Goodwill and Intangible Assets (Amortization expense) (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Amortization expense        
Amortization of intangible assets $ 1,221 $ 385 $ 3,393 $ 1,113
Cost of revenue        
Amortization expense        
Amortization of intangible assets 800 365 2,266 1,049
Research and development        
Amortization expense        
Amortization of intangible assets 50 $ 20 140 $ 64
Sales and marketing        
Amortization expense        
Amortization of intangible assets $ 371   $ 987