SEC Filing Details Document Details Form 10-K Filing Date Feb 28, 2024 Document Date Dec 31, 2023 Form Description Annual report which provides a comprehensive overview of the company for the past year Filing Group Annual Filings 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