Convertible Preferred Stock (Details) (USD $)
In Millions, except Share data, unless otherwise specified
 0 Months Ended 12 Months Ended 2 Months Ended
May 10, 2013
Apr. 23, 2013
Dec. 31, 2014
item
Mar. 31, 2014
Jun. 06, 2014
Dec. 31, 2013
Jun. 11, 2014
May 30, 2014
Feb. 14, 2014
Series B Convertible Preferred Stock                  
Convertible Preferred Stock                  
Number of shares issued     0     701,235      
Number of shares authorized     0     980,000      
Exercise price of warrants (in dollars per unit)     $ 61.42   $ 14.004        
Exercisable period for stock options following the Advisory period 5 years                
Preferred Stock conversion ratio (in shares)         4.386        
Series B Convertible Preferred Stock | Purchase Agreement                  
Convertible Preferred Stock                  
Number of shares issued 1,137 700,098              
Exercise price of warrants (in dollars per unit) 14.004 $ 14.004              
Proceeds from issuance of shares 0.1 $ 43.0              
Warrants issued for purchase of shares of common stock (in shares) 1,246 767,651              
Purchase price per share of convertible preferred stock (in dollars per share)     $ 61.42            
Dividend rate (as a percent)     8.00%            
Accrued dividend     3.9            
Number of times of original purchase price, which will be paid to the preferred stockholders     200.00%            
Number of classes of stockholder voting rights, in the aggregate, for preferred stockholders, on an as-if converted basis, together with common stockholders     1            
Series B Convertible Preferred Stock | Minimum                  
Convertible Preferred Stock                  
Percentage of outstanding shares holders vote required for conversion of all shares of preferred stock     70.00%            
Series B Convertible Preferred Stock | Minimum | Purchase Agreement                  
Convertible Preferred Stock                  
Percentage of outstanding shares holders vote required for conversion of all shares of preferred stock     70.00%            
Series B Convertible Preferred Stock | Maximum | Purchase Agreement                  
Convertible Preferred Stock                  
Amount to be raised 60.0                
Number of shares authorized 980,000                
Warrants issued for purchase of shares of common stock (in shares) 1,075,000                
Series B-2 Convertible Preferred Stock                  
Convertible Preferred Stock                  
Amount to be raised                 40.2
Number of shares issued     0     0      
Number of shares authorized     0     655,000      
Exercise price of warrants (in dollars per unit)         $ 8.00     $ 61.42  
Warrants issued for purchase of shares of common stock (in shares)               10,258  
Preferred Stock conversion ratio (in shares)         7.678        
Accrued dividend             0.7    
Series B-2 Convertible Preferred Stock | Purchase Agreement                  
Convertible Preferred Stock                  
Number of shares issued       448,060          
Exercise price of warrants (in dollars per unit)                 $ 14.004
Proceeds from issuance of shares       27.5          
Warrants issued for purchase of shares of common stock (in shares)       491,293          
Purchase price per share of convertible preferred stock (in dollars per share)     $ 61.42            
Number of times of original purchase price, which will be paid to the preferred stockholders     150.00%            
Series B-2 Convertible Preferred Stock | Maximum | Purchase Agreement                  
Convertible Preferred Stock                  
Number of shares authorized                 655,000
Warrants issued for purchase of shares of common stock (in shares)                 718,201
Series A Convertible Preferred Stock | Purchase Agreement                  
Convertible Preferred Stock                  
Number of classes of stockholder voting rights, in the aggregate, for preferred stockholders, on an as-if converted basis, together with common stockholders     1            
Series A-1 Convertible Preferred Stock                  
Convertible Preferred Stock                  
Number of shares issued     0     939,612      
Number of shares authorized     0     1,000,000      
Series A-1 Convertible Preferred Stock | Purchase Agreement                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42            
Conversion price per share (in dollars per share)     $ 16.970            
Original conversion price per share (in dollars per share)     $ 18.564            
Original preferred stock conversion ratio (in shares)     4.386            
Preferred Stock conversion ratio (in shares)     4.798            
Accrued dividend     18.1            
Members of the Company's Board of Directors that can be elected by preferred stockholders     2            
Series A-1 Convertible Preferred Stock | After payment in full of required Series B preferred dividends | Purchase Agreement                  
Convertible Preferred Stock                  
Dividend rate (as a percent)     8.00%            
