Segment Information - Schedule of Reconciliation of Reportable Segment Depreciation and Amortization Amounts to the Consolidated Balances (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of reportable segment depreciation and amortization amounts to the consolidated balances
Total depreciation and amortization per consolidated statements of operations	$ 949	$ 1,022	$ 1,056
Amortization of initial payments for new contracts	65	51	45
Total consolidated depreciation and amortization per consolidated statements of cash flows	1,061	1,133	1,163
Amortization of equity method investment	(47)	(60)	(62)
Amortization of initial payments for new contracts	(65)	(51)	(45)
Operating segments and corporate
Reconciliation of reportable segment depreciation and amortization amounts to the consolidated balances
Total depreciation and amortization per consolidated statements of operations	921	999	1,032
Adjustments
Reconciliation of reportable segment depreciation and amortization amounts to the consolidated balances
Total depreciation and amortization per consolidated statements of operations	949	1,022	1,056
Adjustments for non wholly owned entities	75	83	86
Amortization of initial payments for new contracts	65	51	45
Amortization of equity method investment	(47)	(60)	(62)
Amortization of initial payments for new contracts	$ (65)	$ (51)	$ (45)