Derivative Instruments - Pretax Effects of Derivative Instruments on Consolidated Statements of Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Other Comprehensive Income on Derivatives (Effective Portion)	$ (1)	$ (5)	$ 1	$ (18)
Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	(1)	(1)	(3)	(2)
Derivatives in Cash Flow Hedging Relationships \| Cash flow hedging \| Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Other Comprehensive Income on Derivatives (Effective Portion)	0	(2)	(3)	(12)
Derivatives in Cash Flow Hedging Relationships \| Cash flow hedging \| Commodity contracts \| Cost of products sold
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	(1)	(1)	(3)	(2)
Derivatives in Cash Flow Hedging Relationships \| Cash flow hedging \| Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Other Comprehensive Income on Derivatives (Effective Portion)	(1)	(3)	4	(6)
Derivatives in Cash Flow Hedging Relationships \| Cash flow hedging \| Foreign exchange contracts \| Cost of products sold
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Reclassified from AOCI into Income (Effective Portion)	$ 0	$ 0	0	0
Derivatives Not Designated as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives			0	(1)
Derivatives Not Designated as Hedging Instruments \| Commodity contracts \| Cost of products sold
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives			$ 0	$ (1)

USG CORP 10-Q