Goodwill and Intangible Assets - Identifiable Intangible Assets (Details) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Intangible Assets    
Gross Amount $ 10,841 $ 10,841
Accumulated Amortization (7,140) (6,749)
Carrying Value 3,701 4,092
License Agreement    
Intangible Assets    
Gross Amount 150 150
Accumulated Amortization (116) (113)
Carrying Value 34 37
Developed Technology    
Intangible Assets    
Gross Amount 7,301 7,301
Accumulated Amortization (3,710) (3,344)
Carrying Value 3,591 3,957
Trade Name    
Intangible Assets    
Gross Amount 440 440
Accumulated Amortization (364) (342)
Carrying Value 76 98
Customer Relationships    
Intangible Assets    
Gross Amount 2,950 2,950
Accumulated Amortization $ (2,950) $ (2,950)