Summary of Significant Accounting Policies (Earnings Per Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013		Jun. 30, 2014	Jun. 30, 2013
Basic earnings per share - continuing operations:
Income (loss) from continuing operations, net of tax	$ 352	$ (106)		$ 550	$ 152
Weighted average common shares outstanding (in shares)	326,000,000	326,000,000		326,000,000	326,000,000
Basic earnings per share – continuing operations (in dollars per share)	$ 1.08	$ (0.33)		$ 1.69	$ 0.47
Diluted earnings per share - continuing operations:
Income (loss) from continuing operations, net of tax	352	(106)		550	152
Income impact of assumed conversions	1	0		1	0
Income from continuing operations available to common shareholders and assumed conversions	$ 353	$ (106)		$ 551	$ 152
Weighted average common shares outstanding (in shares)	326,000,000	326,000,000		326,000,000	326,000,000
Incremental shares from assumed conversions (in shares)	3,000,000	0	[1]	3,000,000	3,000,000
Adjusted weighted average shares - diluted (in shares)	329,000,000	326,000,000		329,000,000	329,000,000
Diluted earnings per share – continuing operations (in dollars per share)	$ 1.07	$ (0.33)		$ 1.68	$ 0.47
Stock-Based Compensation Awards
Diluted earnings per share - continuing operations:
Stock-based compensation awards excluded from the computation of diluted earnings per share (in shares)	45,951			96,341	1,587,370

[1] Due to a loss for the three months ended June 30, 2013, there were no incremental shares in the computation because such shares would be considered antidilutive.