Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (USD $)
In Thousands, except Share data, unless otherwise specified
Series B-2 Convertible Preferred Stock
Series B Convertible Preferred Stock
Series A-1 Convertible Preferred Stock
Series A-2 Convertible Preferred Stock
Series A-3 Convertible Preferred Stock
Series A-4 Convertible Preferred Stock
Series A-5 Convertible Preferred Stock
Series A-6 Convertible Preferred Stock
Common Stock
Additional paid-in-capital
Accumulated Other Comprehensive Income (Loss)
Accumulated Deficit
Total
Balance at Dec. 31, 2011     $ 65,675 $ 79,979 $ 10,208 $ 271 $ 525     $ 2,744 $ 5 $ (122,359) $ (119,610)
Balance (in shares) at Dec. 31, 2011     939,612 983,208 142,227 3,998 6,443   283,047        
Increase (Decrease) in Stockholders' Equity                          
Net loss                       (69,128) (69,128)
Unrealized loss from available-for-sale securities                     (5)   (5)
Stock options exercised                   279     279
Stock options exercised (in shares)                 97,281        
Accretion of dividends on preferred stock     6,282 6,735 974         (4,818)   (9,174) (13,992)
Stock-based compensation expense                   1,795     1,795
Balance at Dec. 31, 2012     71,957 86,714 11,182 271 525         (200,661) (200,661)
Balance (in shares) at Dec. 31, 2012     939,612 983,208 142,227 3,998 6,443   380,328        
Increase (Decrease) in Stockholders' Equity                          
Net loss                       (60,690) (60,690)
Stock options exercised                   13     13
Stock options exercised (in shares)                 5,336        
Issuance of preferred stock   41,514           23,168          
Issuance of preferred stock (in shares)   701,235           496,111          
Accretion of dividends on preferred stock   2,378 6,780 7,263 1,050         (1,521)   (15,950) (17,471)
Stock-based compensation expense                   1,508     1,508
Balance at Dec. 31, 2013   43,892 78,737 93,977 12,232 271 525 23,168       (277,301) (277,301)
Balance (in shares) at Dec. 31, 2013   701,235 939,612 983,208 142,227 3,998 6,443 496,111 385,664        
Increase (Decrease) in Stockholders' Equity                          
Net loss                       (62,479) (62,479)
Unrealized loss from available-for-sale securities                     (21)   (21)
Stock options exercised                   170     170
Stock options exercised (in shares)                 49,382        
Issuance of preferred stock 26,152             10,109          
Issuance of preferred stock (in shares) 448,060             186,847          
Accretion of dividends on preferred stock 685 1,515 3,084 3,246 470         (4,542)   (4,458) (9,000)
Issuance of warrants                   41     41
Exercise of warrants                 20,435        
Stock-based compensation expense                   7,070     7,070
Issuance of common stock, net                 1 103,803     103,804
Issuance of common stock (in shares)                 10,141,268        
Conversion of convertible preferred stock into common stock (26,837) (45,407) (81,821) (97,223) (12,702) (271) (525) (33,277) 2 298,061     298,063
Conversion of convertible preferred stock into common stock (in shares) (448,060) (701,235) (939,612) (983,208) (142,227) (3,998) (6,443) (682,958) 22,327,786        
Reclassification of warrant liability to additional paid-in-capital                   3,117     3,117
Balance at Dec. 31, 2014                 $ 3 $ 407,720 $ (21) $ (344,238) $ 63,464
Balance (in shares) at Dec. 31, 2014                 32,924,535