372.4


(Dollars in millions)	Common Stock		Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Loss			Treasury Stock			Noncontrolling Interests			Total Equity
Balance at December 31, 2022	$	0.2	$	263.9	$	360.2		$	(97.3	)	$	(127.6	)	$	3.6		$	403.0
Net income		0.0		0.0		76.3			0.0			0.0			0.5			76.8
Dividends ($0.18 per share)		0.0		0.0		(4.1	)		0.0			0.0			0.0			(4.1	)
Issuance of common stock		0.0		3.2		0.0			0.0			0.0			0.0			3.2
Repurchases of common stock		0.0		0.0		0.0			0.0			(9.8	)		0.0			(9.8	)
Employee stock plans		0.0		13.0		0.0			0.0			0.0			0.0			13.0
Other comprehensive (loss) income
Currency translation adjustment		0.0		0.0		0.0			(9.5	)		0.0			(0.1	)		(9.6	)
Unrealized gain on cash flow hedges		0.0		0.0		0.0			2.5			0.0			0.0			2.5
Unrecognized pension net loss		0.0		0.0		0.0			1.0			0.0			0.0			1.0
Balance at September 30, 2023	$	0.2	$	280.1	$	432.4		$	(103.3	)	$	(137.4	)	$	4.0		$	476.0


(Dollars in millions)	Common Stock		Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Loss			Treasury Stock			Noncontrolling Interests			Total Equity
Balance at December 31, 2021	$	0.2	$	249.5	$	300.9		$	(40.0	)	$	(104.0	)	$	4.2		$	410.8
Net income (loss)		0.0		0.0		49.6			0.0			0.0			(0.2	)		49.4
Dividends ($0.15 per share)		0.0		0.0		(3.2	)		0.0			0.0			0.0			(3.2	)
Issuance of common stock		0.0		0.9		0.0			0.0			0.0			0.0			0.9
Repurchases of common stock		0.0		0.0		0.0			0.0			(18.5	)		0.0			(18.5	)
Employee stock plans		0.0		10.1		0.0			0.0			0.0			0.0			10.1
Other comprehensive (loss) income
Currency translation adjustment		0.0		0.0		0.0			(40.2	)		0.0			(0.6	)		(40.8	)
Unrealized loss on cash flow hedges		0.0		0.0		0.0			(37.4	)		0.0			0.0			(37.4	)
Unrecognized pension net loss		0.0		0.0		0.0			1.0			0.0			0.0			1.0
Balance at September 30, 2022	$	0.2	$	260.5	$	347.4		$	(116.7	)	$	(122.5	)	$	3.5		$	372.4

On November 2, 2023, we declared a quarterly dividend of $0.06 per common share, payable on December 11, 2023 to shareholders of record as of November 24, 2023.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (d)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Stock-based Compensation

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Stock-based Compensation

6. Stock-based Compensation

The board of directors granted restricted stock units and performance stock units (collectively, the stock units) to certain employee participants in January 2023. No stock options were granted in 2023. Starting in 2023, most grants of restricted stock units vest in three years. Performance stock units have vesting based upon either a performance condition or a market condition. Performance stock units granted with a performance condition have a cumulative three-year performance objective based on adjusted EBITDA (see Note 7 – Segment Information). For performance stock units granted with a market condition, the applicable objective is based on our total shareholder return relative to the Standard & Poor’s SmallCap 600 Materials Index and has multi-year performance objectives. Both types of performance stock units have a three-year period for vesting, if the applicable performance objectives are achieved.

The number of performance stock units granted represents the target award and participants have the ability to earn between zero and 200 percent of the target award based upon actual performance. If minimum performance criteria are not achieved, no performance stock units will vest. For the awards granted in January 2023, target shares for units with market conditions were 78,411 and target shares for units with performance conditions were 188,238.

We calculated the fair value of the restricted stock units and performance stock units with a performance condition using the market price of the underlying common stock on the date of grant. We calculated the fair value of the performance stock units with a market condition on the date of grant using a Monte Carlo valuation model and the assumptions listed below:


	January 2023 Grant
Grant date price per share of performance award	$	29.01
Expected volatility		66.30	%
Risk-free interest rate		4.11	%
Look-back period in years		3.00
Grant date fair value per share	$	39.51

The following table shows a summary of the status and activity of non-vested stock units:


	Restricted Stock Units			Performance Stock Units			Total Stock Units			Weighted Average Grant Date Fair Value per Unit
Non-vested at December 31, 2022		524,612			237,032			761,644		$	32.40
Granted		232,994			267,073			500,067		$	30.76
Credited from dividends		3,469			1,594			5,063		$	26.89
Vested		(219,479	)		0			(219,479	)	$	26.37
Forfeited		(15,961	)		(6,414	)		(22,375	)	$	32.01
Non-vested at September 30, 2023		525,635			499,285			1,024,920		$	32.85

The following table shows a summary of the status and activity of stock options:


	Options			Weighted Average Exercise Price per Option		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in millions)
Outstanding at December 31, 2022		1,122,136		$	27.05
Exercised		(101,938	)	$	21.80
Expired		(50,031	)	$	42.16
Outstanding at September 30, 2023		970,167		$	26.83		4.42	$	12.9
Exercisable at September 30, 2023		808,691		$	26.55		3.81	$	11.1

Stock Compensation Expense

The following table presents total stock-based compensation expense recognized:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
(Dollars in millions)
Stock-based compensation expense recognized:
Selling, general and administrative expenses	$	5.2	$	3.2	$	13.0	$	10.0
Less related income tax benefit		1.5		1.2		3.7		3.6
Decrease in net income attributable to Koppers	$	3.7	$	2.0	$	9.3	$	6.4

Condensed Consolidated Balance Sheet - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Assets
Cash and cash equivalents	$ 53.5	$ 33.3
Accounts receivable, net of allowance of $3.4 and $3.5	241.7	215.7
Inventories, net	369.6	355.7
Derivative contracts	4.7	3.1
Other current assets	30.0	29.0
Total current assets	699.5	636.8
Property, plant and equipment, net of accumulated depreciation of $461.9 and $462.1	607.8	557.3
Operating lease right-of-use assets	84.3	86.3
Goodwill	292.9	294.0
Intangible assets, net	105.2	116.1
Deferred tax assets	10.7	11.7
Other assets	9.8	9.2
Total assets	1,810.2	1,711.4
Liabilities
Accounts payable	205.6	207.4
Accrued liabilities	80.9	96.1
Current operating lease liabilities	22.4	20.5
Current maturities of long-term debt	4.0	0.0
Total current liabilities	312.9	324.0
Long-term debt	859.8	817.7
Accrued postretirement benefits	34.9	34.7
Deferred tax liabilities	22.9	21.5
Operating lease liabilities	61.8	66.3
Other long-term liabilities	41.9	44.2
Total liabilities	1,334.2	1,308.4
Commitments and contingent liabilities (Note 13)
Equity
Senior Convertible Preferred Stock, $0.01 par value per share; 10,000,000 shares authorized; no shares issued	0.0	0.0
Common Stock, $0.01 par value per share; 80,000,000 shares authorized; 24,889,614 and 24,547,000 shares issued	0.2	0.2
Additional paid-in capital	280.1	263.9
Retained earnings	432.4	360.2
Accumulated other comprehensive loss	(103.3)	(97.3)
Treasury stock, at cost, 4,066,548 and 3,783,901 shares	(137.4)	(127.6)
Total Koppers shareholders’ equity	472.0	399.4
Noncontrolling interests	4.0	3.6
Total equity	476.0	403.0
Total liabilities and equity	$ 1,810.2	$ 1,711.4

Debt (Tables)

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Schedule of Long-Term Debt Instruments

The following table summarizes debt:


	Weighted Average Interest Rate			Maturity	September 30, 2023		December 31, 2022
(Dollars in millions)
Credit Facility		7.58	%	2027	$	485.2	$	325.3
Term Loan B		8.34	%	2030		387.7		0.0
Senior Notes due 2025	-			-		0.0		500.0
Debt					$	872.9	$	825.3
Less short-term debt and current maturities of long-term debt						4.0		0.0
Less unamortized debt issuance costs						9.1		7.6
Long-term debt					$	859.8	$	817.7

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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+ Details

New Accounting Pronouncements - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2023
Accounting Changes and Error Corrections [Abstract]
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption period	ASU in the first quarter of 2023
Change in accounting principle, accounting standards update, immaterial effect [true false]	true
Accounting standards update [extensible enumeration]	us-gaap:AccountingStandardsUpdate202201Member

- Definition

Indicates amendment to accounting standards.

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-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483443/250-10-50-1

+ Details

- Definition

Indicates (true false) whether accounting standards update was adopted.

+ References

+ Details

Insider Trading Arrangements	9 Months Ended
Insider Trading Arrangements	Sep. 30, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Inventories, Net

9 Months Ended

Sep. 30, 2023

Inventory Disclosure [Abstract]

Inventories, Net

9. Inventories, net


	September 30, 2023		December 31, 2022
(Dollars in millions)
Raw materials	$	329.2	$	318.5
Work in process		17.8		10.2
Finished goods		129.4		130.4
	$	476.4	$	459.1
Less revaluation to LIFO		106.8		103.4
Net	$	369.6	$	355.7

Derivative Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Fair Value of Outstanding Derivative contracts

The fair value of the outstanding derivative contracts recorded in the balance sheet are as follows:


	September 30, 2023
	Copper Swap Contracts			Foreign Currency Forward Contracts			Interest Rate Swap Contracts		Total
(Dollars in millions)
Derivative contracts	$	0.3		$	0.2		$	4.2	$	4.7
Other assets		0.2			0.0			2.7		2.9
Accrued liabilities		(0.9	)		(0.1	)		0.0		(1.0	)
Other long-term liabilities		(0.1	)		0.0			0.0		(0.1	)
Net asset (liability) on balance sheet	$	(0.5	)	$	0.1		$	6.9	$	6.5
Accumulated other comprehensive gain (loss), net of tax	$	(0.7	)	$	0.0		$	5.2	$	4.5


	December 31, 2022
	Copper Swap Contracts			Foreign Currency Forward Contracts			Interest Rate Swap Contracts		Total
(Dollars in millions)
Derivative contracts	$	3.0		$	0.1		$	0.0	$	3.1
Other assets		0.4			0.0			0.0		0.4
Accrued liabilities		(0.3	)		(0.1	)		0.0		(0.4	)
Net asset on balance sheet	$	3.1		$	0.0		$	0.0	$	3.1
Accumulated other comprehensive gain, net of tax	$	1.8		$	0.0		$	0.0	$	1.8

Schedule of Outstanding Copper Swap Contracts

As of the periods presented, we had outstanding copper swap contracts of the following amounts:


	Units Outstanding (in Pounds)				Net Fair Value - (Liability) Asset
	September 30, 2023		December 31, 2022		September 30, 2023			December 31, 2022
(Amounts in millions)
Cash flow hedges		35.3		21.3	$	(1.0	)	$	2.5
Contracts where hedge accounting was not elected		11.0		6.0		0.5			0.6
Total		46.3		27.3	$	(0.5	)	$	3.1

Schedule of Unrealized Loss from Contract Where Hedge Accounting Was Not Elected

The unrealized loss from copper swaps contracts where hedge accounting was not elected is as follows:


	Three Months Ended September 30,					Nine Months Ended September 30,
	2023		2022			2023		2022
(Dollars in millions)
(Loss) from contracts where hedge accounting was not elected	$	0.0	$	(1.9	)	$	0.0	$	(9.0	)

Summary of Net Currency Units Outstanding

The net currency units outstanding for contracts were:


	September 30, 2023		December 31, 2022
(In millions)
Australian Dollars		AUD 3.1		AUD 3.0
United States Dollars		USD 1.5		USD 9.3

