Litigation (Details) $ in Millions	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2015 Homebuilder Defendants
Commitments and Contingencies Disclosure [Abstract]
Number of other wallboard manufacturer defendants named in lawsuit | Defendants			7
Number of homebuilders asserting individual claims | Homebuilder			12
Accrual potential liability for environmental cleanup | $	$ 13	$ 17