Quarterly report pursuant to Section 13 or 15(d)

Revenue from Contracts with Customers - Narrative (Details)

v3.8.0.1
Revenue from Contracts with Customers - Narrative (Details)
$ in Thousands
 3 Months Ended
Mar. 31, 2018
USD ($)
business_line
Mar. 31, 2017
USD ($)
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 $ 109,675 $ 98,271
Capitalized contract cost, amortization 1,000  
Reimbursable revenue    
Disaggregation of Revenue [Line Items]    
Total revenues $ 14,300 $ 15,300
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