Plant Closure and Divestitures - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Restructuring Cost and Reserve [Line Items]
Gain on sale	$ 0.0	$ 0.0	$ 1.8	$ 2.5

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2023	Oct. 31, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Trading Symbol	KOP
Entity Registrant Name	KOPPERS HOLDINGS INC.
Entity Central Index Key	0001315257
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		20,823,066
Title of 12(b) Security	Common Stock
Security Exchange Name	NYSE
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity File Number	1-32737
Entity Tax Identification Number	20-1878963
Entity Address, Address Line One	436 Seventh Avenue
Entity Address, City or Town	Pittsburgh
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	15219
City Area Code	412
Local Phone Number	227-2001
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	PA

Comprehensive Income (Loss) and Equity (Tables)

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Schedule of Comprehensive Income (Loss)

The following table presents total comprehensive income (loss):


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
(Dollars in millions)
Net income	$	26.2		$	19.0		$	76.8		$	49.4
Changes in other comprehensive income (loss):
Currency translation adjustment		(10.1	)		(20.1	)		(9.6	)		(40.7	)
Unrealized gain (loss) on cash flow hedges, net of tax (expense) benefit of $(0.6), $4.9, $(1.0) and $21.1		1.6			(8.7	)		2.5			(37.4	)
Unrecognized pension net loss, net of tax expense of $0.1, $0.1, $0.2 and $0.2		0.4			0.3			1.0			1.0
Comprehensive income (loss)		18.1			(9.5	)		70.7			(27.7	)
Comprehensive income (loss) attributable to noncontrolling interests		0.0			(0.4	)		0.4			(0.6	)
Comprehensive income (loss) attributable to Koppers	$	18.1		$	(9.1	)	$	70.3		$	(27.1	)

Schedule of Changes in Common Stock and Treasury Stock

The following table presents changes in common stock and treasury stock:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
(Shares in thousands)
Common Stock:
Balance at beginning of period		24,838			24,505			24,547			24,027
Issued for employee stock plans		52			18			343			496
Balance at end of period		24,890			24,523			24,890			24,523
Treasury Stock:
Balance at beginning of period		(3,965	)		(3,608	)		(3,784	)		(2,931	)
Shares repurchased		(102	)		0			(283	)		(677	)
Balance at end of period		(4,067	)		(3,608	)		(4,067	)		(3,608	)

Schedule of Changes in Equity

The following tables present the changes in equity:


(Dollars in millions)	Common Stock		Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Loss			Treasury Stock			Noncontrolling Interests			Total Equity
Balance at June 30, 2023	$	0.2	$	273.7	$	407.3		$	(95.1	)	$	(133.5	)	$	4.0		$	456.6
Net income (loss)		0.0		0.0		26.3			0.0			0.0			(0.1	)		26.2
Dividends ($0.06 per share)		0.0		0.0		(1.2	)		0.0			0.0			0.0			(1.2	)
Issuance of common stock		0.0		1.3		0.0			0.0			0.0			0.0			1.3
Repurchases of common stock		0.0		0.0		0.0			0.0			(3.9	)		0.0			(3.9	)
Employee stock plans		0.0		5.1		0.0			0.0			0.0			0.0			5.1
Other comprehensive (loss) income
Currency translation adjustment		0.0		0.0		0.0			(10.2	)		0.0			0.1			(10.1	)
Unrealized gain on cash flow hedges		0.0		0.0		0.0			1.6			0.0			0.0			1.6
Unrecognized pension net loss		0.0		0.0		0.0			0.4			0.0			0.0			0.4
Balance at September 30, 2023	$	0.2	$	280.1	$	432.4		$	(103.3	)	$	(137.4	)	$	4.0		$	476.0


(Dollars in millions)	Common Stock		Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Loss			Treasury Stock			Noncontrolling Interests			Total Equity
Balance at June 30, 2022	$	0.2	$	257.0	$	329.3		$	(88.7	)	$	(122.5	)	$	3.9		$	379.2
Net income (loss)		0.0		0.0		19.1			0.0			0.0			(0.1	)		19.0
Dividends ($0.05 per share)		0.0		0.0		(1.0	)		0.0			0.0			0.0			(1.0	)
Issuance of common stock		0.0		0.3		0.0			0.0			0.0			0.0			0.3
Employee stock plans		0.0		3.2		0.0			0.0			0.0			0.0			3.2
Other comprehensive (loss) income
Currency translation adjustment		0.0		0.0		0.0			(19.6	)		0.0			(0.3	)		(19.9	)
Unrealized loss on cash flow hedges		0.0		0.0		0.0			(8.7	)		0.0			0.0			(8.7	)
Unrecognized pension net loss		0.0		0.0		0.0			0.3			0.0			0.0			0.3
Balance at September 30, 2022	$	0.2	$	260.5	$	347.4		$	(116.7	)	$	(122.5	)	$	3.5		$	372.4


(Dollars in millions)	Common Stock		Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Loss			Treasury Stock			Noncontrolling Interests			Total Equity
Balance at December 31, 2022	$	0.2	$	263.9	$	360.2		$	(97.3	)	$	(127.6	)	$	3.6		$	403.0
Net income		0.0		0.0		76.3			0.0			0.0			0.5			76.8
Dividends ($0.18 per share)		0.0		0.0		(4.1	)		0.0			0.0			0.0			(4.1	)
Issuance of common stock		0.0		3.2		0.0			0.0			0.0			0.0			3.2
Repurchases of common stock		0.0		0.0		0.0			0.0			(9.8	)		0.0			(9.8	)
Employee stock plans		0.0		13.0		0.0			0.0			0.0			0.0			13.0
Other comprehensive (loss) income
Currency translation adjustment		0.0		0.0		0.0			(9.5	)		0.0			(0.1	)		(9.6	)
Unrealized gain on cash flow hedges		0.0		0.0		0.0			2.5			0.0			0.0			2.5
Unrecognized pension net loss		0.0		0.0		0.0			1.0			0.0			0.0			1.0
Balance at September 30, 2023	$	0.2	$	280.1	$	432.4		$	(103.3	)	$	(137.4	)	$	4.0		$	476.0


(Dollars in millions)	Common Stock		Additional Paid-In Capital		Retained Earnings			Accumulated Other Comprehensive Loss			Treasury Stock			Noncontrolling Interests			Total Equity
Balance at December 31, 2021	$	0.2	$	249.5	$	300.9		$	(40.0	)	$	(104.0	)	$	4.2		$	410.8
Net income (loss)		0.0		0.0		49.6			0.0			0.0			(0.2	)		49.4
Dividends ($0.15 per share)		0.0		0.0		(3.2	)		0.0			0.0			0.0			(3.2	)
Issuance of common stock		0.0		0.9		0.0			0.0			0.0			0.0			0.9
Repurchases of common stock		0.0		0.0		0.0			0.0			(18.5	)		0.0			(18.5	)
Employee stock plans		0.0		10.1		0.0			0.0			0.0			0.0			10.1
Other comprehensive (loss) income
Currency translation adjustment		0.0		0.0		0.0			(40.2	)		0.0			(0.6	)		(40.8	)
Unrealized loss on cash flow hedges		0.0		0.0		0.0			(37.4	)		0.0			0.0			(37.4	)
Unrecognized pension net loss		0.0		0.0		0.0			1.0			0.0			0.0			1.0
Balance at September 30, 2022	$	0.2	$	260.5	$	347.4		$	(116.7	)	$	(122.5	)	$	3.5		$	372.4

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(27))
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-Publisher FASB
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+ Details

Comprehensive Income (Loss) and Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Nov. 02, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income Loss [Line Items]
Income (loss) related to derivative instrument, net of tax		$ 0.2	$ 5.8	$ 2.5	$ 27.0
Subsequent Event [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Quarterly dividend declared per common share	$ 0.06
Quarterly dividend, declared date	Nov. 02, 2023
Quarterly dividend, payable date	Dec. 11, 2023
Quarterly dividend, payable date of record	Nov. 24, 2023

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Commitments and Contingent Liabilities - Additional Information (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) Case Site Plant State Plaintiff Party	Dec. 31, 2022 USD ($) Case Plaintiff	Dec. 31, 2021 USD ($)
Loss Contingencies [Line Items]
Number of states with new claims filed \| State	2
Number of plaintiffs \| Plaintiff	51	51
Environmental remediation and regulation liability	$ 10,500,000	$ 10,900,000	$ 10,700,000
Environmental Loss Contingency, Statement of Financial Position [Extensible Enumeration]	Liabilities, Current
Accrued liability for environmental matters, current	$ 2,400,000	$ 2,500,000
Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration]	Liabilities, Current	Liabilities, Current
Portland Harbor and Newark Bay CERCLA sites [Member]
Loss Contingencies [Line Items]
Costs of participating in PRP group	$ 4,000,000
Beazer East [Member]
Loss Contingencies [Line Items]
Sites listed on National Priorities List \| Site	1
Compensatory Damages [Member]
Loss Contingencies [Line Items]
Number of cases \| Case	27
Punitive Damages [Member]
Loss Contingencies [Line Items]
Number of cases \| Case	24
Coal Tar Pitch Cases [Member]
Loss Contingencies [Line Items]
Number of cases \| Case	27	27
Reserve for legal proceedings	$ 0
Pennsylvania [Member]
Loss Contingencies [Line Items]
Number of cases \| Case	26
Pennsylvania [Member] \| Coal Tar Pitch Cases [Member]
Loss Contingencies [Line Items]
Number of cases \| Case	26
Sweetwater, Tennessee [Member] \| Coal Tar Pitch Cases [Member]
Loss Contingencies [Line Items]
Number of cases \| Case	1
Compensatory damages	$ 15,000,000.0
Oregon [Member]
Loss Contingencies [Line Items]
Number of potential responsible parties \| Party	80
Net present value of selected remedy estimation	$ 1,100,000,000
Undiscounted cost of selected remedy estimation	1,700,000,000
United States [Member]
Loss Contingencies [Line Items]
Environmental remediation and regulation liability	$ 3,800,000
United States [Member] \| Performance Chemicals [Member]
Loss Contingencies [Line Items]
Number of plant sites \| Plant	2
United States [Member] \| Utility and Industrial Products [Member]
Loss Contingencies [Line Items]
Number of plant sites \| Plant	1
Australia [Member] \| Performance Chemicals [Member]
Loss Contingencies [Line Items]
Environmental remediation and regulation liability	$ 1,200,000

Pensions and Post-Retirement Benefit Plans

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Pensions and Post-Retirement Benefit Plans

10. Pensions and Post-Retirement Benefit Plans

We maintain a number of defined benefit and defined contribution plans to provide retirement benefits for employees in the United States, as well as employees outside the United States.

In the United States, all qualified and two of the non-qualified defined benefit pension plans for salaried and hourly employees have been closed to new participants and have been frozen. Accordingly, these pension plans no longer accrue additional years of service or recognize future increases in compensation for benefit purposes.

In connection with our defined benefit pension plan in the United Kingdom, in 2021, we entered into a buy-in bulk annuity insurance policy in exchange for a premium payment of $67.8 million, which is subject to adjustment as a result of subsequent data cleansing activities. Under the terms of this buy-in insurance policy, the insurer is liable to pay the benefits of the plan, but the plan still retains full legal responsibility to pay the benefits to members using the insurance payments. The buy-in policy will be treated as a plan asset going forward until such time as the buy-in policy is converted to a buy-out policy, which is when individual insurance policies will be assigned to each member of the plan and the plan will no longer have legal responsibility to pay the benefits to the members. The data cleansing effort has been substantially completed and we expect to recognize a pre-tax pension settlement loss of approximately $20 million upon the pension obligation becoming irrevocably settled sometime in 2024.

