UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Approved plan	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	Common Shares Common Class A and Common Class B	Paid-in Capital	Paid-in Capital Approved plan	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Balance (in shares) at Dec. 31, 2021					118,252,000		179,970,000
Balance at Dec. 31, 2021	$ 879,040		$ 370,753		$ 118		$ 2		$ 382,893		$ (6,982)	$ (5,278)	$ 508,287
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	33,747										33,747
Net loss			33,747
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	55,110												59,668
Net income	93,415
Other Comprehensive Income (Loss), Net of Tax	59,678		59,678									59,678
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(33,737)		25,931								(33,747)	59,678	(59,668)
Distributions to noncontrolling interests	(29,957)												(29,957)
Reduction of noncontrolling and redeemable noncontrolling interest	(4,600)		(1,000)						(1,000)				(3,600)
Noncontrolling Interest, Increase from Acquisitions	(2,667)												(2,667)
Changes in redemption value	(20,546)		(20,546)
Stockholders Equity, Increase (Decrease) Form Change In Redemption Value Of Noncontrolling Interest, Value											(20,546)
Restricted Awards Granted or Vested (in shares)					3,678,000
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited					(111,000)
Stock Issued During Period, Value, Restricted Stock Award, Gross					$ (4)				(4)
Shares acquired and cancelled (in shares)						(6,011,000)
Shares repurchased and cancelled		$ (43,643)		$ (43,643)		$ (6)				$ (43,637)
APIC, Share-Based Payment Arrangement, Option, Increase for Cost Recognition	25,475		25,475						25,475
Conversion of shares (in shares)					15,594,000		(15,594,000)
Stock Issued During Period, Value, Conversion of Units					$ (16)				(16)
Finalization of MDC acquisition accounting	(13,993)		(16,294)						(16,294)				2,301
Other, Shares					142,000
Other	3,287		(1,603)		$ (3)				(1,246)		(354)		4,890
Balance (in shares) at Sep. 30, 2022					131,544,000		164,376,000
Balance at Sep. 30, 2022	824,893		290,417		$ 135		$ 2		348,663		6,573	(64,956)	534,476
Balance (in shares) at Jun. 30, 2022					131,838,000		164,427,000
Balance at Jun. 30, 2022	857,384		344,299		$ 135		$ 2		368,345		10,268	(34,451)	513,085
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	10,609										10,609
Net loss			10,609
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	21,573												24,665
Net income	35,274
Other Comprehensive Income (Loss), Net of Tax	30,505		30,505									30,505
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(4,769)		19,896								(10,609)	30,505	(24,665)
Changes in redemption value	(14,658)		(14,658)
Stockholders Equity, Increase (Decrease) Form Change In Redemption Value Of Noncontrolling Interest, Value											(14,658)
Restricted Awards Granted or Vested (in shares)					1,689,000
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited					(3,000)
Stock Issued During Period, Value, Restricted Stock Award, Gross					$ (2)				(2)
Shares acquired and cancelled (in shares)					(2,032,000)
Shares repurchased and cancelled	(13,876)		(13,876)			$ (4)			(13,872)
Stock-based compensation	9,583		9,583						9,583
Conversion of shares (in shares)					51,000		(51,000)
Stock Issued During Period, Value, Conversion of Units					$ (1)				(1)
Finalization of MDC acquisition accounting	(13,993)		(16,294)						(16,294)				2,301
Other, Shares					1,000
Other	(4,316)		1,259		$ (1)				904		354		(5,575)
Balance (in shares) at Sep. 30, 2022					131,544,000		164,376,000
Balance at Sep. 30, 2022	824,893		290,417		$ 135		$ 2		348,663		6,573	(64,956)	534,476
Balance (in shares) at Dec. 31, 2022					131,724,000		160,909,000
Balance at Dec. 31, 2022	944,634		482,537		$ 132		$ 2		491,899		29,445	(38,941)	462,097
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Changes in redemption value	(8,711)
Balance (in shares) at Jun. 30, 2023					116,039,000		151,649,000
Balance at Jun. 30, 2023	762,190		323,891		$ 116		$ 2		309,521		27,496	(13,244)	438,299
Balance (in shares) at Dec. 31, 2022					131,724,000		160,909,000
Balance at Dec. 31, 2022	944,634		482,537		$ 132		$ 2		491,899		29,445	(38,941)	462,097
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	(3,597)
Net loss			(3,597)								(3,597)
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	6,463												(8,548)
Net income	(12,145)
Other Comprehensive Income (Loss), Net of Tax	6,153		(20,128)									(20,128)	(26,281)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	18,298		(16,531)								3,597	(20,128)	(34,829)
Distributions to noncontrolling interests	(19,164)												(19,164)
Changes in redemption value	(621)
Stockholders Equity, Increase (Decrease) Form Change In Redemption Value Of Noncontrolling Interest, Value	621		621								621
Restricted Awards Granted or Vested (in shares)					3,647,000
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited					(13,000)
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ (175)		(175)		$ (4)				171
Shares acquired and cancelled (in shares)	(6,700,000)				(31,580,000)
Shares repurchased and cancelled	$ (204,958)		(204,958)		$ (32)				(204,926)
Stock-based compensation	33,883		33,883						33,883
Change in ownership held by Class C holders	0		14,597						(14,597)				14,597
Stock Issued During Period, Value, Acquisitions	20,119		20,119		$ 3				20,116
Stock Issued During Period, Shares, Acquisitions					2,853,000
Conversion of shares (in shares)							(9,260,000)	9,260,000
Stock Issued During Period, Value, Conversion of Units								$ (9)	(9)
Other	(1,516)		(2,252)						(1,611)		(641)		736
Balance (in shares) at Sep. 30, 2023					115,891,000		151,649,000
Balance at Sep. 30, 2023	754,254		330,817		$ 116		$ 2		324,926		24,586	(18,813)	423,437
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Liability modification of certain SARS awards	1,600
Balance (in shares) at Jun. 30, 2023					116,039,000		151,649,000
Balance at Jun. 30, 2023	762,190		323,891		$ 116		$ 2		309,521		27,496	(13,244)	438,299
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss) Attributable to Parent	653
Net loss			653								653
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	1,034												(2,464)
Net income	3,117
Other Comprehensive Income (Loss), Net of Tax	13,516		5,569									5,569	(7,947)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	10,399		4,916								(653)	5,569	(5,483)
Distributions to noncontrolling interests	(8,155)												(8,155)
Stockholders Equity, Increase (Decrease) Form Change In Redemption Value Of Noncontrolling Interest, Value	3,562		3,562								3,562
Restricted Awards Granted or Vested (in shares)					670,000
Stock Issued During Period, Value, Restricted Stock Award, Gross	175		175		$ (1)				174
Shares acquired and cancelled (in shares)					(818,000)
Shares repurchased and cancelled	(4,605)		(4,605)		$ (1)				(4,604)
Stock-based compensation	17,050		17,050						17,050
Change in ownership held by Class C holders			(215)						(215)				215
Other	1,560		2,999						3,000		(1)		(1,439)
Balance (in shares) at Sep. 30, 2023					115,891,000		151,649,000
Balance at Sep. 30, 2023	754,254		$ 330,817		$ 116		$ 2		$ 324,926		$ 24,586	$ (18,813)	$ 423,437
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Liability modification of certain SARS awards	$ 3,000