Series A-1 Convertible Preferred Stock | Liquidation, dissolution, or winding-up, payments to preferred stockholders after distribution to Series B preferred stockholders | Purchase Agreement                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42            
Series A-1 Convertible Preferred Stock | Minimum | Purchase Agreement                  
Convertible Preferred Stock                  
Percentage of outstanding shares holders vote required for conversion of all shares of preferred stock     70.00%            
Series A-2 Convertible Preferred Stock                  
Convertible Preferred Stock                  
Number of shares issued     0     983,208      
Number of shares authorized     0     983,213      
Series A-2 Convertible Preferred Stock | Purchase Agreement                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42            
Conversion price per share (in dollars per share)     $ 16.970            
Original conversion price per share (in dollars per share)     $ 18.564            
Original preferred stock conversion ratio (in shares)     4.386            
Preferred Stock conversion ratio (in shares)     4.798            
Accrued dividend     21.2            
Series A-2 Convertible Preferred Stock | After payment in full of required Series B and A-1 preferred dividends | Purchase Agreement                  
Convertible Preferred Stock                  
Dividend rate (as a percent)     8.00%            
Series A-2 Convertible Preferred Stock | Liquidation, dissolution, or winding-up, payments to preferred stockholders after distribution to Series B and Series A-1 preferred stockholders | Purchase Agreement                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42            
Series A-2 Convertible Preferred Stock | Minimum | Purchase Agreement                  
Convertible Preferred Stock                  
Percentage of outstanding shares holders vote required for conversion of all shares of preferred stock     70.00%            
Series A-3 Convertible Preferred Stock                  
Convertible Preferred Stock                  
Number of shares issued     0     142,227      
Number of shares authorized     0     142,230      
Series A-3 Convertible Preferred Stock | Purchase Agreement                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42            
Conversion price per share (in dollars per share)     $ 16.970            
Original conversion price per share (in dollars per share)     $ 18.564            
Original preferred stock conversion ratio (in shares)     4.386            
Preferred Stock conversion ratio (in shares)     4.798            
Accrued dividend     $ 3.1            
Series A-3 Convertible Preferred Stock | After payment in full of required Series B, Series A-1 and A-2 preferred dividends | Purchase Agreement                  
Convertible Preferred Stock                  
Dividend rate (as a percent)     8.00%            
Series A-3 Convertible Preferred Stock | Minimum | Purchase Agreement                  
Convertible Preferred Stock                  
Percentage of outstanding shares holders vote required for conversion of all shares of preferred stock     70.00%            
Series A-4 Convertible Preferred Stock                  
Convertible Preferred Stock                  
Number of shares issued     0     3,998      
Number of shares authorized     0     4,000      
Series A-4 Convertible Preferred Stock | Purchase Agreement                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42            
Conversion price per share (in dollars per share)     $ 18.564            
Preferred Stock conversion ratio (in shares)     4.386            
Series A-4 Convertible Preferred Stock | Liquidation, dissolution, or winding-up, payments to preferred stockholders after distribution to Series B, Series B-2, Series A-1, Series A-2 , Series A-3, Series A-5 and Series A-6 preferred stockholders                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42            
Series A-5 Convertible Preferred Stock                  
Convertible Preferred Stock                  
Number of shares issued     0     6,443      
Number of shares authorized     0     7,000      
Series A-5 Convertible Preferred Stock | Purchase Agreement                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42            
Conversion price per share (in dollars per share)     $ 18.564            
Preferred Stock conversion ratio (in shares)     4.386            
Series A-6 Convertible Preferred Stock                  
Convertible Preferred Stock                  
Number of shares issued     0     496,111      
Number of shares authorized     0     800,000      
Series A-6 Convertible Preferred Stock | Purchase Agreement                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42            
Conversion price per share (in dollars per share)     $ 18.564            
Preferred Stock conversion ratio (in shares)     4.386            
Series A-6 Convertible Preferred Stock | Liquidation, dissolution, or winding-up, payments to preferred stockholders after distribution to Series B, Series B-2, Series A-1 and Series A-2 preferred stockholders                  
Convertible Preferred Stock                  
Purchase price per share of convertible preferred stock (in dollars per share)     $ 81.42