| Cover Page Document | Dec. 31, 2019 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Dec. 31, 2019 |
| Entity Registrant Name | BMC STOCK HOLDINGS, INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-36050 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, par value $0.01 per share |
| Trading Symbol | BMCH |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001574815 |
| Amendment Flag | false |
