Acquisitions and Dispositions (Discontinued Operations) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Discontinued Operations in Consolidated Statements of Operations
Total revenues									$ 3	$ 74	$ 484
Total expenses									0	0	363
Income (loss) before provision for income tax									3	74	121
Provision for income tax expense (benefit)									1	26	33
Income (loss) from operations of discontinued operations, net of income tax									2	48	88
Gain (loss) on disposal of operations, net of income tax									0	0	(64)
Income (loss) from discontinued operations, net of income tax	$ 1	$ 2	$ 2	$ (3)	$ 31	$ 0	$ 3	$ 14	$ 2	$ 48	$ 24