Commitments and Contingencies (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Operating Leases        
Rental expense $ 500 $ 500 $ 1,400 $ 1,300
Future minimum rental payments        
2015 549   549  
2016 2,140   2,140  
2017 1,960   1,960  
2018 1,042   1,042  
Total 5,691   5,691  
Purchase Commitments        
Non-cancellable purchase commitments $ 32,100   $ 32,100  
Minimum        
Operating Leases        
Extension term of leases     3 years  
Maximum        
Operating Leases        
Extension term of leases     5 years