Income Taxes (Source of Income (Loss) Before Income Taxes) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Sources of Income (Loss) Before Income Taxes
Income from continuing operations before income taxes	$ 1,979	$ 1,221	$ 1,861
Discontinued operations before income taxes	(525)	0	(2,235)
Income (loss) before income tax	$ 1,454	$ 1,221	$ (374)