Debt and Other Obligations (Components of Interest Expense and Amortization of Deferred Financing Costs) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Debt and Other Obligations [Abstract]
Interest Expense, Debt, Excluding Amortization	$ 167	$ 158
Amortization of deferred financing costs and adjustments on long-term debt	5	5
Other, net of capitalized interest	(4)	(3)
Interest expense and amortization of deferred financing costs	$ 168	$ 160