Quarterly report pursuant to Section 13 or 15(d)

Common Stock, Stock Options and Warrants - Narrative (Details)

v3.5.0.2
Common Stock, Stock Options and Warrants - Narrative (Details) - USD ($)
 1 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended
Aug. 31, 2015
Dec. 31, 2013
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Stock repurchase program, authorized amount     $ 50,000,000.0   $ 50,000,000.0      
Stock repurchased during period (in shares)     600,000          
Stock repurchased during period     $ 5,200,000          
Stock repurchase program, remaining authorized amount     44,800,000   44,800,000      
Number of warrants authorized for repurchase               $ 25,000,000.0
Number of additional warrants authorized for repurchase $ 20,000,000.0              
Amount of available for warrants         16,700,000   $ 16,700,000  
Number of shares authorized (in shares)   11,000,000            
Income recorded as a result of remeasurement     10,926,000 $ 14,789,000 16,791,000 $ 15,743,000    
Derivative Liability                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Income recorded as a result of remeasurement     $ 10,900,000 $ 14,800,000 $ 16,800,000 $ 15,700,000    
Restricted stock units                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Employee stock option term   4 years            
Warrants outstanding     855,000   855,000   408,000  
Restricted stock units | Board member                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Employee stock options vesting term         13 months   13 months  
Public SPAC Warrants                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Warrants outstanding     6,173,000   6,173,000      
Closing stock price for 20 or 30 days to trigger call of warrants (usd per share)         $ 17.50      
Class of warrant or right, threshold days         20 days      
Number of consecutive days         30 days      
Redemption by issuer, price (usd per share)     $ 0.01   $ 0.01      
Warrant redemption period         30 days      
Public warrant, exercise by holders, price (usd per share)     $ 11.50   $ 11.50      
Estimated proceeds if warrants called         $ 71,000,000      
Minimum | Equity Incentive Plan, 2013 | Employee stock options                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Employee stock options vesting term   1 year            
Employee stock option term   5 years            
Maximum | Equity Incentive Plan, 2013 | Employee stock options                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Employee stock options vesting term   4 years            
Employee stock option term   7 years