Acquisitions and Dispositions - Narrative (Details) $ / shares in Units, € in Millions, £ in Millions																	3 Months Ended					5 Months Ended	6 Months Ended	7 Months Ended	9 Months Ended	12 Months Ended
	Nov. 01, 2023 USD ($) shares	Oct. 02, 2023 USD ($) shares	Jul. 03, 2023 USD ($)	Apr. 25, 2023 USD ($)	Apr. 25, 2023 EUR (€)	Oct. 03, 2022 USD ($)	Jul. 15, 2022 USD ($)	Jul. 12, 2022 USD ($)	May 31, 2022 USD ($)	Apr. 19, 2022 USD ($)	Apr. 01, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 GBP (£)	Dec. 01, 2021 USD ($)	Oct. 01, 2021 USD ($)	Aug. 02, 2021 USD ($) $ / shares shares	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Jun. 30, 2023 USD ($)	Aug. 02, 2021 USD ($) $ / shares	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jul. 31, 2023	Oct. 03, 2022 GBP (£)	Jul. 12, 2022 GBP (£)	Dec. 31, 2021 GBP (£)
Business Acquisition [Line Items]
Goodwill												$ 1,652,723,000					$ 1,498,815,000				$ 1,566,956,000	$ 1,652,723,000				$ 1,498,815,000	$ 1,566,956,000	$ 1,652,723,000	$ 351,725,000
Revenues																	654,895,000	$ 617,573,000	$ 632,265,000	$ 622,444,000						2,527,177,000	2,687,792,000	1,469,363,000
Income attributable to noncontrolling interests																	45,073,000	2,464,000	(1,771,000)	(4,258,000)			$ (6,029,000)	$ 39,626,000	$ (3,565,000)	41,508,000	30,125,000	14,884,000
Net Income (Loss) Attributable to Parent																	1,286,000	653,000	(3,194,000)	1,389,000			(1,805,000)		(1,152,000)	134,000	19,919,000	21,036,000
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest																	$ 46,359,000	$ 3,117,000	$ (4,965,000)	$ (2,869,000)			$ (7,834,000)		$ (4,717,000)	41,642,000	50,044,000	35,920,000
Stagwell Media
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash																$ 1.80								1.80
Hello Design
Business Acquisition [Line Items]
Aggregate purchase price											$ 4,600,000
Closing cash payment											3,600,000
Deferred acquisition consideration											$ 1,000,000
BNG
Business Acquisition [Line Items]
Aggregate purchase price										$ 20,900,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life										10 years
Goodwill										$ 24,643,000
Estimated contingent consideration										$ 50,000,000
Contingent consideration payable in cash (percent)										67.00%
Contingent consideration payable in equity (percent)										33.00%
Revenues																										30,100,000	20,500,000
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest																										(1,500,000)	100,000
Business Acquisition, Pro Forma Revenue																											2,698,018,000	1,501,568,000
Business Acquisition, Pro Forma Net Income (Loss)																											49,299,000	36,864,000
BNG | Customer Relationships
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life										10 years
BNG | Trade Names
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles										$ 5,500,000
TMA Direct
Business Acquisition [Line Items]
Remaining ownership interest acquired (percent)									87.00%
Aggregate purchase price									$ 17,200,000
Deferred acquisition consideration									$ 500,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									10 years
Goodwill									$ 6,569,000
Business Acquisition, Percentage of Voting Interests Acquired, Step One									13.00%
Business Combination, Contingent Consideration Arrangements, Change in Range of Outcomes, Contingent Consideration, Liability, Value, High									$ 13,300,000
Revenues																										11,000,000	7,700,000
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest																										1,100,000	900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles									$ 13,200,000,000	12,740,000
Business Acquisition, Pro Forma Revenue																											2,691,622,000	1,481,727,000
Business Acquisition, Pro Forma Net Income (Loss)																											51,397,000	39,386,000
Business Acquisition, Percentage of Voting Interests Acquired, Step One									13.00%
Business Combination, Contingent Consideration Arrangements, Change in Range of Outcomes, Contingent Consideration, Liability, Value, High									$ 13,300,000
TMA Direct | Customer Relationships
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									10 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles									$ 1,800,000,000	$ 6,150,000
TMA Direct | Trade Names
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life									10 years	10 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles									$ 11,400,000,000
Epicenter
Business Acquisition [Line Items]
Closing cash payment						$ 9,900,000
Deferred acquisition consideration						$ 5,000,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						5 years
Goodwill						$ 4,416,000
Revenues																										4,300,000	1,000,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net						$ 11,864,000
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest																										(700,000)	(1,200,000)
Business Acquisition, Pro Forma Revenue																											2,690,969,000	1,473,183,000
Business Acquisition, Pro Forma Net Income (Loss)																											49,652,000	35,810,000
PEP Group
Business Acquisition [Line Items]
Aggregate purchase price								$ 500,000
Estimated contingent consideration | £																																£ 2.6
Apollo
Business Acquisition [Line Items]
Aggregate purchase price							$ 2,300,000
Payments to Acquire Business, First Payment							1,000,000
Payments to Acquire Business, Second Payment							$ 1,500,000
Maru Group
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						8 years
