Capital Stock - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended		2 Months Ended	12 Months Ended
	Oct. 31, 2009	Sep. 30, 2009	Oct. 31, 2009	Dec. 31, 2011	Dec. 31, 2010	Jan. 31, 2008
Class of Stock [Line Items]
Common stock conversion price of preferred shares						$ 13.19
Common stock issuance	5,000,000	34,000,000	39,000,000
Common stock price per share upon new issuance		$ 6.75
Proceeds from common stock issuance	$ 33	$ 217
Preferred dividends description				Dividends on our 4.0% Series A Convertible Preferred Stock and 4.0% Series B Convertible Preferred Stock (preferred stock) are accrued monthly and are payable in cash as approved by the Board of Directors.
Series A and Series B preferred stock dividend rate percentage				4.00%
Preferred dividends accrued				8	8
Common stock, shares authorized				450,000,000	450,000,000
Common stock, par value				$ 0.01	$ 0.01
Common stock, issued				147,965,172
Common stock, outstanding				147,319,438	144,126,032
Treasury stock, shares				645,734	379,631
Beginning On or After January 13, 2013
Class of Stock [Line Items]
Terms of conversion - closing price of common stock				$ 22.24
Terms of conversion - consecutive trading days				20 days
Minimum
Class of Stock [Line Items]
Common stock conversion price of preferred shares	$ 11.93		11.93
Maximum | January 31, 2018
Class of Stock [Line Items]
Voting power percentage				30.00%
Series A Preferred Stock
Class of Stock [Line Items]
Preferred shares issued						2,500,000
Series B Preferred stock
Class of Stock [Line Items]
Preferred shares issued						5,400,000
Series B Preferred Stock elected to convert				90,099	88,702
Common shares issued upon conversion				760,945	748,036
Total fair value of the conversions				$ 14	$ 12
Preferred Stock
Class of Stock [Line Items]
Convertible outstanding preferred shares				64,700,000
Centerbridge | Minimum
Class of Stock [Line Items]
Aggregate Series A Liquidation Preference				$ 125