Supplemental Cash Flows Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Payments [Abstract]
Interest payments, net of capitalized interest	$ 97	$ 119	$ 144
Income tax payments	17	25	4
Increase (Decrease) in Other Receivables	6	6	(17)
Non Cash Items Excluded From Statement of Cash Flows [Abstract]
(Increase) decrease in accrued capital expenditures	33	225	(1)
Increase in asset retirement costs	$ 46	$ (4)	$ (56)