Document And Entity Information
Feb. 13, 2020
Document And Entity Information [Abstract]  
Document Type 8-K
Document Period End Date Feb. 13, 2020
Entity Registrant Name MRC Global inc.
Entity Incorporation, State or Country Code DE
Entity File Number 001-35479
Entity Tax Identification Number 20-5956993
Entity Address, Address Line One Fulbright Tower, 1301 McKinney Street, Suite 2300
Entity Address, City or Town Houston
Entity Address, State or Province TX
Entity Address, Postal Zip Code 77010
City Area Code 877
Local Phone Number 294-7574
Written Communications false
Soliciting Material false
Pre Commencement Tender Offer false
Pre Commencement Issuer Tender Offer false
Entity Emerging Growth Company false
Title of 12(b) Security Common Stock, par value $0.01
Trading Symbol MRC
Security Exchange Name NYSE
Entity Central Index Key 0001439095
Amendment Flag false