UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current Assets
Cash and cash equivalents	$ 93,402	$ 184,009
Accounts receivable, net	782,927	696,937
Expenditures billable to clients	43,583	63,065
Other current assets	73,251	61,830
Total Current Assets	993,163	1,005,841
Fixed assets, net	123,662	118,603
Right-of-use lease assets - operating leases	299,553	311,654
Goodwill	1,668,892	1,652,723
Other intangible assets, net	904,812	937,695
Other assets	34,936	29,064
Total Assets	4,025,018	4,055,580
Current Liabilities
Accounts payable	254,650	271,769
Accrued media	195,939	237,794
Accruals and other liabilities	222,699	272,533
Advance billings	316,654	361,885
Current portion of lease liabilities - operating leases	68,785	72,255
Current portion of deferred acquisition consideration	76,661	77,946
Total Current Liabilities	1,135,388	1,294,182
Long-term debt	1,381,560	1,191,601
Long-term portion of deferred acquisition consideration	119,853	144,423
Long-term lease liabilities - operating leases	327,677	342,730
Deferred tax liabilities, net	80,311	103,093
Other liabilities	73,148	57,147
Total Liabilities	3,117,937	3,133,176
Redeemable Noncontrolling Interests	49,697	43,364
Commitments and Contingencies
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common Stock, Value, Issued	368,345	382,893
Retained Earnings (Accumulated Deficit)	10,268	(6,982)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(34,451)	(5,278)
Stockholders' Equity Attributable to Parent, Total	344,299	370,753
Stockholders' Equity Attributable to Noncontrolling Interest	513,085	508,287
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Total	857,384	879,040
Liabilities and Equity, Total	4,025,018	4,055,580
Common Class A and Common Class B
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common shares	135	118
Common Class C
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common shares	$ 2	$ 2