CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)
$ in Thousands
 9 Months Ended 12 Months Ended
Sep. 30, 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 720,936,000 635,584,000
Common stock, shares outstanding 719,425,000 633,471,000
8.5% Convertible perpetual preferred stock    
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
Preferred stock, dividend rate, percentage 8.50% 8.50%
7.0% Convertible perpetual preferred stock    
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
Preferred stock, dividend rate, percentage 7.00% 7.00%