CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000,000	50,000,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	1,800,000,000	1,800,000,000
Common stock, shares issued	721,256,000	635,584,000
Common stock, shares outstanding	719,288,000	633,471,000
8.5% Convertible perpetual preferred stock; 2,650 shares issued and outstanding at March 31, 2016 and December 31, 2015; aggregate liquidation preference of $265,000
Preferred stock, shares issued	2,650,000	2,650,000
Preferred stock, shares outstanding	2,650,000	2,650,000
Preferred stock, aggregate liquidation preference	$ 265,000	$ 265,000
7.0% Convertible perpetual preferred stock; 2,597 shares issued and outstanding at March 31, 2016; aggregate liquidation preference of $259,700; 2,770 shares issued and outstanding at December 31, 2015; aggregate liquidation preference of $277,000
Preferred stock, shares issued	2,597,000	2,770,000
Preferred stock, shares outstanding	2,597,000	2,770,000
Preferred stock, aggregate liquidation preference	$ 259,700	$ 277,000