The following table provides the components of net periodic benefit cost for the pension plans:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
(Dollars in millions)
Service cost	$	0.4		$	0.3		$	1.2		$	0.9
Interest cost		2.1			1.4			6.2			4.3
Expected return on plan assets		(1.7	)		(1.9	)		(5.2	)		(5.8	)
Amortization of net loss		0.5			0.4			1.6			1.3
Net periodic benefit cost	$	1.3		$	0.2		$	3.8		$	0.7
Defined contribution plan expense	$	3.2		$	2.2		$	8.0		$	7.0

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480794/715-70-50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
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-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480482/715-20-55-17

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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-Name Accounting Standards Codification
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480126/715-20-S99-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
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-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480266/715-60-50-3

+ Details

Derivative Financial Instruments - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Derivative [Line Items]
Maximum period hedged in cash flow hedge	36 months
Unrealized gains, reclassification period	12 months
Interest Rate Swaps [Member]
Derivative [Line Items]
Unrealized gains, net of tax, expected to be reclassified from other comprehensive income into earnings	$ 3.2
Commodity Price Hedging [Member]
Derivative [Line Items]
Unrealized gains, net of tax, expected to be reclassified from other comprehensive income into earnings	$ 0.6

Derivative Financial Instruments

9 Months Ended

Sep. 30, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments

12. Derivative Financial Instruments

We utilize derivative instruments to manage exposures to risks that have been identified, measured and are capable of being mitigated. The primary risks that we manage by using derivative instruments are commodity price risk associated with copper, foreign currency exchange risk, principally the U.S. dollar and Australian dollar, and interest rate risk associated with variable rate borrowings. Generally, we enter into master netting arrangements with the counterparties and offset net derivative positions with the same counterparties. Currently, our agreements do not require cash collateral.

The Company recognizes all derivative instruments as either assets or liabilities at fair value on the balance sheet. The derivative instruments are classified as current or noncurrent based upon the expected timing of cash flows and are subject to offset under our master netting arrangements. A derivative instrument's fair value is determined using significant other observable inputs, a Level 2 fair value measurement.

For derivative instruments that are designated and qualify as cash flow hedges, the effective portion of the gain or loss on the derivative is reported as a component of other comprehensive income and is reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Gains and losses on the derivative instruments representing hedge ineffectiveness are recognized in current earnings.

Swap contracts on copper are used to manage the price risk associated with forecasted purchases of materials used in our manufacturing processes. Generally, we will not hedge cash flow exposures for durations longer than 36 months and we have hedged certain volumes of copper through the end of 2024. We designate certain of our commodity swaps as cash flow hedges of forecasted purchases of commodities. For those commodity swaps where hedge accounting is not elected, the fair value of the commodity swap is recognized as an asset or liability on the condensed consolidated balance sheet and the related unrealized gain or loss on the derivative is reported in current earnings. These amounts are classified in cost of sales in the condensed consolidated statement of operations.

We enter into foreign currency forward contracts to manage foreign currency risk associated with our receivable and payable balances in addition to foreign-denominated sales. The fair value associated with forward contracts related to foreign currency that are not designated as hedges are immediately charged to earnings. These amounts are classified in cost of sales in the condensed consolidated statement of operations.

We enter into interest rate swaps to effectively convert portions of our variable interest debt into fixed rate debt to add stability to interest expense and to manage our exposure to interest rate movements. We designate our interest rate swaps as cash flow hedges on interest payments.

See Note 4 – Comprehensive Income (Loss) and Equity, for amounts recorded in other comprehensive income (loss) and for amounts reclassified from accumulated other comprehensive income (loss) into net income.

The fair value of the outstanding derivative contracts recorded in the balance sheet are as follows:


	September 30, 2023
	Copper Swap Contracts			Foreign Currency Forward Contracts			Interest Rate Swap Contracts		Total
(Dollars in millions)
Derivative contracts	$	0.3		$	0.2		$	4.2	$	4.7
Other assets		0.2			0.0			2.7		2.9
Accrued liabilities		(0.9	)		(0.1	)		0.0		(1.0	)
Other long-term liabilities		(0.1	)		0.0			0.0		(0.1	)
Net asset (liability) on balance sheet	$	(0.5	)	$	0.1		$	6.9	$	6.5
Accumulated other comprehensive gain (loss), net of tax	$	(0.7	)	$	0.0		$	5.2	$	4.5


	December 31, 2022
	Copper Swap Contracts			Foreign Currency Forward Contracts			Interest Rate Swap Contracts		Total
(Dollars in millions)
Derivative contracts	$	3.0		$	0.1		$	0.0	$	3.1
Other assets		0.4			0.0			0.0		0.4
Accrued liabilities		(0.3	)		(0.1	)		0.0		(0.4	)
Net asset on balance sheet	$	3.1		$	0.0		$	0.0	$	3.1
Accumulated other comprehensive gain, net of tax	$	1.8		$	0.0		$	0.0	$	1.8

Over the next twelve months, we estimate unrealized losses of $0.6 million for commodity price hedging as well as unrealized gains of $3.2 million for interest rate swaps will be reclassified from accumulated other comprehensive income into earnings.

Copper Swap Contracts

As of the periods presented, we had outstanding copper swap contracts of the following amounts:


	Units Outstanding (in Pounds)				Net Fair Value - (Liability) Asset
	September 30, 2023		December 31, 2022		September 30, 2023			December 31, 2022
(Amounts in millions)
Cash flow hedges		35.3		21.3	$	(1.0	)	$	2.5
Contracts where hedge accounting was not elected		11.0		6.0		0.5			0.6
Total		46.3		27.3	$	(0.5	)	$	3.1

The unrealized loss from copper swaps contracts where hedge accounting was not elected is as follows:


	Three Months Ended September 30,					Nine Months Ended September 30,
	2023		2022			2023		2022
(Dollars in millions)
(Loss) from contracts where hedge accounting was not elected	$	0.0	$	(1.9	)	$	0.0	$	(9.0	)

Foreign Currency Forward Contracts

The net currency units outstanding for contracts were:


	September 30, 2023		December 31, 2022
(In millions)
Australian Dollars		AUD 3.1		AUD 3.0
United States Dollars		USD 1.5		USD 9.3

Interest Rate Swap Contracts

See Note 11 – Debt for discussion of the interest rate swap agreements, which effectively convert the variable rate to a fixed rate for a portion of our variable rate debt. The interest rate swaps have been designated as cash flow hedges and involve the receipt of variable amounts from a counterparty in exchange for us making fixed rate payments over the life of the agreements without exchange of the underlying notional amount.

Commitments and Contingent Liabilities (Tables)

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Changes in Accrued Liability for Environmental Matters

The following table reflects changes in the accrual for environmental remediation. A total of $2.4 million and $2.5 million are classified as current liabilities as of September 30, 2023 and December 31, 2022, respectively.


	Period ended
	September 30, 2023			December 31, 2022
(Dollars in millions)
Balance at beginning of period	$	10.9		$	10.7
Expense		0.1			1.6
Cash expenditures		(0.3	)		(1.1	)
Currency translation		(0.2	)		(0.3	)
Balance at end of period	$	10.5		$	10.9

Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2023

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary of Status and Activity of Non-Vested Stock Units

The following table shows a summary of the status and activity of non-vested stock units:


	Restricted Stock Units			Performance Stock Units			Total Stock Units			Weighted Average Grant Date Fair Value per Unit
Non-vested at December 31, 2022		524,612			237,032			761,644		$	32.40
Granted		232,994			267,073			500,067		$	30.76
Credited from dividends		3,469			1,594			5,063		$	26.89
Vested		(219,479	)		0			(219,479	)	$	26.37
Forfeited		(15,961	)		(6,414	)		(22,375	)	$	32.01
Non-vested at September 30, 2023		525,635			499,285			1,024,920		$	32.85

Summary of Status and Activity of Stock Options

The following table shows a summary of the status and activity of stock options:


	Options			Weighted Average Exercise Price per Option		Weighted Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in millions)
Outstanding at December 31, 2022		1,122,136		$	27.05
Exercised		(101,938	)	$	21.80
Expired		(50,031	)	$	42.16
Outstanding at September 30, 2023		970,167		$	26.83		4.42	$	12.9
Exercisable at September 30, 2023		808,691		$	26.55		3.81	$	11.1

Schedule of Stock-based Compensation Expense Recognized

The following table presents total stock-based compensation expense recognized:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
(Dollars in millions)
Stock-based compensation expense recognized:
Selling, general and administrative expenses	$	5.2	$	3.2	$	13.0	$	10.0
Less related income tax benefit		1.5		1.2		3.7		3.6
Decrease in net income attributable to Koppers	$	3.7	$	2.0	$	9.3	$	6.4

Performance Stock Units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock Options And Performance Award Fair Value Assumptions


	January 2023 Grant
Grant date price per share of performance award	$	29.01
Expected volatility		66.30	%
Risk-free interest rate		4.11	%
Look-back period in years		3.00
Grant date fair value per share	$	39.51

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
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+ Details

Segment Information (Tables)

9 Months Ended

Sep. 30, 2023

Segment Reporting [Abstract]

Schedule of Segment Revenues for Significant Product Lines

The following table sets forth revenues for significant product lines, net of all intersegment transactions, for our segments:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
(Dollars in millions)
Railroad and Utility Products and Services:
Railroad treated products	$	142.7	$	120.6	$	408.7	$	348.2
Utility poles		68.9		63.0		203.4		178.7
Railroad infrastructure services		16.0		16.3		49.8		46.8
Rail joints		6.4		7.8		19.6		21.6
Total Railroad and Utility Products and Services		234.0		207.7		681.5		595.3
Performance Chemicals:
Wood preservative products		166.9		148.3		470.4		419.2
Other products		12.5		4.8		36.8		19.9
Total Performance Chemicals		179.4		153.1		507.2		439.1
Carbon Materials and Chemicals:
Pitch and related products		83.9		109.6		288.6		270.0
Phthalic anhydride and other chemicals		19.1		31.6		59.8		85.0
Carbon black feedstock and distillates		18.3		17.2		56.8		56.9
Naphthalene		7.0		9.1		22.3		26.1
Other products		8.7		7.8		24.8		25.5
Total Carbon Materials and Chemicals		137.0		175.3		452.3		463.5
Total	$	550.4	$	536.1	$	1,641.0	$	1,497.9
Intersegment revenues:
Performance Chemicals	$	8.4	$	6.8	$	21.2	$	16.7
Carbon Materials and Chemicals		24.3		19.9		66.5		57.4
Total	$	32.7	$	26.7	$	87.7	$	74.1

Summary of Results of Segment Operations

The following table sets forth certain operating data, net of all intersegment transactions, for our segments:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
(Dollars in millions)
Depreciation and amortization expense:
Railroad and Utility Products and Services	$	6.2		$	5.6		$	17.9		$	16.5
Performance Chemicals		3.5			3.8			10.5			11.5
Carbon Materials and Chemicals		4.6			7.5			14.3			16.5
Total	$	14.3		$	16.9		$	42.7		$	44.5
Adjusted EBITDA:
Railroad and Utility Products and Services	$	25.1		$	15.5		$	63.2		$	40.3
Performance Chemicals		35.2			16.7			93.8			57.9
Carbon Materials and Chemicals		10.4			36.6			45.5			77.8
Items excluded from the determination of segment profit:
LIFO expense(1)		(2.8	)		(6.1	)		(3.3	)		(12.9	)
Impairment, restructuring and plant closure costs		(0.1	)		(0.3	)		(0.1	)		(0.2	)
Gain on sale of assets		0.0			0.0			1.8			2.5
Mark-to-market commodity hedging losses		0.0			(1.9	)		0.0			(9.0	)
Interest expense		(19.0	)		(11.4	)		(53.3	)		(32.3	)
Depreciation and amortization		(14.3	)		(16.9	)		(42.7	)		(44.5	)
Income tax provision		(8.3	)		(13.2	)		(28.1	)		(29.7	)
Discontinued operations		0.0			0.0			0.0			(0.5	)
Net income	$	26.2		$	19.0		$	76.8		$	49.4

(1)

The LIFO expense adjustment removes the entire impact of LIFO and effectively reflects the results as if we were on a FIFO inventory basis.

