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			6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Statement [Abstract]
Net (Loss) Income from continuing operations	$ 38		$ 53	$ (392)	$ 113
Net Income from discontinued operations	4		9	4	17
Net (Loss) Income	$ 42	$ (430)	$ 62	$ (388)	$ 130
Average shares outstanding	249		228	243	228
Adjustment to shares outstanding
Weighted Average Shares Outstanding for Computation of Basic Earnings Per Share of Common Stock	249		228	243	228
Net effect of potentially dilutive shares (a)			1		1
Weighted Average Shares Outstanding for Computation of Diluted Earnings Per Share of Common Stock	249		229	243	229
Earnings (Loss) per share of common stock from Continuing Operations - Basic and Diluted	$ 0.16		$ 0.23	$ (1.61)	$ 0.50
Earnings per share of common stock from discontinued operations	$ 0.01		$ 0.04	$ 0.01	$ 0.07
Basic and diluted (loss) earnings per share	$ 0.17		$ 0.27	$ (1.60)	$ 0.57