Revision of Previously Issued Financial Statements Cash Flow (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net Income	$ 73	$ 72
Deferred income taxes	7	3
Increase (decrease) in payables	93	57
Changes in long-term liabilities	5	(6)
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net Income	78
Deferred income taxes	8
Increase (decrease) in payables	91	56
Changes in long-term liabilities	1	(5)
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net Income	(5)
Deferred income taxes	(1)
Increase (decrease) in payables	2	1
Changes in long-term liabilities	$ 4	$ (1)