Summary of Assets and Goodwill by Segments

The following table sets forth assets and goodwill allocated to each of our segments:


	September 30, 2023		December 31, 2022
(Dollars in millions)
Segment assets:
Railroad and Utility Products and Services	$	739.3	$	660.8
Performance Chemicals		521.5		516.9
Carbon Materials and Chemicals		515.0		500.5
All other		34.4		33.2
Total	$	1,810.2	$	1,711.4
Goodwill:
Railroad and Utility Products and Services	$	120.4	$	120.6
Performance Chemicals		172.5		173.4
Total	$	292.9	$	294.0

Income Taxes

9 Months Ended

Sep. 30, 2023

Income Tax Disclosure [Abstract]

Income Taxes

8. Income Taxes

Effective Tax Rate

The income tax provision for interim periods is comprised of an estimated annual effective income tax rate applied to current year ordinary income and tax associated with discrete items. These discrete items generally relate to excess stock compensation deductions, changes in tax laws, adjustments to unrecognized tax benefits and changes of estimated tax liability to the actual liability determined upon filing income tax returns. To determine the annual effective tax rate, management is required to make estimates of annual pretax income in each domestic and foreign jurisdiction in which we conduct business. Entities that have historical pre-tax losses and current year estimated pre-tax losses that are not projected to generate a future benefit are excluded from the estimated annual effective income tax rate.

The estimated annual effective income tax rate differs from the U.S. federal statutory tax rate due to:


	September 30,
	2023			2022
Federal income tax rate		21.0	%		21.0	%
Foreign earnings taxed at different rates		4.8			6.8
Nondeductible expenses		1.4			1.6
State income taxes, net of federal tax benefit		1.3			0.6
Change in tax contingency reserves		0.1			0.1
GILTI inclusion, net of foreign tax credits		(0.3	)		0.1
Interest expense deduction limitation		0.0			5.9
Estimated annual effective income tax rate		28.3	%		36.1	%

Income taxes as a percentage of pretax income were 24.1 and 41.0 percent for the three months ended September 30, 2023 and 2022, respectively, and 26.8 and 37.3 percent for the nine months ended September 30, 2023 and 2022, respectively. These percentages for the three and nine months ended September 30, 2023 were lower than the estimated annual effective income tax rate due to adjustments to our 2022 US income tax provision primarily resulting from a July 2023 IRS notice that clarified existing tax regulations. For the three months ended September 30, 2022, the actual percentage was higher than the estimated annual effective income tax rate due to additional tax expense recognized in the quarter as a result of increases in the estimated annual effective income tax rate from the prior period. For the nine months ended September 30, 2022, the actual percentage was higher than the estimated annual effective income tax rate due to forecasted pre-tax losses of certain foreign subsidiaries not expected to generate a future tax benefit.

During the year, management regularly updates estimates of pre-tax income and income tax expense based on changes in pre-tax income projections by taxable jurisdiction, repatriation of foreign earnings, unrecognized tax benefits and other tax matters. To the extent that actual results vary from these estimates, the actual annual effective income tax rate at the end of the year could be materially different from the estimated annual effective income tax rate for the nine months ended September 30, 2023.

Unrecognized Tax Benefits

We file income tax returns in the U.S. federal jurisdiction, individual U.S. state jurisdictions and non-U.S. jurisdictions. With few exceptions, we are no longer subject to U.S. federal, U.S. state, or non-U.S. income tax examinations by tax authorities for years prior to 2017.

As of September 30, 2023 and December 31, 2022, unrecognized tax benefits of $1.5 million and $1.4 million, respectively, would affect the effective tax rate if recognized.

We do not anticipate material changes to the amount of unrecognized tax benefits within the next twelve months.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Basis of Presentation

9 Months Ended

Sep. 30, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

1. Basis of Presentation

The accompanying unaudited condensed consolidated financial statements and related disclosures have been prepared in accordance with accounting principles generally accepted in the United States applicable to interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments considered necessary for a fair presentation of Koppers Holdings Inc.’s and its subsidiaries’ (Koppers, Koppers Holdings, the Company, we or us) financial position and interim results as of and for the periods presented have been included. All such adjustments are of a normal recurring nature unless disclosed otherwise. Because our business is seasonal, results for interim periods are not necessarily indicative of those that may be expected for a full year. The Condensed Consolidated Balance Sheet as of December 31, 2022 has been summarized from the audited balance sheet contained in the Annual Report on Form 10-K as of and for the year ended December 31, 2022. Certain prior period amounts in the condensed consolidated financial statements and notes to the condensed consolidated financial statements have been reclassified to conform to the current period’s presentation.

The financial information included herein should be read in conjunction with our audited consolidated financial statements and related notes included in our Annual Report on Form 10-K for the year ended December 31, 2022.

Segment Information - Summary of Assets and Goodwill by Segments (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Segment Reporting Asset Reconciling Item [Line Items]
Assets	$ 1,810.2	$ 1,711.4
Goodwill	292.9	294.0
Railroad and Utility Products and Services [Member] \| Operating Segments [Member]
Segment Reporting Asset Reconciling Item [Line Items]
Assets	739.3	660.8
Goodwill	120.4	120.6
Performance Chemicals [Member] \| Operating Segments [Member]
Segment Reporting Asset Reconciling Item [Line Items]
Assets	521.5	516.9
Goodwill	172.5	173.4
Carbon Materials and Chemicals [Member] \| Operating Segments [Member]
Segment Reporting Asset Reconciling Item [Line Items]
Assets	515.0	500.5
All Other [Member] \| Operating Segments [Member]
Segment Reporting Asset Reconciling Item [Line Items]
Assets	$ 34.4	$ 33.2

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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+ Details

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References + Details

Stock-based Compensation - Additional Information (Detail) - shares	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target shares for units	1,024,920	761,644
Stock options issued	0
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based awards, vesting period	3 years
Target shares for units	525,635	524,612
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting performance stock units if minimum performance criteria are not achieved	0
Stock options, term in years	3 years
Target shares for units	499,285	237,032
Performance Stock Units [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target award earned by participants	200.00%
Performance Stock Units [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target award earned by participants	0.00%
Performance Stock Units [Member] \| Target Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target shares for units	188,238
Market Condition Units [Member] \| Target Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target shares for units	78,411

Comprehensive Income (Loss) and Equity - Schedule of Changes in Equity (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	$ 456.6	$ 379.2	$ 403.0	$ 410.8
Net income (loss)	26.2	19.0	76.8	49.4
Dividends	(1.2)	(1.0)	(4.1)	(3.2)
Issuance of common stock	1.3	0.3	3.2	0.9
Repurchases of common stock	(3.9)		(9.8)	(18.5)
Employee stock plans	5.1	3.2	13.0	10.1
Other comprehensive (loss) income
Currency translation adjustment	(10.1)	(19.9)	9.6	(40.8)
Unrealized gain (loss) on cash flow hedges	1.6	(8.7)	2.5	(37.4)
Unrecognized pension net loss	0.4	0.3	1.0	1.0
Balance	476.0	372.4	476.0	372.4
Common Stock [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	0.2	0.2	0.2	0.2
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Dividends	0.0	0.0	0.0	0.0
Issuance of common stock	0.0	0.0	0.0	0.0
Repurchases of common stock	0.0		0.0	0.0
Employee stock plans	0.0	0.0	0.0	0.0
Other comprehensive (loss) income
Currency translation adjustment	0.0	0.0	0.0	0.0
Unrealized gain (loss) on cash flow hedges	0.0	0.0	0.0	0.0
Unrecognized pension net loss	0.0	0.0	0.0	0.0
Balance	0.2	0.2	0.2	0.2
Additional Paid-In Capital [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	273.7	257.0	263.9	249.5
Net income (loss)	0.0	0.0	0.0	0.0
Dividends	0.0	0.0	0.0	0.0
Issuance of common stock	1.3	0.3	3.2	0.9
Repurchases of common stock	0.0		0.0	0.0
Employee stock plans	5.1	3.2	13.0	10.1
Other comprehensive (loss) income
Currency translation adjustment	0.0	0.0	0.0	0.0
Unrealized gain (loss) on cash flow hedges	0.0	0.0	0.0	0.0
Unrecognized pension net loss	0.0	0.0	0.0	0.0
Balance	280.1	260.5	280.1	260.5
Retained Earnings [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	407.3	329.3	360.2	300.9
Net income (loss)	26.3	19.1	76.3	49.6
Dividends	(1.2)	(1.0)	(4.1)	(3.2)
Issuance of common stock	0.0	0.0	0.0	0.0
Repurchases of common stock	0.0		0.0	0.0
Employee stock plans	0.0	0.0	0.0	0.0
Other comprehensive (loss) income
Currency translation adjustment	0.0	0.0	0.0	0.0
Unrealized gain (loss) on cash flow hedges	0.0	0.0	0.0	0.0
Unrecognized pension net loss	0.0	0.0	0.0	0.0
Balance	432.4	347.4	432.4	347.4
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(95.1)	(88.7)	(97.3)	(40.0)
Net income (loss)	0.0	0.0	0.0	0.0
Dividends	0.0	0.0	0.0	0.0
Issuance of common stock	0.0	0.0	0.0	0.0
Repurchases of common stock	0.0		0.0	0.0
Employee stock plans	0.0	0.0	0.0	0.0
Other comprehensive (loss) income
Currency translation adjustment	(10.2)	19.6	(9.5)	(40.2)
Unrealized gain (loss) on cash flow hedges	1.6	(8.7)	2.5	(37.4)
Unrecognized pension net loss	0.4	0.3	1.0	1.0
Balance	(103.3)	(116.7)	(103.3)	(116.7)
Treasury Stock [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	(133.5)	(122.5)	(127.6)	(104.0)
Net income (loss)	0.0	0.0	0.0	0.0
Dividends	0.0	0.0	0.0	0.0
Issuance of common stock	0.0	0.0	0.0	0.0
Repurchases of common stock	(3.9)		(9.8)	(18.5)
Employee stock plans	0.0	0.0	0.0	0.0
Other comprehensive (loss) income
Currency translation adjustment	0.0	0.0	0.0	0.0
Unrealized gain (loss) on cash flow hedges	0.0	0.0	0.0	0.0
Unrecognized pension net loss	0.0	0.0	0.0	0.0
Balance	(137.4)	(122.5)	(137.4)	(122.5)
Noncontrolling Interests [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance	4.0	3.9	3.6	4.2
Net income (loss)	(0.1)	(0.1)	0.5	(0.2)
Dividends	0.0	0.0	0.0	0.0
Issuance of common stock	0.0	0.0	0.0	0.0
Repurchases of common stock	0.0		0.0	0.0
Employee stock plans	0.0	0.0	0.0	0.0
Other comprehensive (loss) income
Currency translation adjustment	0.1	(0.3)	(0.1)	(0.6)
Unrealized gain (loss) on cash flow hedges	0.0	0.0	0.0	0.0
Unrecognized pension net loss	0.0	0.0	0.0	0.0
Balance	$ 4.0	$ 3.5	$ 4.0	$ 3.5

Segment Information - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($) Segment	Dec. 31, 2022 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| Segment	3
Contract with customer, asset, net, current \| $	$ 7.8	$ 8.3

