Stockholders' Equity - Additional Information (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended		12 Months Ended
	Oct. 31, 2012	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Equity [Abstract]
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
Dividends declared per common share		$ 0.05	$ 0.05
Common dividends accrued		8
Stock Repurchase Program, Authorized Amount	250
Stock Repurchase Program, Period in Force	2 years
Stock Repurchased During Period Shares One		1,397,887
Stock Repurchase Program, Remaining Authorized Repurchase Amount		211
Payments to Noncontrolling Interests		$ 7