Income Taxes (Source of Income (Loss) Before Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
(Loss) income from continuing operations before income taxes	$ (1,089)	$ 949	$ 1,590
Income from discontinued operations before income taxes	0	0	1
(Loss) income before income tax	$ (1,089)	$ 949	$ 1,591