Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Details)

v2.4.0.8
Fair Value Measurements (Details) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended 9 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended 9 Months Ended 12 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2013
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2012
Warrant Liabilities [Member]
Sep. 30, 2013
Warrant Liabilities [Member]
Dec. 31, 2012
Warrant Liabilities [Member]
Sep. 30, 2013
Warrant Liabilities [Member]
Minimum [Member]
Dec. 31, 2012
Warrant Liabilities [Member]
Minimum [Member]
Sep. 30, 2013
Warrant Liabilities [Member]
Maximum [Member]
Dec. 31, 2012
Warrant Liabilities [Member]
Maximum [Member]
Sep. 30, 2013
Recurring [Member]
Dec. 31, 2012
Recurring [Member]
Sep. 30, 2013
Recurring [Member]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Dec. 31, 2012
Recurring [Member]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Sep. 30, 2013
Recurring [Member]
Significant Other Observable Inputs (Level 2) [Member]
Dec. 31, 2012
Recurring [Member]
Significant Other Observable Inputs (Level 2) [Member]
Sep. 30, 2013
Recurring [Member]
Significant Unobservable Inputs (Level 3) [Member]
Dec. 31, 2012
Recurring [Member]
Significant Unobservable Inputs (Level 3) [Member]
Assets:                                    
Money market funds                     $ 57,756 [1] $ 37,461 [1] $ 57,756 [1] $ 37,461 [1] $ 0 [1] $ 0 [1] $ 0 [1] $ 0 [1]
U.S. treasury securities                       39,987 [2]   39,987 [2]   0 [2]   0 [2]
Foreign exchange options                     304 [3] 488 [3] 0 [3] 0 [3] 304 [3] 488 [3] 0 [3] 0 [3]
Total                     58,060 77,936 57,756 77,448 304 488 0 0
Liabilities:                                    
Contingent warrant liabilities                     39,162 15,001 0 0 0 0 39,162 15,001
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]                                    
Expected volatility (in hundredths)         40.00% 40.00%                        
Risk-free interest rate (in hundredths)             0.10% 0.30% 0.70% 0.70%                
Expected term             1 year 2 months 12 days 1 year 10 months 24 days 3 years 4 months 24 days 4 years 2 months 12 days                
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                                    
Balance, beginning of period         15,001                          
Reclassification of contingent warrant liability to equity upon exercise of warrants   1,585 337   (1,585)                          
Net increase in fair value of contingent warrant liabilities upon revaluation 11,100   25,700 9,200 25,746                          
Balance, end of period         $ 39,162 $ 15,001                        
[1] Included in cash and cash equivalents
[2] Included in short-term investments
[3] Included in other assets