Description of Business and Summary of Significant Accounting Policies (Concentration) (Details)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2017
USD ($)
Jun. 30, 2016
USD ($)
Jun. 30, 2017
USD ($)
item
Jun. 30, 2016
USD ($)
Revenue from U.S., Canadian and all other international dealers and distributors combined        
Total revenue $ 61,409 $ 53,215 $ 111,644 $ 96,250
International revenue (excluding Canada) as a percent of total revenue 21.00% 22.00% 21.00% 21.00%
Segment Reporting        
Number of operating segments | item     1  
United States        
Revenue from U.S., Canadian and all other international dealers and distributors combined        
Total revenue $ 42,968 $ 37,461 $ 78,154 $ 68,836
Canada        
Revenue from U.S., Canadian and all other international dealers and distributors combined        
Total revenue 5,259 4,164 9,508 7,109
All other international sources        
Revenue from U.S., Canadian and all other international dealers and distributors combined        
Total revenue $ 13,182 $ 11,590 $ 23,982 $ 20,305