Sentel Acquisition - Business Acquisition (Details) - USD ($)
$ in Thousands
Mar. 30, 2018
Jan. 23, 2018
Dec. 31, 2017
Business Acquisition [Line Items]      
Goodwill $ 231,236   $ 216,930
Sentel Corporation      
Business Acquisition [Line Items]      
Receivables   $ 23,180  
Deferred taxes   3,944  
Property, plant and equipment   851  
Goodwill   14,306  
Intangible assets   10,500  
Other current assets   975  
Accounts payable   (10,012)  
Other current liabilities   (5,979)  
Other non-current liabilities   (555)  
Preliminary purchase price, net of cash acquired   $ 37,210