Segment Information (Details 1) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) reportable_segment	Mar. 31, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | reportable_segment	3
Revenues	$ 622,444	$ 642,903
Adjusted EBITDA	72,222	101,412
Depreciation, Depletion and Amortization, Nonproduction	(33,477)	(31,204)
Asset Impairment Charges	0	(557)
Stock-based compensation	(12,004)	(8,021)
Deferred Acquisition Consideration Expense (Income)	(4,088)	(1,897)
Other items, net	(6,420)	(5,073)
Operating income	16,233	54,660
Interest and Debt Expense	(18,189)	(18,729)
Foreign exchange, net	(670)	(306)
Other Nonoperating Income (Expense)	220	156
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(2,406)	35,781
Income tax expense	2,384	3,189
Income Loss From Continuing Operations Before Equity In Earnings Of Non-consolidated Affiliates	(4,790)	32,592
Income (Loss) from Equity Method Investments	(227)	1,030
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest	(5,017)	33,622
Net Income (Loss) Attributable to Noncontrolling Interest	5,460	(20,947)
Net Income (Loss) Attributable to Parent	443	12,675
Operating Segments | Integrated Agencies Network
Segment Reporting Information [Line Items]
Revenues	329,792	348,751
Adjusted EBITDA	59,385	68,888
Operating Segments | Brand Performance Network
Segment Reporting Information [Line Items]
Revenues	213,340	197,787
Adjusted EBITDA	23,421	31,248
Operating Segments | Communications Network
Segment Reporting Information [Line Items]
Revenues	66,460	93,255
Adjusted EBITDA	4,013	16,438
Operating Segments | All Other
Segment Reporting Information [Line Items]
Revenues	12,852	3,110
Adjusted EBITDA	(3,805)	(124)
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (10,792)	$ (15,038)