Other Financial Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid expenses	$ 70	$ 48
Assets held for sale	0	8
Other	64	73
Total other current assets	134	129
Accounts Payable, Current [Abstract]
Accounts payable	430	398
Capital expenditures incurred and included in accounts payable	$ 25	$ 53