Other Financial Information (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 66	$ 46
Other	69	77
Total other current assets	135	123
Accounts Payable, Current [Abstract]
Accounts payable	377	369
Capital expenditures incurred and included in accounts payable	$ 39	$ 29