XML 118 R108.htm IDEA: XBRL DOCUMENT v3.10.0.1
Trade Accounts Receivable, Unbilled Services (Contract Assets) and Payments on Account (Contract Liabilities) - Contract Assets and Liabilities (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Revenue from Contract with Customer [Abstract]      
Billed services (accounts receivable) $ 423,680 $ 388,431  
Trade accounts receivable and unbilled revenue 786,606 656,940  
Allowance for doubtful accounts (8,889) (8,930) $ (9,450)
Trade accounts receivable and unbilled revenue, net 777,717 648,010  
Unbilled services (unbilled revenue) 362,926 268,509  
Unearned revenue (payments on account) (274,468) (298,992)  
Net balance 88,458 $ (30,483)  
Change in unbilled receivables 94,417    
Change in unearned revenue (payments on account) 24,524    
Change in advance payments netted against unbilled contracts receivable $ 118,941    
Change in unbilled receivables, percent 35.20%    
Change in unearned revenue (payments on account), percent (8.20%)    
Change in advance payments netted against unbilled contracts receivable, percent 390.20%    
Amounts due to third parties for reimbursable expenses $ 85,600    
Credit loss expense $ 700