Noncurrent Other Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Other Liabilities, Noncurrent [Abstract]
Asset retirement obligations	$ 12	$ 13
Deferred proceeds	42	44
Deferred revenue (Note 21)	6	7
Derivatives (Note 17)	58	11
Environmental (Note 12)	52	49
Insurance	42	37
Other	28	47
Total	$ 240	$ 208