Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Unbilled service fees	$ 116,381	$ 116,558
Unbilled outside vendor costs, billable to clients	93,077	63,065
Advance billings	337,034	361,885
Increase (Decrease) in Advance Billings	(24,851)
Contract with Customer, Liability, Revenue Recognized	345,277
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount	52,613
Unbilled service fees	116,381	$ 116,558
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Advance Billings			$ 869
BNG, Wolfgang, and Maru
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Advance Billings	7,620
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Contract Assets	$ 3,195
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percent	82.00%
Expected timing of satisfaction	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percent	16.00%
Expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percent	2.00%
Expected timing of satisfaction	1 year