Equity and Earnings Per Share - Schedule of Basic and Diluted Earnings Per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Net Income from continuing operations	$ 110			$ 87	$ 52	$ 184
Net (Loss) Income from discontinued operations	8			25	(322)	58
Net Income (Loss)	$ 118	$ 42	$ (430)	$ 112	$ (270)	$ 242
Average shares outstanding	249			229	245	228
Adjustment to shares outstanding
Weighted Average Shares Outstanding for Computation of Basic Earnings Per Share of Common Stock	249			229	245	228
Net effect of potentially dilutive shares				2		1
Weighted Average Shares Outstanding for Computation of Diluted Earnings Per Share of Common Stock	249			231	245	229
Earnings per share of common stock from continuing operations	$ 0.44			$ 0.38	$ 0.21	$ 0.80
(Loss) Earnings per share of common stock from discontinued operations	$ 0.04			$ 0.11	$ (1.31)	$ 0.26
Basic and diluted (loss) earnings per share	$ 0.48			$ 0.49	$ (1.10)	$ 1.06