Revision of Previously Issued Financial Statements Consolidated Statement of Cash Flow (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income	$ 424	$ 295	$ 267
Deferred income taxes	(80)	(2)	(1)
Increase (decrease) in payables	114	90	94
Increase (decrease) in accrued taxes	2	(1)	0
Change in long-term liabilities	33	8	(10)
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income	433	303	270
Deferred income taxes	(79)	0
Increase (decrease) in payables	109
Increase (decrease) in accrued taxes	4
Change in long-term liabilities	26	(2)	(13)
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income	(9)	(8)	(3)
Deferred income taxes	(1)	(2)
Increase (decrease) in payables	5
Increase (decrease) in accrued taxes	(2)
Change in long-term liabilities	$ 7	$ 10	$ 3