Segment Information - Schedule of Segment Revenues for Significant Product Lines (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Net sales	$ 550.4	$ 536.1	$ 1,641.0	$ 1,497.9
Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Net sales	32.7	26.7	87.7	74.1
Railroad and Utility Products and Services [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	234.0	207.7	681.5	595.3
Railroad and Utility Products and Services [Member] \| Railroad Treated Products [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	142.7	120.6	408.7	348.2
Railroad and Utility Products and Services [Member] \| Utility Poles [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	68.9	63.0	203.4	178.7
Railroad and Utility Products and Services [Member] \| Railroad Infrastructure Services [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	16.0	16.3	49.8	46.8
Railroad and Utility Products and Services [Member] \| Rail Joints [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	6.4	7.8	19.6	21.6
Performance Chemicals [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	179.4	153.1	507.2	439.1
Performance Chemicals [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Net sales	8.4	6.8	21.2	16.7
Performance Chemicals [Member] \| Wood Preservative Products [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	166.9	148.3	470.4	419.2
Performance Chemicals [Member] \| Other Products [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	12.5	4.8	36.8	19.9
Carbon Materials and Chemicals [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	137.0	175.3	452.3	463.5
Carbon Materials and Chemicals [Member] \| Intersegment Revenues [Member]
Segment Reporting Information [Line Items]
Net sales	24.3	19.9	66.5	57.4
Carbon Materials and Chemicals [Member] \| Other Products [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	8.7	7.8	24.8	25.5
Carbon Materials and Chemicals [Member] \| Pitch and Related Products [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	83.9	109.6	288.6	270.0
Carbon Materials and Chemicals [Member] \| Phthalic Anhydride and Other Chemicals [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	19.1	31.6	59.8	85.0
Carbon Materials and Chemicals [Member] \| Carbon Black Feedstock and Distillates [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	18.3	17.2	56.8	56.9
Carbon Materials and Chemicals [Member] \| Naphthalene [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	$ 7.0	$ 9.1	$ 22.3	$ 26.1

Condensed Consolidated Statement of Operations and Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Net sales	$ 550.4	$ 536.1	$ 1,641.0	$ 1,497.9
Cost of sales	439.0	439.7	1,313.0	1,229.4
Depreciation and amortization	14.3	16.9	42.7	44.5
(Gain) on sale of assets	0.0	0.0	(1.8)	(2.5)
Selling, general and administrative expenses	43.8	36.7	129.1	116.4
Operating profit	53.3	42.8	158.0	110.1
Other income, net	0.2	0.8	0.2	1.8
Interest expense	19.0	11.4	53.3	32.3
Income from continuing operations before income taxes	34.5	32.2	104.9	79.6
Income tax provision	8.3	13.2	28.1	29.7
Income from continuing operations	26.2	19.0	76.8	49.9
Loss on sale of discontinued operations	0.0	0.0	0.0	(0.5)
Net income	26.2	19.0	76.8	49.4
Net income (loss) attributable to noncontrolling interests	(0.1)	(0.1)	0.5	(0.2)
Net income attributable to Koppers	$ 26.3	$ 19.1	$ 76.3	$ 49.6
Basic -
Continuing operations	$ 1.27	$ 0.91	$ 3.66	$ 2.38
Discontinued operations	0	0	0	(0.02)
Earnings per basic common share	1.27	0.91	3.66	2.36
Diluted -
Continuing operations	1.22	0.91	3.54	2.35
Discontinued operations	0	0	0	(0.03)
Earnings per diluted common share	$ 1.22	$ 0.91	$ 3.54	$ 2.32
Comprehensive income (loss)	$ 18.1	$ (9.5)	$ 70.7	$ (27.7)
Comprehensive income (loss) attributable to noncontrolling interests	0.0	(0.4)	0.4	(0.6)
Comprehensive income (loss) attributable to Koppers	$ 18.1	$ (9.1)	$ 70.3	$ (27.1)
Weighted average shares outstanding (in thousands):
Basic	20,828	20,897	20,838	21,024
Diluted	21,659	21,085	21,546	21,345

Earnings per Common Share - Schedule of Computation of Basic and Diluted Earnings per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net income attributable to Koppers	$ 26.3	$ 19.1	$ 76.3	$ 49.6
Less: Loss on sale of discontinued operations	0.0	0.0	0.0	(0.5)
Income from continuing operations attributable to Koppers	$ 26.3	$ 19.1	$ 76.3	$ 50.1
Weighted average common shares outstanding (in thousands):
Basic	20,828	20,897	20,838	21,024
Effect of dilutive securities	831	188	708	321
Diluted	21,659	21,085	21,546	21,345
Earnings per common share – continuing operations:
Basic earnings per common share	$ 1.27	$ 0.91	$ 3.66	$ 2.38
Diluted earnings per common share	$ 1.22	$ 0.91	$ 3.54	$ 2.35
Other data:
Antidilutive securities excluded from computation of diluted earnings per common share	311	1,088	496	1,075

New Accounting Pronouncements (Policies)	9 Months Ended
New Accounting Pronouncements (Policies)	Sep. 30, 2023
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	In March 2022, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) No. 2022-01, Derivatives and Hedging (Topic 815): Fair Value Hedging—Portfolio Layer Method. This ASU amends and simplifies existing guidance in order to allow companies to more accurately present the economic effects of risk management activities in financial statements. The adoption of this ASU in the first quarter of 2023 did not have a material impact on our financial statements as we principally utilize cash flow hedges.

Derivative Financial Instruments - Schedule of Outstanding Copper Swap Contracts (Detail) - Copper Swap Contracts [Member] £ in Millions, $ in Millions	Sep. 30, 2023 GBP (£)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 GBP (£)	Dec. 31, 2022 USD ($)
Derivatives Fair Value [Line Items]
Copper Swap Contracts Units Outstanding \| £	£ 46.3		£ 27.3
Net Fair Value - Asset (Liability) \| $		$ (0.5)		$ 3.1
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member]
Derivatives Fair Value [Line Items]
Copper Swap Contracts Units Outstanding \| £	35.3		21.3
Net Fair Value - Asset (Liability) \| $		(1.0)		2.5
Contracts Where Hedge Accounting Was not Elected [Member]
Derivatives Fair Value [Line Items]
Copper Swap Contracts Units Outstanding \| £	£ 11.0		£ 6.0
Net Fair Value - Asset (Liability) \| $		$ 0.5		$ 0.6

- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References + Details

Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash provided by (used in) operating activities:
Net income	$ 76.8	$ 49.4
Adjustments to reconcile net cash used in operating activities:
Depreciation and amortization	42.7	44.5
Stock-based compensation	13.0	10.0
Change in derivative contracts	0.0	9.0
Non-cash interest expense	4.1	2.2
(Gain) on sale of assets	(2.0)	(2.6)
Insurance proceeds	(0.8)	(0.7)
Deferred income taxes	1.6	1.1
Change in other liabilities	0.6	0.4
Other - net	(1.0)	5.3
Changes in working capital:
Accounts receivable	(27.5)	(59.0)
Inventories	(16.8)	(5.8)
Accounts payable	4.3	19.5
Accrued liabilities	(10.0)	(7.5)
Other working capital	(5.5)	1.6
Net cash provided by operating activities	79.5	67.4
Cash (used in) provided by investing activities:
Capital expenditures	(91.3)	(80.0)
Insurance proceeds received	0.8	0.7
Cash provided by sale of assets	2.2	4.2
Net cash used in investing activities	(88.3)	(75.1)
Cash provided by (used in) financing activities:
Net increase in credit facility borrowings	159.9	39.9
Borrowings of long-term debt	388.0	0.0
Repayments of long-term debt	(501.0)	(2.0)
Issuances of Common Stock	3.2	0.9
Repurchases of Common Stock	(9.8)	(18.5)
Payment of debt issuance costs	(4.9)	(4.8)
Dividends paid	(3.8)	(3.2)
Net cash provided by financing activities	31.6	12.3
Effect of exchange rate changes on cash	(2.6)	(7.3)
Net increase (decrease) in cash and cash equivalents	20.2	(2.7)
Cash and cash equivalents at beginning of period	33.3	45.5
Cash and cash equivalents at end of period	53.5	42.8
Supplemental disclosure of non-cash investing and financing activities:
Right-of-use assets obtained in exchange for new operating lease liabilities	16.1	10.5
Accrued capital expenditures	$ 5.6	$ 7.6

Commitments and Contingent Liabilities

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingent Liabilities

13. Commitments and Contingent Liabilities

We are involved in litigation and various proceedings relating to environmental laws and regulations, product liability and other matters. Certain of these matters are discussed below. The ultimate resolution of these contingencies is subject to significant uncertainty and should we fail to prevail in any of these legal matters or should several of these legal matters be resolved against us in the same reporting period, these legal matters could, individually or in the aggregate, be material to the condensed consolidated financial statements.

Legal Proceedings

Coal Tar Pitch Cases. Koppers Inc. is one of several defendants in lawsuits filed in two states in which the plaintiffs claim they suffered a variety of illnesses (including cancer) as a result of exposure to coal tar pitch sold by the defendants. There were 51 plaintiffs in 27 cases pending as of September 30, 2023 and December 31, 2022. As of September 30, 2023, there were 26 cases pending in the Court of Common Pleas of Allegheny County, Pennsylvania, and one case pending in the Circuit Court of Knox County, Tennessee.

The plaintiffs in all 27 pending cases seek to recover compensatory damages. Plaintiffs in 24 of those cases also seek to recover punitive damages. The plaintiffs in the 26 cases filed in Pennsylvania seek unspecified damages in excess of the court’s minimum jurisdictional limit. The plaintiff in the Tennessee state court case seeks damages of $15.0 million. The other defendants in these lawsuits vary from case to case and include companies such as Beazer East, Inc. (Beazer East), Honeywell International Inc., Graftech International Holdings, UCAR Carbon Company, Inc., and SGL Carbon Corporation. Discovery is proceeding in these cases. No trial dates have been set in any of these cases.

We have not provided a reserve for the coal tar pitch lawsuits because, at this time, we cannot reasonably determine the probability of a loss, and the amount of loss, if any, cannot be reasonably estimated. The timing of resolution of these cases cannot be reasonably determined. Although Koppers Inc. is vigorously defending these cases, an unfavorable resolution of these matters may have a material adverse effect on our business, financial condition, cash flows and results of operations.

Environmental and Other Litigation Matters

We are subject to federal, state, local and foreign laws and regulations and potential liabilities relating to the protection of the environment and human health and safety including, among other things, the cleanup of contaminated sites, the treatment, storage and disposal of wastes, the discharge of effluent into waterways, the emission of substances into the air and various health and safety matters. We expect to incur substantial costs for ongoing compliance with such laws and regulations. We may also face governmental or third-party claims, or otherwise incur costs, relating to cleanup of, or for injuries resulting from, contamination at sites associated with past and present operations. We accrue for environmental liabilities when a determination can be made that a liability is probable and reasonably estimable.

Environmental and Other Liabilities Retained or Assumed by Others. We have agreements with former owners of certain of our operating locations under which the former owners retained, assumed and/or agreed to indemnify us against certain environmental and other liabilities. The most significant of these agreements was entered into at Koppers Inc.’s formation on December 29, 1988 (the Acquisition). Under the related asset purchase agreement between Koppers Inc. and Beazer East, subject to certain limitations, Beazer East retained the responsibility for and agreed to indemnify Koppers Inc. against certain liabilities, damages, losses and costs, including, with certain limited exceptions, liabilities under and costs to comply with environmental laws to the extent attributable to acts or omissions occurring prior to the Acquisition and liabilities related to products sold by Beazer East prior to the Acquisition (the Indemnity). Beazer Limited, the parent company of Beazer East, unconditionally guaranteed Beazer East’s performance of the Indemnity pursuant to a guarantee.

