UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	$ (5,017)	$ 33,622
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Stock-based compensation	12,004	8,021
Depreciation and amortization	33,477	31,204
Impairment and other losses	0	557
Deferred income taxes	3,809	(1,350)
Adjustment to deferred acquisition consideration	4,088	1,897
Other, net	(1,550)	(2,647)
Changes in working capital:
Accounts receivable	(12,425)	(70,039)
Expenditures billable to clients	(4,173)	11,996
Other assets	(5,986)	(6,100)
Accounts payable	(51,670)	(32,386)
Accrued expenses and other liabilities	(54,684)	(5,592)
Advance billings	(2,986)	(17,760)
Net Cash Provided by (Used in) Operating Activities, Total	(85,113)	(48,577)
Cash flows from investing activities:
Capital expenditures	(3,435)	(4,760)
Acquisitions, net of cash acquired	(220)	(935)
Capitalized software	(6,735)	(1,778)
Other	(425)	(816)
Net Cash Provided by (Used in) Investing Activities, Total	(10,815)	(8,289)
Cash flows from financing activities:
Repayment of borrowings under revolving credit facility	(426,500)	(209,500)
Proceeds from borrowings under revolving credit facility	476,500	239,000
Shares acquired and cancelled	8,263	14,926
Distributions to noncontrolling interests	(10,948)	(6,464)
Payment of deferred consideration	0	(1,581)
Repurchase of Common Stock	(17,866)	0
Net Cash Provided by (Used in) Financing Activities, Total	12,923	6,529
Effect of exchange rate changes on cash and cash equivalents	945	1,481
Net decrease in cash and cash equivalents	(82,060)	(48,856)
Cash and cash equivalents at beginning of period	220,589	184,009
Cash and cash equivalents at end of period	138,529	135,153
Supplemental Cash Flow Information:
Cash income taxes paid	15,107	6,623
Cash interest paid	33,459	30,798
Non-cash investing and financing activities:
Establishment of a deferred tax asset related to the exchange	0	24,500
Establishment of Tax Receivables Agreement liability	$ 0	$ 20,846