Other Financial Information (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 54	$ 48
Assets held for sale	4	8
Other	69	73
Total other current assets	127	129
Accounts Payable, Current [Abstract]
Accounts payable	358	398
Capital expenditures incurred and included in accounts payable	$ 32	$ 53