The Indemnity provides different mechanisms, subject to certain limitations, by which Beazer East is obligated to indemnify Koppers Inc. with regard to certain environmental, product and other liabilities and imposes certain conditions on Koppers Inc. before receiving such indemnification, including, in some cases, certain limitations regarding the time period as to which claims for indemnification can be brought. In July 2004, Koppers Inc. and Beazer East agreed to amend the environmental indemnification provisions of the December 29, 1988 asset purchase agreement to extend the indemnification period for pre-closing environmental liabilities, subject to the following paragraph, and agreed to share toxic tort litigation defense arising from any sites acquired from Beazer East.

Qualified expenditures under the Indemnity are not subject to a monetary limit. Qualified expenditures under the Indemnity include (i) environmental cleanup liabilities required by third parties, such as investigation, remediation and closure costs, relating to pre-December 29, 1988 (Pre-Closing) acts or omissions of Beazer East or its predecessors; (ii) environmental claims by third parties for personal injuries, property damages and natural resources damages relating to Pre-Closing acts or omissions of Beazer East or its predecessors; (iii) punitive damages for the acts or omissions of Beazer East and its predecessors without regard to the date of the alleged conduct and (iv) product liability claims for products sold by Beazer East or its predecessors without regard to the date of the alleged conduct. The indemnification period ended July 14, 2019 (the Claim Deadline) and Beazer East may now tender certain third-party claims described in sections (i) and (ii) above to Koppers Inc. However, to the extent the third-party claims described in sections (i) and (ii) above were tendered to Beazer East by the Claim Deadline, Beazer East will continue to be required to pay the costs arising from such claims under the Indemnity. Furthermore, the Claim Deadline did not change the provisions of the Indemnity with respect to indemnification for non-environmental claims, such as product liability claims, which claims may continue to be tendered by Koppers Inc. to Beazer East.

The Indemnity provides for the resolution of issues between Koppers Inc. and Beazer East by an arbitrator on an expedited basis upon the request of either party. The arbitrator could be asked, among other things, to make a determination regarding the allocation of environmental responsibilities between Koppers Inc. and Beazer East. Arbitration decisions under the Indemnity are final and binding on the parties.

Contamination has been identified at most manufacturing and other sites of our subsidiaries. One site currently owned and operated by Koppers Inc. in the United States is listed on the National Priorities List promulgated under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended (CERCLA). Currently, at the properties acquired from Beazer East (which includes the National Priorities List site and all but one of the sites permitted under the Resource Conservation and Recovery Act (RCRA)), a significant portion of all investigative, cleanup and closure activities are being conducted and paid for by Beazer East pursuant to the terms of the Indemnity. In addition, other of Koppers Inc.’s sites are or have been operated under RCRA and various other environmental permits, and remedial and closure activities are being conducted at some of these sites.

To date, the parties that retained, assumed and/or agreed to indemnify us against the liabilities referred to above, including Beazer East, have performed their obligations in all material respects. Periodically, issues have arisen between Koppers Inc. and Beazer East and/or other indemnitors that have been resolved without arbitration. Koppers Inc. and Beazer East engage in discussions from time to time that involve, among other things, the allocation of environmental costs related to certain operating and closed facilities.

If for any reason (including disputed coverage or financial incapability) one or more of such parties fail to perform their obligations and we are held liable for or otherwise required to pay all or part of such liabilities without reimbursement, the imposition of such liabilities on us could have a material adverse effect on our business, financial condition, cash flows and results of operations. Furthermore, we could be required to record a contingent liability on our balance sheet with respect to such matters, which could result in a negative impact to our business, financial condition, cash flows and results of operations.

Domestic Environmental Matters. Koppers Inc. has been named as one of the potentially responsible parties (PRPs) at the Portland Harbor CERCLA site located on the Willamette River in Oregon. Koppers Inc. operated a coal tar pitch terminal near the site. Koppers Inc. has responded to an EPA information request and has executed a PRP agreement which outlines a private process to develop an allocation of past and future costs among more than 80 parties to the site. Koppers Inc. believes it is a de minimis contributor at the site.

The EPA issued its Record of Decision (ROD) in January 2017 for the Portland Harbor CERCLA site. The selected remedy includes a combination of sediment removal, capping, enhanced and monitored natural recovery and riverbank improvements. The ROD does not determine who is responsible for remediation costs. At that time, the net present value and undiscounted costs of the selected remedy as estimated in the ROD were approximately $1.1 billion and $1.7 billion, respectively. These costs are likely to increase given recent submissions to EPA regarding remedy design and because the remedy will not be implemented for several years. Responsibility for implementing and funding that work is yet to be determined. The funding of that work amongst the PRPs is the subject of a separate private allocation process which is ongoing.

Additionally, Koppers Inc. is involved in two separate matters involving natural resource damages at the Portland Harbor site. One matter involves claims by the trustees to recover damages based upon an assessment of damages to natural resources caused by the releases of hazardous substances to the Willamette River. The assessment serves as the foundation to estimate liabilities for settlements of natural resource damages claims or litigation to recover from those who do not settle with the trustee groups. Koppers Inc. has been engaged in a process to resolve its natural resource damage liabilities for the assessment area. A second matter involves a lawsuit filed in January 2017 by the Yakama Nation in Oregon federal court. Yakama Nation seeks recovery for response costs and the costs of assessing injury to natural resources in waterways beyond the current assessment area. Following the most recent court rulings, the Yakama Nation case has been stayed pending completion of the private allocation process for the Portland Harbor CERCLA site.

In September 2009, Koppers Inc. received a general notice letter stating that it may be a PRP at the Newark Bay CERCLA site. In January 2010, Koppers Inc. submitted a response to the general notice letter asserting that Koppers Inc. is a de minimis party at this site.

We have accrued the estimated costs of participating in the PRP group at the Portland Harbor and Newark Bay CERCLA sites and estimated de minimis contributor settlement amounts at the sites totaling $4.0 million as of September 30, 2023. The actual cost could be materially higher as there has not been a determination of how those costs will be allocated among the PRPs at the sites. Accordingly, an unfavorable resolution of these matters may have a material adverse effect on our business, financial condition, cash flows and results of operations.

There are two plant sites related to the Performance Chemicals business and one plant site related to the Utility and Industrial Products business in the United States where we have recorded environmental remediation liabilities for soil and groundwater contamination which occurred prior to our acquisition of the businesses. As of September 30, 2023, our estimated environmental remediation liability for these acquired sites totals $3.8 million.

Foreign Environmental Matters. There is one plant site related to the Performance Chemicals business located in Australia where we have recorded an environmental remediation liability for soil and groundwater contamination which occurred prior to the acquisition of the business. As of September 30, 2023, our estimated environmental remediation liability for the acquired site totals $1.2 million.

Environmental Reserves Rollforward. The following table reflects changes in the accrual for environmental remediation. A total of $2.4 million and $2.5 million are classified as current liabilities as of September 30, 2023 and December 31, 2022, respectively.


	Period ended
	September 30, 2023			December 31, 2022
(Dollars in millions)
Balance at beginning of period	$	10.9		$	10.7
Expense		0.1			1.6
Cash expenditures		(0.3	)		(1.1	)
Currency translation		(0.2	)		(0.3	)
Balance at end of period	$	10.5		$	10.9

Derivative Financial Instruments - Schedule of Fair Value of Outstanding Derivative Contracts Recorded in Balance Sheet (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Net asset (liability) on balance sheet	$ 6.5	$ 3.1
Accumulated other comprehensive gain (loss), net of tax	4.5	1.8
Copper Swap Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	(0.5)	3.1
Accumulated other comprehensive gain (loss), net of tax	(0.7)	1.8
Forward Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	0.1	0.0
Accumulated other comprehensive gain (loss), net of tax	0.0	0.0
Interest Rate Swaps [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	6.9	0.0
Accumulated other comprehensive gain (loss), net of tax	5.2	0.0
Derivative Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	4.7	3.1
Derivative Contracts [Member] \| Copper Swap Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	0.3	3.0
Derivative Contracts [Member] \| Forward Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	0.2	0.1
Derivative Contracts [Member] \| Interest Rate Swaps [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	4.2	0.0
Other Assets [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	2.9	0.4
Other Assets [Member] \| Copper Swap Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	0.2	0.4
Other Assets [Member] \| Forward Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	0.0	0.0
Other Assets [Member] \| Interest Rate Swaps [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	2.7	0.0
Accrued Liabilities [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	(1.0)	(0.4)
Accrued Liabilities [Member] \| Copper Swap Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	(0.9)	(0.3)
Accrued Liabilities [Member] \| Forward Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	(0.1)	(0.1)
Accrued Liabilities [Member] \| Interest Rate Swaps [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	0.0	$ 0.0
Other Long-Term Liabilities [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	(0.1)
Other Long-Term Liabilities [Member] \| Copper Swap Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	(0.1)
Other Long-Term Liabilities [Member] \| Forward Contracts [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	0.0
Other Long-Term Liabilities [Member] \| Interest Rate Swaps [Member]
Derivative [Line Items]
Net asset (liability) on balance sheet	$ 0.0

Segment Information - Summary of Results of Segment Operations (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues from external customers:
Depreciation and amortization expense	$ 14.3	$ 16.9	$ 42.7	$ 44.5
Items excluded from the determination of segment profit:
LIFO expense	(2.8)	(6.1)	(3.3)	(12.9)
Impairment, restructuring and plant closure costs	(0.1)	(0.3)	(0.1)	(0.2)
Gain on sale of assets	0.0	0.0	1.8	2.5
Mark-to-market commodity hedging losses	0.0	(1.9)	0.0	(9.0)
Interest expense	(19.0)	(11.4)	(53.3)	(32.3)
Depreciation and amortization	(14.3)	(16.9)	(42.7)	(44.5)
Income tax provision	(8.3)	(13.2)	(28.1)	(29.7)
Discontinued operations	0.0	0.0	0.0	(0.5)
Net income	26.2	19.0	76.8	49.4
Operating Segments [Member] \| Railroad and Utility Products and Services [Member]
Revenues from external customers:
Depreciation and amortization expense	6.2	5.6	17.9	16.5
Adjusted EBITDA:
Adjusted EBITDA	25.1	15.5	63.2	40.3
Operating Segments [Member] \| Performance Chemicals [Member]
Revenues from external customers:
Depreciation and amortization expense	3.5	3.8	10.5	11.5
Adjusted EBITDA:
Adjusted EBITDA	35.2	16.7	93.8	57.9
Operating Segments [Member] \| Carbon Materials and Chemicals [Member]
Revenues from external customers:
Depreciation and amortization expense	4.6	7.5	14.3	16.5
Adjusted EBITDA:
Adjusted EBITDA	$ 10.4	$ 36.6	$ 45.5	$ 77.8

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Schedule of Company's Financial Instruments

The following table presents the estimated fair values and the related carrying amounts of our financial instruments:


	September 30, 2023				December 31, 2022
	Fair Value		Carrying Value		Fair Value		Carrying Value
(Dollars in millions)
Financial assets:
Investments and other assets	$	1.3	$	1.3	$	1.3	$	1.3
Financial liabilities:
Long-term debt	$	884.2	$	872.9	$	801.1	$	825.3

Pensions and Post-Retirement Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2023

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost for Pension Plans

The following table provides the components of net periodic benefit cost for the pension plans:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
(Dollars in millions)
Service cost	$	0.4		$	0.3		$	1.2		$	0.9
Interest cost		2.1			1.4			6.2			4.3
Expected return on plan assets		(1.7	)		(1.9	)		(5.2	)		(5.8	)
Amortization of net loss		0.5			0.4			1.6			1.3
Net periodic benefit cost	$	1.3		$	0.2		$	3.8		$	0.7
Defined contribution plan expense	$	3.2		$	2.2		$	8.0		$	7.0

