Annual report pursuant to Section 13 and 15(d)

Preferred Redeemable Convertible Stock - Additional Information (Details)

v3.6.0.2
Preferred Redeemable Convertible Stock - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Millions
1 Months Ended 12 Months Ended
Aug. 17, 2016
Jun. 30, 2012
Jun. 30, 2009
Mar. 31, 2008
Feb. 28, 2007
Feb. 28, 2006
Jun. 30, 2005
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Class Of Stock [Line Items]                    
Outstanding convertible promissory notes and accrued interest   $ 7.1                
Common stock, offering price per share               $ 76.80    
Common Stock                    
Class Of Stock [Line Items]                    
Conversion of stock, shares issued               127,143    
Series E Preferred Redeemable Convertible Stock                    
Class Of Stock [Line Items]                    
Preferred convertible stock, shares issued           7,984,727 7,984,727      
Preferred convertible stock sold, per share           $ 1.11 $ 1.11      
Gross proceeds from sale of convertible preferred stock           $ 8.8 $ 8.8      
Conversion of preferred stock to common stock, conversion price               $ 11.11    
Series F Preferred Redeemable Convertible Stock                    
Class Of Stock [Line Items]                    
Preferred convertible stock, shares issued         4,734,374          
Preferred convertible stock sold, per share         $ 1.30          
Gross proceeds from sale of convertible preferred stock         $ 6.2          
Conversion of preferred stock to common stock, conversion price               13.00    
Series G Preferred Stock                    
Class Of Stock [Line Items]                    
Preferred convertible stock sold, per share     $ 1.30 $ 1.30            
Gross proceeds from sale of convertible preferred stock     $ 4.3 $ 4.3            
Preferred stock, shares issued upon conversion     463,856 6,216,607            
Preferred stock, conversion price per share     $ 1.30 $ 1.04            
Conversion of preferred stock to common stock, conversion price               $ 13.00    
Senior Preferred Stock                    
Class Of Stock [Line Items]                    
Dividend rate, percentage               8.00%    
Preferred convertible stock, shares outstanding               4,875,000    
Senior Preferred Stock | Minimum                    
Class Of Stock [Line Items]                    
Preferred stock ownership percentage               50.00%    
Firm Commitment | Common Stock | Minimum                    
Class Of Stock [Line Items]                    
Aggregate proceeds from issuance of private placement               $ 15.0    
Common stock, offering price per share               $ 76.80    
Preferred Redeemable Convertible Stock                    
Class Of Stock [Line Items]                    
Preferred convertible stock, shares outstanding                 23,271,702 23,055,356
Conversion of stock, shares issued               (23,271,702)    
Preferred Redeemable Convertible Stock | IPO                    
Class Of Stock [Line Items]                    
Conversion of stock, shares converted 23,271,702                  
Conversion of stock, shares issued 2,327,122                  
Preferred stock dividends converted into common stock 1,451,631