XML 50 R37.htm IDEA: XBRL DOCUMENT v3.8.0.1
Revenue - Contract Assets and Liabilities (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Revenue from Contract with Customer [Abstract]    
Unbilled service fees $ 75,363 $ 54,177
Unbilled outside vendor costs, billable to clients 57,885 31,146
Advance billings 210,245 $ 148,133
Increase in advance billings 62,112  
Revenue recognized $ 72,160