Debt - Additional Information (Detail) - USD ($)			9 Months Ended
Debt - Additional Information (Detail) - USD ($)	Oct. 11, 2023	Apr. 10, 2023	Sep. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Revolving credit facility			$ 730,000,000
Long term debt			872,900,000	$ 825,300,000
Term Loan B [Member]
Debt Instrument [Line Items]
Long term debt			387,700,000	0
Senior Notes due 2025 [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Long term debt			0	$ 500,000,000
Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Letters of credit, amount outstanding			7,800,000
Interest Rate Swap [Member] \| Term Loan B [Member]
Debt Instrument [Line Items]
Derivative, notional value			$ 250,000,000
Fixed interest rate of loan portion			3.63%
Interest rate margin			0.00%
Derivative, maturity date			Apr. 30, 2027
Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Revolving credit facility			$ 800,000,000
Swingline Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility			50,000,000
Credit Facility [Member] \| Senior Secured Credit Facilities [Member]
Debt Instrument [Line Items]
Debt instrument, unused borrowing capacity			$ 350,000,000
Amendment No. 1 to Credit Facility [Member] \| Term Loan B [Member]
Debt Instrument [Line Items]
Secured term loan		$ 400,000,000
Debt instrument, payment terms		The principal balance of the Term Loan B will be repayable in quarterly installments of $1.0 million each quarter beginning with the third quarter of 2023, with the balance due at maturity on April 10, 2030.
Percentage of face value of issued debt		97.00%
Net proceeds from secured debt, before debt financing costs		$ 388,000,000
Debt instrument, basis spread on variable rate		4.00%
Debt instrument, floor interest rate		0.50%
Debt instrument, periodic principal payment amount		$ 1,000,000
Debt instrument, frequency of periodic payment		quarterly
Debt maturity date		Apr. 10, 2030
Forecast [Member] \| Amendment Number 2 To Credit Facility [Member] \| Term Loan B [Member]
Debt Instrument [Line Items]
Debt instrument, payment terms	The principal balance of the Term Loan B will be repayable in quarterly installments in an amount equal to 0.25 percent of the principal amount, commencing on January 1, 2024 and on the last business day of each March, June, September and December thereafter, with the balance due at maturity on April 10, 2030.
Debt instrument, basis spread on variable rate	3.50%
Debt instrument, floor interest rate	0.50%
Debt instrument, frequency of periodic payment	quarterly
Debt maturity date	Apr. 10, 2030
Interest rate margin reduced	0.50%
Debt instrument, percentage of principal payment	0.25%

Pensions and Post-Retirement Benefit Plans - Components of Net Periodic Benefit Cost for Pension Plans (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Postemployment Benefits [Abstract]
Service cost	$ 0.4	$ 0.3	$ 1.2	$ 0.9
Interest cost	2.1	1.4	6.2	4.3
Expected return on plan assets	(1.7)	(1.9)	(5.2)	(5.8)
Amortization of net loss	0.5	0.4	1.6	1.3
Net periodic benefit cost	1.3	0.2	3.8	0.7
Defined contribution plan expense	$ 3.2	$ 2.2	$ 8.0	$ 7.0

Debt

9 Months Ended

Sep. 30, 2023

Debt Disclosure [Abstract]

Debt

11. Debt

The following table summarizes debt:


	Weighted Average Interest Rate			Maturity	September 30, 2023		December 31, 2022
(Dollars in millions)
Credit Facility		7.58	%	2027	$	485.2	$	325.3
Term Loan B		8.34	%	2030		387.7		0.0
Senior Notes due 2025	-			-		0.0		500.0
Debt					$	872.9	$	825.3
Less short-term debt and current maturities of long-term debt						4.0		0.0
Less unamortized debt issuance costs						9.1		7.6
Long-term debt					$	859.8	$	817.7

Credit Facility

We have an $800.0 million revolving credit agreement (the Credit Facility) with a consortium of banks. The Credit Facility also provides for a $50.0 million swingline facility and provides for the ability to incur one or more uncommitted incremental revolving or term loan facilities in an aggregate amount of at least $730.0 million, subject to applicable financial covenants. The interest rate on the Credit Facility is variable and may be based on the Secured Overnight Financing Rate (SOFR), which is the applicable benchmark for current borrowings, or an alternative benchmark depending on the borrowing type.

Borrowings under the Credit Facility are secured by a first priority lien on substantially all of the assets (excluding real property and other customary assets) of Koppers Inc., Koppers Holdings Inc. and their material domestic subsidiaries. The Credit Facility contains certain covenants that limit Koppers Inc. and its restricted subsidiaries, including, without limitation, limitations on additional indebtedness, liens, dividends, investments, acquisitions, subsidiary and certain other distributions, asset sales, transactions with affiliates and modifications to material documents, including organizational documents. In addition, such covenants give rise to events of default upon the failure by Koppers Inc. and its restricted subsidiaries to meet certain financial ratios.

As of September 30, 2023, we had approximately $350 million of unused revolving credit availability after restrictions from certain letter of credit commitments and other covenants. As of September 30, 2023, $7.8 million of commitments were utilized by outstanding letters of credit.

Term Loan B

On April 10, 2023, we entered into Amendment No. 1 to the Credit Facility which added a new class of senior secured term loans under the Credit Facility in an aggregate principal amount of $400.0 million (the Term Loan B), among other modifications. The Term Loan B was issued at 97 percent of face value, resulting in $388.0 million of net proceeds, before debt financing costs. The interest rate on the Term Loan B is variable and is based on, at our option, adjusted Term SOFR Rate or adjusted Daily Simple SOFR, in each case plus 4.00 percent with a floor of 0.50 percent. The principal balance of the Term Loan B will be repayable in quarterly installments of $1.0 million each quarter beginning with the third quarter of 2023, with the balance due at maturity on April 10, 2030.

During the nine months ended September 30, 2023, we entered into interest rate swap agreements with an aggregate notional value of $250.0 million. The interest rate swaps effectively convert the variable rate component of our borrowings to a weighted average fixed rate of 3.63 percent for a portion of our variable rate debt. This weighted average fixed rate amount excludes the interest rate margin of 4.00 percent as of September 30, 2023. All swap agreements expire in April 2027.

Senior Notes due 2025

Koppers Inc.’s $500 million Senior Notes due 2025 (the 2025 Notes) were unsecured senior obligations of Koppers Inc. and were guaranteed by Koppers Holdings Inc. and certain of Koppers Inc.’s domestic subsidiaries.

On April 11, 2023, we used the proceeds from the Term Loan B, cash on hand and available borrowing capacity under our existing Credit Facility to redeem all of the outstanding 2025 Notes at face value and to pay any fees and expenses incurred in connection with the issuance of the Term Loan B and the redemption of the 2025 Notes.

Subsequent Events

On October 11, 2023, we entered into Amendment No. 2 to the Credit Facility which reduced the interest rate margins applicable to the Term Loan B by 0.50 percent to 3.50 percent with a floor of 0.50 percent, in the case of adjusted Term SOFR Rate or adjusted Daily Simple SOFR loans, among other modifications. The principal balance of the Term Loan B will be repayable in quarterly installments in an amount equal to 0.25 percent of the principal amount, commencing on January 1, 2024 and on the last business day of each March, June, September and December thereafter, with the balance due at maturity on April 10, 2030.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Paragraph 1
-Subparagraph (SX 210.4-08(c))
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Income Taxes (Tables)

9 Months Ended

Sep. 30, 2023

Income Tax Disclosure [Abstract]

Summary of Income Taxes Reconciled with Federal Statutory Rate

The estimated annual effective income tax rate differs from the U.S. federal statutory tax rate due to:


	September 30,
	2023			2022
Federal income tax rate		21.0	%		21.0	%
Foreign earnings taxed at different rates		4.8			6.8
Nondeductible expenses		1.4			1.6
State income taxes, net of federal tax benefit		1.3			0.6
Change in tax contingency reserves		0.1			0.1
GILTI inclusion, net of foreign tax credits		(0.3	)		0.1
Interest expense deduction limitation		0.0			5.9
Estimated annual effective income tax rate		28.3	%		36.1	%

Stock-based Compensation - Summary of Status and Activity of Non-Vested Stock Units (Detail)	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested, Beginning Balance	761,644
Granted	500,067
Credited from dividends	5,063
Vested	(219,479)
Forfeited	(22,375)
Non-vested, Ending Balance	1,024,920
Beginning Balance, Non-vested, Weighted Average Grant Date Fair Value per Unit \| $ / shares	$ 32.4
Granted, Weighted Average Grant Date Fair Value per Unit \| $ / shares	30.76
Credited from dividends, Weighted Average Grant Date Fair Value per Unit \| $ / shares	26.89
Vested, Weighted Average Grant Date Fair Value per Unit \| $ / shares	26.37
Forfeited, Weighted Average Grant Date Fair Value per Unit \| $ / shares	32.01
Ending Balance, Non-vested, Weighted Average Grant Date Fair Value per Unit \| $ / shares	$ 32.85
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested, Beginning Balance	524,612
Granted	232,994
Credited from dividends	3,469
Vested	(219,479)
Forfeited	(15,961)
Non-vested, Ending Balance	525,635
Performance Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested, Beginning Balance	237,032
Granted	267,073
Credited from dividends	1,594
Vested	0
Forfeited	(6,414)
Non-vested, Ending Balance	499,285

Inventories, Net (Tables)

9 Months Ended

Sep. 30, 2023

Inventory Disclosure [Abstract]

Components of Net Inventories


	September 30, 2023		December 31, 2022
(Dollars in millions)
Raw materials	$	329.2	$	318.5
Work in process		17.8		10.2
Finished goods		129.4		130.4
	$	476.4	$	459.1
Less revaluation to LIFO		106.8		103.4
Net	$	369.6	$	355.7

Income Taxes - Summary of Income Taxes Reconciled with Federal Statutory Rate (Detail)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Federal income tax rate	21.00%	21.00%
Foreign earnings taxed at different rates	4.80%	6.80%
Nondeductible expenses	1.40%	1.60%
State income taxes, net of federal tax benefit	1.30%	0.60%
Change in tax contingency reserves	0.10%	0.10%
GILTI inclusion, net of foreign tax credits	(0.30%)	0.10%
Interest expense deduction limitation	0.00%	5.90%
Estimated annual effective income tax rate	28.30%	36.10%

Comprehensive Income (Loss) and Equity - Schedule of Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Equity [Abstract]
Net income	$ 26.2	$ 19.0	$ 76.8	$ 49.4
Changes in other comprehensive income (loss):
Currency translation adjustment	(10.1)	(20.1)	(9.6)	(40.7)
Unrealized gain (loss) on cash flow hedges, net of tax (expense) benefit of $(0.6), $4.9, $(1.0) and $21.1	1.6	(8.7)	2.5	(37.4)
Unrecognized pension net loss, net of tax expense of $0.1, $0.1, $0.2 and $0.2	0.4	0.3	1.0	1.0
Comprehensive income (loss)	18.1	(9.5)	70.7	(27.7)
Comprehensive income (loss) attributable to noncontrolling interests	0.0	(0.4)	0.4	(0.6)
Comprehensive income (loss) attributable to Koppers	$ 18.1	$ (9.1)	$ 70.3	$ (27.1)

- Definition

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References + Details

- Definition

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References + Details

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
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-Section S99
-Paragraph 1
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-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
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+ Details

