Acquisitions and Dispositions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Jun. 02, 2025	Dec. 31, 2024	Dec. 19, 2024	Oct. 01, 2024	Jan. 02, 2024	Dec. 31, 2023
Business Acquisition [Line Items]
Business Combination, Bargain Purchase, Gain Recognized, Amount	$ 9,937
Goodwill	(1,595,238)		$ (1,554,146)				$ (1,498,815)
ADK Group
Business Acquisition [Line Items]
Cash and cash equivalents		$ 34,200
Accounts receivable		19,522
Other current assets		3,025
Fixed assets		1,111
Other assets		680
Right-of-use lease assets - operating leases		1,110
Accounts payable		6,989
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accrued Media		(1,526)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other		(9,957)
Advance billings	(7,400)	(7,378)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		(1,092)
Current portion of lease liabilities		(532)
Net liabilities assumed		31,609
Business Combination, Bargain Purchase, Gain Recognized, Amount	$ 9,937
Long-term portion of lease liabilities		(565)
Purchase price consideration		$ 21,672
Unicepta
Business Acquisition [Line Items]
Cash and cash equivalents				$ 2,723
Accounts receivable				9,354
Other current assets				575
Fixed assets				429
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				36,833
Other assets				140
Right-of-use lease assets - operating leases				5,911
Accounts payable				2,808
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other				(8,463)
Advance billings				(951)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other				(406)
Current portion of lease liabilities				(1,071)
Net liabilities assumed				26,366
Goodwill				(36,048)
Long-term portion of lease liabilities				(5,400)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities				(10,500)
Purchase price consideration				$ 62,414
Consulum
Business Acquisition [Line Items]
Cash and cash equivalents					$ 2,151
Accounts receivable					26,845
Other current assets					3,094
Fixed assets					2,032
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					57,200
Right-of-use lease assets - operating leases					2,173
Accounts payable					2,078
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other					(9,167)
Advance billings					(5,425)
Current portion of lease liabilities					(983)
Net liabilities assumed					66,159
Goodwill					(16,687)
Long-term portion of lease liabilities					(1,065)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities					(8,618)
Purchase price consideration					$ 82,846
Team Epiphany
Business Acquisition [Line Items]
Cash and cash equivalents						$ 1,095
Accounts receivable						8,283
Other current assets						402
Fixed assets						184
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles						4,316
Right-of-use lease assets - operating leases						2,788
Accounts payable						1,086
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other						(664)
Advance billings						(8,808)
Current portion of lease liabilities						(516)
Net liabilities assumed						8,217
Goodwill						(8,452)
Long-term portion of lease liabilities						(2,600)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current, Expenditures Billables						4,823
Purchase price consideration						$ 16,669

Stagwell Inc 10-K