Debt and Other Obligations (Components of Interest Expense and Amortization of Deferred Financing Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt and Other Obligations [Abstract]
Interest expense on debt obligations	$ 158	$ 152	$ 473	$ 422
Amortization of deferred financing costs and adjustments on long-term debt	5	5	16	15
Other	(3)	(3)	(11)	(7)
Total	$ 160	$ 154	$ 478	$ 430