Earnings (Loss) Per Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ (53)	$ (11)	$ 58	$ 45	$ (3)	$ 24	$ 25	$ 2	$ 39	$ 48	$ (182)
Net income (loss) attributable to noncontrolling interest									1	(1)	1
Income (loss) from continuing operations attributable to USG									38	49	(183)
Income (loss) from discontinued operations	0	0	(1)	0	(1)	(1)	0	0	(1)	(2)	2
Gain on sale of discontinued operations									0	0	55
Net income (loss) attributable to USG	(53)	(12)	57	45	(3)	23	25	2	37	47	(126)
Effect of dilutive securities - RSUs, MSUs, performance shares and stock options									0	0	0
Effect of dilutive securities - 10% convertible senior notes									0	0	0
Effect of dilutive securities - Deferred compensation program for non-employee directors									0	0	0
Income (loss) available to shareholders									$ 37	$ 47	$ (126)
Average common shares									141,722,616	108,891,703	106,382,934
Dilutive RSUs, MSUs, performance shares and stock options									2,400,000	2,500,000	0
Common shares issuable upon conversion of our 10% convertible senior notes									0	0	0
Deferred shares associated with a deferred compensation program for non-employee directors									200,000	0	0
Average diluted common shares									144,296,316	111,434,543	106,382,934
Basic earnings (loss) per average common share:
Income (loss) from continuing operations	$ (0.36)	$ (0.09)	$ 0.40	$ 0.33	$ (0.02)	$ 0.23	$ 0.23	$ 0.02	$ 0.27	$ 0.45	$ (1.72)
Income (loss) from discontinued operations									$ (0.01)	$ (0.02)	$ 0.53
Net income (loss) attributable to USG									$ 0.26	$ 0.43	$ (1.19)
Diluted earnings (loss) per average common share:
Income (loss) from continuing operations	$ (0.36)	$ (0.09)	$ 0.39	$ 0.32	$ (0.02)	$ 0.22	$ 0.22	$ 0.02	$ 0.26	$ 0.44	$ (1.72)
Income (loss) from discontinued operations									$ (0.01)	$ (0.02)	$ 0.53
Net income (loss) attributable to USG									$ 0.25	$ 0.42	$ (1.19)