Segment Information - Schedule of Reconciliation of Reportable Segment Depreciation and Amortization Amounts to the Consolidated Balances (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total consolidated depreciation and amortization per unaudited consolidated statements of operations	$ 228	$ 238
Amortization of initial payments for new contracts	(19)	(15)
Total consolidated depreciation and amortization per unaudited consolidated statements of cash flows	258	262
Amortization of equity method investments	(11)	(9)
Amortization of initial payments for new contracts	(19)	(15)
Operating segments and corporate
Segment Reporting Information [Line Items]
Total consolidated depreciation and amortization per unaudited consolidated statements of operations	222	228
Adjustments
Segment Reporting Information [Line Items]
Total consolidated depreciation and amortization per unaudited consolidated statements of operations	228	238
Adjustments for non wholly owned entities	17	19
Amortization of initial payments for new contracts	(19)	(15)
Amortization of equity method investments	(11)	(9)
Amortization of initial payments for new contracts	$ (19)	$ (15)