SEC Filing Details Document Details Form 8-K Filing Date Feb 13, 2024 Document Date Feb 13, 2024 Form Description Report of unscheduled material events or corporate event 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