Debt and Other Obligations (Components of Interest Expense and Amortization of Deferred Financing Costs) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Debt and Other Obligations [Abstract]
Interest expense on debt obligations	$ 157	$ 139	$ 314	$ 271
Amortization of deferred financing costs and adjustments on long-term debt	5	5	11	9
Other	(4)	(2)	(7)	(4)
Total	$ 158	$ 142	$ 318	$ 276