Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation (Details)

v3.2.0.727
Stock-based Compensation (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2015
Jun. 30, 2014
Jun. 30, 2015
Jun. 30, 2014
Stock-based awards weighted average assumptions [Abstract]        
Dividend yield (in hundredths) 0.00% 0.00% 0.00% 0.00%
Expected volatility (in hundredths) 81.00% 91.00% 82.00% 93.00%
Risk free interest rate (in hundredths) 1.65% 1.68% 1.40% 1.71%
Expected term 5 years 7 months 6 days 5 years 7 months 6 days 5 years 7 months 6 days 5 years 7 months 6 days
Stock option activity [Roll Forward]        
Outstanding beginning of period (in shares)     7,702,309  
Granted (in shares)     1,636,639  
Exercised (in shares)     (104,438)  
Forfeited, expired or cancelled (in shares)     (771,854)  
Outstanding end of period (in shares) 8,462,656   8,462,656  
Vested and expected to vest at end of period (in shares) 8,118,591   8,118,591  
Exercisable at end of period (in shares) 5,172,965   5,172,965  
Stock options activity, weighted average exercise price [Roll Forward]        
Outstanding, beginning of period (in dollars per share)     $ 8.15  
Granted (in dollars per share)     3.74  
Exercised (in dollars per share)     1.54  
Forfeited, expired or cancelled (in dollars per share)     21.84  
Outstanding, end of period (in dollars per share) $ 6.13   6.13  
Vested and expected to vest, end of period (in dollars per share) 6.20   6.20  
Exercisable weighted average exercise price (in dollars per share) $ 7.15   $ 7.15  
Additional Disclosures [Abstract]        
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2     7 years 2 months 26 days  
Vested and expected to vest, weighted average remaining contractual term     7 years 1 month 28 days  
Exercisable weighted average remaining contractual term     6 years 2 months 12 days  
Outstanding, aggregate intrinsic value at end of period $ 4,107   $ 4,107  
Vested and expected to vest, aggregate intrinsic value 4,054   4,054  
Exercisable, aggregate intrinsic value 3,179   3,179  
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]        
Total stock-based compensation expense $ 2,689 $ 2,424 $ 6,354 $ 6,348
Restricted Stock Units (RSUs) [Member]        
Unvested RSU activity [Roll Forward]        
Unvested balance beginning of period (in shares)     1,953,879  
Granted (in shares)     1,586,017  
Vested (in shares)     (881,832)  
Forfeited (in shares)     139,308  
Unvested balance end of period (in shares) 2,797,372   2,797,372  
Unvested RSU activity, weighted average grant date fair value [Roll Forward]        
Unvested balance, beginning of period (in dollars per share)     $ 5.46  
Granted (in dollars per share)     3.78  
Vested (in dollars per share)     4.86  
Forfeited (in dollars per share)     4.54  
Unvested balance, end of period (in dollars per share) $ 4.65   $ 4.65  
Research and Development [Member]        
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]        
Total stock-based compensation expense $ 1,399 953 $ 3,595 3,359
Selling, General and Administrative [Member]        
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]        
Total stock-based compensation expense $ 1,290 $ 1,471 $ 2,759 $ 2,989
Long Term Incentive Plan [Member] | Stock Options [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period     4 years  
Stock option activity [Roll Forward]        
Granted (in shares)     1,636,639  
Long Term Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period     3 years  
Stock option activity [Roll Forward]        
Granted (in shares)     1,586,017  
Employee Stock Purchase Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Common stock reserved for future issuance (in shares) 300,000   300,000  
Percentage of compensation of eligible employees to purchase shares of entity common stock at discount through payroll deductions (in hundredths)     10.00%  
Percentage related to employees to purchase shares at the lower fair market value at offering period (in hundredths)     85.00%