Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 26, 2020	Jun. 28, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Entity File Number	001-36050
Entity Registrant Name	BMC Stock Holdings, Inc.
Document Period End Date	Dec. 31, 2019
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-4687975
Entity Address, Address Line One	8020 Arco Corporate Drive, Suite 400
Entity Address, City or Town	Raleigh,
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27617
City Area Code	919
Local Phone Number	431-1000
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	BMCH
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
Entity Shell Company	false
Entity Public Float			$ 1,400
Entity Common Stock, Shares Outstanding		66,809,594
Entity Central Index Key	0001574815
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Current Fiscal Year End Date	--12-31