| 
           Sublease Agreement (Tables) 
         | 
        3 Months Ended | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 
           Mar. 31, 2015 
         | 
      |||||||||||||||||||||
| Sublease Agreement | |||||||||||||||||||||
| Schedule of changes in liability related to sublease agreement | 
 The changes in the liability related to the sublease agreement for the three months ended March 31, 2015 were as follows (in thousands): 
 
 
 
  | 
      ||||||||||||||||||||