Income Taxes (Components Of Income (Loss) Before Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Domestic	$ 917	$ 476	$ 880
Foreign	164	82	83
Income before income taxes	$ 1,081	$ 558	$ 963