UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' DEFICIT - USD ($)	Total	Approved plan	Members' capital	Stagwell Inc. Shareholders' Equity	Stagwell Inc. Shareholders' Equity Approved plan	Common Shares Common Class A & B	Common Shares Common Class A & B Approved plan	Common Shares Class C	Paid-in Capital	Paid-in Capital Approved plan	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests	Convertible Preference Shares
Beginning balance at Dec. 31, 2020			$ 358,756,000
Balance at Dec. 31, 2020	$ 398,543,000			$ 358,756,000									$ 39,787,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	12,537,000
Contribution from Limited Liability Company (LLC)	250,000		250,000	250,000
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared	(204,929,000)		(204,929,000)	(204,929,000)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(11,936,000)												(11,936,000)
Changes in redemption value of RNCI	(72,000)		(72,000)	(72,000)
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	9,679,000			9,679,000
Other											$ 0	$ 0
Ending balance at Sep. 30, 2021			0
Balance (in shares) at Sep. 30, 2021						78,984,000		179,970,000						123,849,000
Balance at Sep. 30, 2021	1,041,230,000			385,980,000		$ 77,000		$ 2,000	$ 169,537,000		(6,153,000)	12,537,000	655,250,000	$ 209,980,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to noncontrolling interests	10,987,000
Beginning balance at Dec. 31, 2020			358,756,000
Balance at Dec. 31, 2020	398,543,000			358,756,000									39,787,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Changes in redemption value	(3,834,000)
Balance (in shares) at Dec. 31, 2021						118,252,000		179,970,000
Balance at Dec. 31, 2021	879,040,000			370,753,000		$ 118,000		$ 2,000	382,893,000		(6,982,000)	(5,278,000)	508,287,000
Beginning balance at Jun. 30, 2021	350,395,000
Balance at Jun. 30, 2021	381,342,000			350,395,000									30,947,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	12,537,000
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	9,679,000			9,679,000
Ending balance at Sep. 30, 2021			$ 0
Balance (in shares) at Sep. 30, 2021						78,984,000		179,970,000						123,849,000
Balance at Sep. 30, 2021	1,041,230,000			385,980,000		$ 77,000		$ 2,000	169,537,000		(6,153,000)	12,537,000	655,250,000	$ 209,980,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Income attributable to noncontrolling interests	9,994,000
Balance (in shares) at Dec. 31, 2021						118,252,000		179,970,000
Balance at Dec. 31, 2021	879,040,000			370,753,000		$ 118,000		$ 2,000	382,893,000		(6,982,000)	(5,278,000)	508,287,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Noncontrolling Interests, Equity Statement Impact				33,747,000							33,747,000		55,110,000
Other Comprehensive Income (Loss), Net of Tax	(59,678,000)			(59,678,000)								(59,678,000)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(29,957,000)												(29,957,000)
Changes in redemption value	(20,546,000)
Reduction of noncontrolling and redeemable noncontrolling interest	(4,600,000)			(1,000,000)					(1,000,000)				(3,600,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncontrolling Interest	2,667,000												2,667,000
Changes in redemption value of RNCI	(20,546,000)			(20,546,000)							(20,546,000)
Granting of restricted awards	0					$ (4,000)			(4,000)
Granting of restricted awards (in shares)						3,678,000
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited						(111,000)
Shares repurchased and cancelled (withheld for payroll taxes)	(14,972,000)	$ (28,671,000)		(14,972,000)	$ (28,671,000)	$ (2,000)	$ (4,000)		(14,970,000)	$ (28,667,000)
Shares acquired and cancelled (in shares)						(2,005,000)	(4,006,000)
Stock-based compensation	25,475,000			25,475,000					25,475,000
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	(1,000,000)			(1,000,000)
Conversion of shares						$ 16,000			(16,000)
Conversion of shares (in shares)						15,594,000		(15,594,000)
Finalization of MDC acquisition accounting	(13,993,000)			(16,294,000)					(16,294,000)				2,301,000
Stockholders' Equity, Other Shares						142,000
Other	(1,271,000)			(1,603,000)		$ 3,000			(1,246,000)		(354,000)		332,000
Balance (in shares) at Sep. 30, 2022						131,544,000		164,376,000
Balance at Sep. 30, 2022	824,893,000			290,417,000		$ 135,000		$ 2,000	348,663,000		6,573,000	(64,956,000)	534,476,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent, Equity Statement Impact	88,857,000
Income attributable to noncontrolling interests	59,668,000
Balance (in shares) at Jun. 30, 2022						131,838,000		164,427,000
Balance at Jun. 30, 2022	857,384,000			344,299,000		$ 135,000		$ 2,000	368,345,000		10,268,000	(34,451,000)	513,085,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss), Including Noncontrolling Interests, Equity Statement Impact				10,609,000							10,609,000
Other Comprehensive Income (Loss), Net of Tax	(30,505,000)			(30,505,000)								(30,505,000)
Changes in redemption value of RNCI	(14,658,000)			(14,658,000)							(14,658,000)
Granting of restricted awards						$ (2,000)			(2,000)
Granting of restricted awards (in shares)						1,689,000
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited						(3,000)
Shares repurchased and cancelled (withheld for payroll taxes)	(46,000)	$ (13,830,000)		(46,000)	$ (13,830,000)	$ (2,000)	$ (2,000)		(44,000)	$ (13,828,000)
Shares acquired and cancelled (in shares)						(7,000)	(2,025,000)
Stock-based compensation	9,583,000			9,583,000					9,583,000
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	0			0
Conversion of shares						$ 1,000			(1,000)
Conversion of shares (in shares)						51,000		(51,000)
Finalization of MDC acquisition accounting	(13,993,000)			(16,294,000)					(16,294,000)				2,301,000
Stockholders' Equity, Other Shares						1,000
Other	1,224,000			(1,259,000)		$ 1,000			(904,000)		354,000		2,483,000
Balance (in shares) at Sep. 30, 2022						131,544,000		164,376,000
Balance at Sep. 30, 2022	824,893,000			$ 290,417,000		$ 135,000		$ 2,000	$ 348,663,000		$ 6,573,000	$ (64,956,000)	534,476,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent, Equity Statement Impact	32,182,000
Income attributable to noncontrolling interests	$ 24,665,000												$ 21,573,000