Leases - Schedule of Supplemental Condensed Consolidated Balance Sheet Information Related to Leases (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Operating leases:
Operating lease right-of-use assets	$ 84.3	$ 86.3
Current operating lease liabilities	22.4	20.5
Operating lease liabilities	$ 61.8	$ 66.3

Inventories, Net - Components of Net Inventories (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Inventory Disclosure [Abstract]
Raw materials	$ 329.2	$ 318.5
Work in process	17.8	10.2
Finished goods	129.4	130.4
Inventories, gross	476.4	459.1
Less revaluation to LIFO	106.8	103.4
Net	$ 369.6	$ 355.7

Stock-based Compensation - Performance Award Fair Value Assumptions (Detail) - January 2023 Grant [Member] - Performance Stock Units [Member]	9 Months Ended
	Sep. 30, 2023 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date price per share of performance award	$ 29.01
Expected volatility	66.30%
Risk-free interest rate	4.11%
Look-back period in years	3 years
Grant date fair value per share	$ 39.51

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Earnings per Common Share (Tables)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Earnings per Common Share

The following table sets forth the computation of basic and diluted earnings per common share:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
(Dollars in millions, except share and per share amounts)
Net income attributable to Koppers	$	26.3	$	19.1	$	76.3	$	49.6
Less: Loss on sale of discontinued operations		0.0		0.0		0.0		(0.5	)
Income from continuing operations attributable to Koppers	$	26.3	$	19.1	$	76.3	$	50.1
Weighted average common shares outstanding (in thousands):
Basic		20,828		20,897		20,838		21,024
Effect of dilutive securities		831		188		708		321
Diluted		21,659		21,085		21,546		21,345
Earnings per common share – continuing operations:
Basic earnings per common share	$	1.27	$	0.91	$	3.66	$	2.38
Diluted earnings per common share		1.22		0.91		3.54		2.35
Other data:
Antidilutive securities excluded from computation of diluted earnings per common share		311		1,088		496		1,075

Stock-based Compensation - Summary of Status and Activity of Stock Options (Detail) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares
Share-Based Payment Arrangement [Abstract]
Options, Outstanding at December 31, 2022 \| shares	1,122,136
Option, Exercised \| shares	(101,938)
Options, Expired \| shares	(50,031)
Options, Outstanding at September 30, 2023 \| shares	970,167
Options, Exercisable at September 30, 2023 \| shares	808,691
Weighted Average Exercise Price per Option, Outstanding at December 31, 2022 \| $ / shares	$ 27.05
Weighted Average Exercise Price per Option, Exercised \| $ / shares	21.8
Weighted Average Exercise Price per Option, Expired \| $ / shares	42.16
Weighted Average Exercise Price per Option, Outstanding at September 30, 2023 \| $ / shares	26.83
Weighted Average Exercise Price per Option, Exercisable at September 30, 2023 \| $ / shares	$ 26.55
Weighted Average Remaining Contractual Term, Outstanding at September 30, 2023	4 years 5 months 1 day
Weighted Average Remaining Contractual Term, Exercisable at September 30, 2023	3 years 9 months 21 days
Aggregate Intrinsic Value, Outstanding at September 30, 2023 \| $	$ 12.9
Aggregate Intrinsic Value, Exercisable at September 30, 2023 \| $	$ 11.1

Condensed Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$ 3.4	$ 3.5
Property, plant and equipment, accumulated depreciation	$ 461.9	$ 462.1
Senior Convertible Preferred Stock, par value	$ 0.01	$ 0.01
Senior Convertible Preferred Stock, shares authorized	10,000,000	10,000,000
Senior Convertible Preferred Stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	80,000,000	80,000,000
Common Stock, shares issued	24,889,614	24,547,000
Treasury stock, shares	4,066,548	3,783,901

Comprehensive Income (Loss) and Equity - Schedule of Changes in Equity (Parenthetical) (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Dividends Payable [Line Items]
Dividends, per share	$ 0.06	$ 0.05	$ 0.18	$ 0.15

Segment Information

9 Months Ended

Sep. 30, 2023

Segment Reporting [Abstract]

Segment Information

7. Segment Information

We have three reportable segments: Railroad and Utility Products and Services (RUPS), Performance Chemicals (PC) and Carbon Materials and Chemicals (CMC). Our reportable segments contain multiple aggregated business units since management believes the long-term financial performance of these business units is affected by similar economic conditions. The reportable segments are each managed separately because they manufacture and distribute distinct products with different production processes.

Our RUPS segment sells treated and untreated wood products, manufactured products and services primarily to the railroad and public utility markets. Railroad products and services include procuring and treating items such as crossties, switch ties and various types of lumber used for railroad bridges and crossings and the manufacture of rail joint bars. Utility products include transmission and distribution poles and pilings. The segment also operates a railroad services business that conducts engineering, design, repair and inspection services for railroad bridges, a business related to the recovery of used crossties and utility poles and a business related to the inspection of utility poles.

Our PC segment develops, manufactures, and markets wood preservation chemicals and wood treatment technologies and services to a diverse range of end-markets including infrastructure, residential and commercial construction, and agriculture.

Our CMC segment is primarily a manufacturer of creosote, carbon pitch, naphthalene, phthalic anhydride and carbon black feedstock. Creosote is used in the treatment of wood and carbon black feedstock is used in the production of carbon black. Carbon pitch is a critical raw material used in the production of aluminum and for the production of steel in electric arc furnaces. Naphthalene is used for the production of phthalic anhydride and as a surfactant in the production of concrete. Phthalic anhydride is used in the production of plasticizers, polyester resins and alkyd paints.

Our primary measure of segment profitability is adjusted earnings before interest, income taxes, depreciation, amortization and certain non-cash and/or non-recurring items that do not contribute directly to management’s evaluation of our operating results (as defined by us, adjusted EBITDA). These items include impairment, restructuring and plant closure costs, mark-to-market commodity hedging, gain or loss on sale of assets and LIFO inventory effects. This presentation is consistent with how our chief operating decision maker evaluates the results of operations and makes strategic decisions about the business. In addition, adjusted EBITDA is the primary measure used to determine the level of achievement of management’s short-term incentive goals and related payout, as well as one of the measures used to determine performance and related payouts for certain performance share units granted to management. For these reasons, we believe that adjusted EBITDA represents the most relevant measure of segment profit and loss.

Adjusted EBITDA is reconciled to net income on a consolidated basis, the most directly comparable financial measure determined and reported in accordance with U.S. GAAP. The accounting policies of the reportable segments are the same as those described in the summary of significant accounting policies. Intersegment transactions are eliminated in consolidation.

Contract Balances

The timing of revenue recognition results in both billed accounts receivable and unbilled receivables, both classified as accounts receivable, net of allowance within the condensed consolidated balance sheet. Contract assets of $7.8 million and $8.3 million are recorded within accounts receivable, net of allowance within the condensed consolidated balance sheet as of September 30, 2023 and December 31, 2022, respectively.

The following table sets forth revenues for significant product lines, net of all intersegment transactions, for our segments:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
(Dollars in millions)
Railroad and Utility Products and Services:
Railroad treated products	$	142.7	$	120.6	$	408.7	$	348.2
Utility poles		68.9		63.0		203.4		178.7
Railroad infrastructure services		16.0		16.3		49.8		46.8
Rail joints		6.4		7.8		19.6		21.6
Total Railroad and Utility Products and Services		234.0		207.7		681.5		595.3
Performance Chemicals:
Wood preservative products		166.9		148.3		470.4		419.2
Other products		12.5		4.8		36.8		19.9
Total Performance Chemicals		179.4		153.1		507.2		439.1
Carbon Materials and Chemicals:
Pitch and related products		83.9		109.6		288.6		270.0
Phthalic anhydride and other chemicals		19.1		31.6		59.8		85.0
Carbon black feedstock and distillates		18.3		17.2		56.8		56.9
Naphthalene		7.0		9.1		22.3		26.1
Other products		8.7		7.8		24.8		25.5
Total Carbon Materials and Chemicals		137.0		175.3		452.3		463.5
Total	$	550.4	$	536.1	$	1,641.0	$	1,497.9
Intersegment revenues:
Performance Chemicals	$	8.4	$	6.8	$	21.2	$	16.7
Carbon Materials and Chemicals		24.3		19.9		66.5		57.4
Total	$	32.7	$	26.7	$	87.7	$	74.1

The following table sets forth certain operating data, net of all intersegment transactions, for our segments:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
(Dollars in millions)
Depreciation and amortization expense:
Railroad and Utility Products and Services	$	6.2		$	5.6		$	17.9		$	16.5
Performance Chemicals		3.5			3.8			10.5			11.5
Carbon Materials and Chemicals		4.6			7.5			14.3			16.5
Total	$	14.3		$	16.9		$	42.7		$	44.5
Adjusted EBITDA:
Railroad and Utility Products and Services	$	25.1		$	15.5		$	63.2		$	40.3
Performance Chemicals		35.2			16.7			93.8			57.9
Carbon Materials and Chemicals		10.4			36.6			45.5			77.8
Items excluded from the determination of segment profit:
LIFO expense(1)		(2.8	)		(6.1	)		(3.3	)		(12.9	)
Impairment, restructuring and plant closure costs		(0.1	)		(0.3	)		(0.1	)		(0.2	)
Gain on sale of assets		0.0			0.0			1.8			2.5
Mark-to-market commodity hedging losses		0.0			(1.9	)		0.0			(9.0	)
Interest expense		(19.0	)		(11.4	)		(53.3	)		(32.3	)
Depreciation and amortization		(14.3	)		(16.9	)		(42.7	)		(44.5	)
Income tax provision		(8.3	)		(13.2	)		(28.1	)		(29.7	)
Discontinued operations		0.0			0.0			0.0			(0.5	)
Net income	$	26.2		$	19.0		$	76.8		$	49.4

(1)

The LIFO expense adjustment removes the entire impact of LIFO and effectively reflects the results as if we were on a FIFO inventory basis.

The following table sets forth assets and goodwill allocated to each of our segments:


	September 30, 2023		December 31, 2022
(Dollars in millions)
Segment assets:
Railroad and Utility Products and Services	$	739.3	$	660.8
Performance Chemicals		521.5		516.9
Carbon Materials and Chemicals		515.0		500.5
All other		34.4		33.2
Total	$	1,810.2	$	1,711.4
Goodwill:
Railroad and Utility Products and Services	$	120.4	$	120.6
Performance Chemicals		172.5		173.4
Total	$	292.9	$	294.0

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Subparagraph (f)
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-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-URI https://asc.fasb.org//280/tableOfContent

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-26

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-34

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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+ Details

Fair Value Measurements - Schedule of Company's Financial Instruments (Detail) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value [Member]
Financial assets:
Investments and other assets	$ 1.3	$ 1.3
Financial liabilities:
Long-term debt	884.2	801.1
Carrying Value [Member]
Financial assets:
Investments and other assets	1.3	1.3
Financial liabilities:
Long-term debt	$ 872.9	$ 825.3

Derivative Financial Instruments - Schedule of Unrealized Loss from Contract Where Hedge Accounting Was Not Elected (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Hedges [Member] \| Contracts Where Hedge Accounting Was not Elected [Member]
Derivative [Line Items]
(Loss) from contracts where hedge accounting was not elected	$ 0.0	$ (1.9)	$ 0.0	$ (9.0)

Commitments and Contingent Liabilities - Changes in Accrued Liability for Environmental Matters (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Balance at beginning of period	$ 10.9	$ 10.7
Expense	0.1	1.6
Cash expenditures	(0.3)	(1.1)
Currency translation	(0.2)	(0.3)
Balance at end of period	$ 10.5	$ 10.9

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income taxes as a percentage of pretax income	24.10%	41.00%	26.80%	37.30%
Unrecognized tax benefits	$ 1.5		$ 1.5		$ 1.4