Cover - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 22, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	000-51515
Entity Registrant Name	Core-Mark Holding Company, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-1489747
Entity Address, Address Line One	1500 Solana Boulevard, Suite 3400
Entity Address, Postal Zip Code	76262
Entity Address, City or Town	Westlake,
Entity Address, State or Province	TX
City Area Code	940
Local Phone Number	293-8600
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	CORE
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 1,104,348,744
Entity Common Stock, Shares Outstanding		45,162,600
Documents Incorporated by Reference	The information called for by Part III of this Form 10-K will be included in an amendment to this Form 10-K or incorporated by reference to the registrant’s 2021 definitive proxy statement to be filed pursuant to Regulation 14A.
Entity Central Index Key	0001318084
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false