SEC Filing Details Document Details Form 8-K/A Filing Date May 2, 2024 Document Date May 2, 2024 Form Description Amendment to a previously filed 8-K Filing Group Current Reports Company Koppers Holdings, Inc. Issuer Koppers Holdings Inc. Filing Formats iXBRL View HTML Download PDF Download DOC Download XLS XBRL XBRL Viewer EX-101.SCH - XBRL TAXONOMY EXTENSION SCHEMA XML - XBRL INSTANCE DOCUMENT