Long-Term Debt (Schedule of Extinguishment of Debt) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Details underlying the recognition of gain or loss on extinguishment of debt [Abstract]
Principal balance outstanding prior to payoff	$ 287	[1]
Unamortized debt issuance costs and discounts prior to payoff	(1)
Amount paid to retire debt	(309)
Gain (loss) on extinguishment of debt, pre-tax	(23)
8.75% notes, due 2019 [Member]
Details underlying the recognition of gain or loss on extinguishment of debt [Abstract]
Debt Instrument Repurchase Amount	$ 287
Interest rate	8.75%

[1] During the first quarter of 2018, we repurchased $287 million of our 8.75% senior notes due 2019.