Quarterly report pursuant to Section 13 or 15(d)

Revenue from Contracts with Customers - Narrative (Details)

v3.10.0.1
Revenue from Contracts with Customers - Narrative (Details)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2018
USD ($)
Jun. 30, 2017
USD ($)
Jun. 30, 2018
USD ($)
business_line
Jun. 30, 2017
USD ($)
Revenue from Contract with Customer [Abstract]        
Number of business lines | business_line     2  
Disaggregation of Revenue [Line Items]        
Typical payment term     30 days  
Total revenues $ 118,603 $ 109,607 $ 228,278 $ 207,878
Capitalized contract cost, amortization     2,100  
Reimbursable revenue        
Disaggregation of Revenue [Line Items]        
Total revenues $ 12,800 $ 15,200 $ 27,000 $ 30,500
Minimum        
Disaggregation of Revenue [Line Items]        
Revenue, remaining performance obligation, expected timing of satisfaction, period     2 months  
Maximum        
Disaggregation of Revenue [Line Items]        
Revenue, remaining performance obligation, expected timing of satisfaction, period     60 months