Equity Method Investments - Translation Gains or Losses (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Equity Method Investments [Line Items]
Translation (loss) gain	$ (38)	$ 8	$ (26)	$ 48
USG Boral Building Products
Schedule of Equity Method Investments [Line Items]
Translation (loss) gain	$ (24)	$ (1)	$ (21)	$ 23

Amount after tax, before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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