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
 6 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2013
Jun. 30, 2014
Warrant Liabilities [Member]
Jun. 30, 2013
Warrant Liabilities [Member]
Jun. 30, 2014
Warrant Liabilities [Member]
Jun. 30, 2014
Warrant Liabilities [Member]
Minimum [Member]
Dec. 31, 2013
Warrant Liabilities [Member]
Minimum [Member]
Jun. 30, 2014
Warrant Liabilities [Member]
Maximum [Member]
Dec. 31, 2013
Warrant Liabilities [Member]
Maximum [Member]
Jun. 30, 2014
Recurring [Member]
Dec. 31, 2013
Recurring [Member]
Jun. 30, 2014
Recurring [Member]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Dec. 31, 2013
Recurring [Member]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Jun. 30, 2014
Recurring [Member]
Significant Other Observable Inputs (Level 2) [Member]
Dec. 31, 2013
Recurring [Member]
Significant Other Observable Inputs (Level 2) [Member]
Jun. 30, 2014
Recurring [Member]
Significant Unobservable Inputs (Level 3) [Member]
Dec. 31, 2013
Recurring [Member]
Significant Unobservable Inputs (Level 3) [Member]
Assets:                                
Money market funds                 $ 49,563 [1] $ 82,759 [1] $ 49,563 [1] $ 82,759 [1] $ 0 [1] $ 0 [1] $ 0 [1] $ 0 [1]
U.S. treasury securities                 9,998 19,990 9,998 19,990 0 0 0 0
Foreign exchange options                 122 361 0 0 122 361 0 0
Total                 59,683 103,110 59,561 102,749 122 361 0 0
Liabilities:                                
Contingent warrant liabilities                 39,379 69,869 0 0 0 0 39,379 69,869
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]                                
Expected volatility (in hundredths)         72.90% 66.10% 92.80% 86.60%                
Risk-free interest rate (in hundredths)         0.10% 0.10% 0.90% 0.80%                
Expected term         0 years 4 months 24 days 0 years 10 months 24 days 2 years 8 months 12 days 3 years 2 months 12 days                
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]                                
Balance, beginning of period       69,869                        
Reclassification of contingent warrant liability to equity upon exercise of warrants       (2,526)                        
Net increase in fair value of contingent warrant liabilities upon revaluation 14,600 (8,000) 1,800 (27,964)                        
Balance, end of period   $ 39,379   $ 39,379                        
[1] Included in cash and cash equivalents