Equity Method Investments - Summary of Equity Method Investments (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 286	$ 305
Advantage Pipeline
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	73	70
AMPCO
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	131	129
Alba Plant
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	58	80
Other
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 24	$ 26