XML 51 R44.htm IDEA: XBRL DOCUMENT v3.23.2
Accounts receivable, unbilled revenue (contract assets) and unearned revenue or payments on account (contract liabilities) - Narrative (Details) - USD ($)
$ in Thousands
 6 Months Ended
Jun. 30, 2023
Jun. 30, 2022
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]    
Increase in unbilled services (unbilled revenue) $ 27,379  
Decrease in unearned revenue (payments on account) 65,862  
Increase in net balance (38,483)  
Revenue, remaining performance obligation $ 13,900,000 $ 13,900,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01    
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]    
Revenue, remaining performance obligation percentage 51.00%  
Revenue, remaining performance obligation, expected timing of satisfaction, period 12 months