Equity - Rollforward of Common and Preferred Stock Issued to Public (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Common Stock Shares, Beginning Balance	733,249,698	707,507,982	660,322,749
Exercise of stock options	2,387,831	2,549,131	1,667,636
Issuance of restricted stock	516,556	1,250,381	15,765
Forfeiture of unvested restricted stock	(12,000)	(11,500)	(1,730)
Common stock shares issued upon exercise of warrants	88,155,671	21,953,704	45,503,562
Common Stock Shares, Ending Balance	824,297,756	733,249,698	707,507,982
Preferred Stock Issued To Public [Member]
Preferred Stock Shares, Beginning Balance		3,614,923	4,089,999
Preferred stock used to settle warrants exercised, shares		(1,192,100)	(475,076)
Repurchases and redemption of preferred stock		(2,422,823)
Preferred Stock Shares, Ending Balance			3,614,923
Common stock shares issued upon exercise of warrants	655,496	21,953,704	45,503,562