Acquisitions (Details) - USD ($)
$ in Thousands
3 Months Ended
Feb. 27, 2017
Mar. 31, 2018
Mar. 31, 2017
Business Acquisition [Line Items]      
Business acquisitions holdback liability     $ 1,438
Triad Holdings, Inc.      
Business Acquisition [Line Items]      
Purchase price to acquire common stock $ 9,200    
Cash acquired in acquisition 300    
Business acquisitions holdback liability $ 1,400    
Purchase agreement, portion of purchase price held, period from acquisition date (in months) 18 months    
Triad Holdings, Inc. | Other long-term liabilities      
Business Acquisition [Line Items]      
Payments to acquire businesses modified by measurement period adjustments   $ 1,100