Goodwill						$ 26,033,000
Revenues																										32,100,000	8,800,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net						25,794,000																									£ 23.0
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest																										(10,800,000)	(2,100,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles						$ 14,300,000
Business Acquisition, Pro Forma Revenue																											2,717,667,000	1,512,791,000
Business Acquisition, Pro Forma Net Income (Loss)																											36,043,000	15,167,000
Maru Group | Customer Relationships
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						10 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles						$ 4,900,000
Maru Group | Trade Names
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						10 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles						$ 4,000,000
Wolfgang
Business Acquisition [Line Items]
Remaining ownership interest acquired (percent)						80.00%																									80.00%
Closing cash payment						$ 3,800,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life						5 years
Goodwill						$ 2,451,000
Revenues																										5,700,000	2,100,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net						6,160,000
Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest																										$ 700,000	(300,000)
Business Acquisition, Pro Forma Revenue																											2,696,733,000	1,474,303,000
Business Acquisition, Pro Forma Net Income (Loss)																											$ 51,398,000	36,538,000
Wolfgang | Common Class A
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable						$ 1,200,000
Shares issued by the Company (shares) | shares																					175,000
Huskies [Member]
Business Acquisition [Line Items]
Aggregate purchase price				$ 5,600,000	€ 5.2
Goodwill				2,600,000
Business Combination, Payables to Sellers				$ 1,000,000	€ 0.9
Tinsel
Business Acquisition [Line Items]
Aggregate purchase price			$ 2,500,000
Goodwill			$ 1,600,000
Left Field Labs
Business Acquisition [Line Items]
Aggregate purchase price		$ 13,200,000
Closing cash payment		9,400,000
Deferred acquisition consideration		51,000,000
Goodwill		$ 8,700,000
Left Field Labs | Common Class A
Business Acquisition [Line Items]
Shares issued by the Company (shares) | shares		825,000
Movers and Shakers LLC
Business Acquisition [Line Items]
Aggregate purchase price	$ 15,000,000
Closing cash payment	10,200,000
Deferred acquisition consideration	35,000,000
Goodwill	$ 8,200,000
Movers and Shakers LLC | Common Class A
Business Acquisition [Line Items]
Shares issued by the Company (shares) | shares	1,000,000
MDC
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable																$ 80,000,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life																13 years
Goodwill												1,299,400,000				$ (1,290,347,000)						1,299,400,000		(1,290,347,000)				1,299,400,000
Revenues																						605,400,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net																429,062,000								429,062,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles																810,900,000								810,900,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash																$ 130,197,000								$ 130,197,000
Business Acquisition, Share Price | $ / shares																$ 5.42								$ 5.42
Business Acquisition, Pro Forma Revenue																$ 2,224,343,000													2,087,025,000
Transaction expenses																												15,000,000
MDC | Customer Relationships
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles																$ 712,900,000								$ 712,900,000
MDC | Trade Names
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life																10 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles																$ 98,000,000								$ 98,000,000
MDC | Maximum | Customer Relationships
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life																15 years
MDC | Common Units | Stagwell OpCo
Business Acquisition [Line Items]
Remaining ownership interest acquired (percent)																69.55%								69.55%
MDC | Common Class C | Stagwell Media
Business Acquisition [Line Items]
Stock Issued During Period, Shares, Acquisitions | shares																180,000,000
MDC | Common Class B
Business Acquisition [Line Items]
Common Stock, Par or Stated Value Per Share | $ / shares																$ 0.001								$ 0.001
MDC | Integrated Agencies Network
Business Acquisition [Line Items]
Goodwill																$ 932,600,000								$ 932,600,000
MDC | Brand Performance Network
Business Acquisition [Line Items]
Goodwill																285,400,000								285,400,000
MDC | Communications Network
Business Acquisition [Line Items]
Goodwill																$ 72,400,000								$ 72,400,000
Goodstuff Holdings Limited
Business Acquisition [Line Items]
Closing cash payment | £													£ 21.0
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life																10 years
Goodwill												4,400,000										4,400,000						4,400,000
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net												$ 28,200,000										28,200,000						28,200,000
Business Acquisition, Pro Forma Revenue																												1,488,500,000	902,600,000
Business Acquisition, Pro Forma Net Income (Loss)																												38,700,000	$ 72,700,000
Payments for Acquire Businesses, Working Capital Payments | £													9.0
Payment for contingent consideration | £													£ 8.0
Goodstuff Holdings Limited | Customer Relationships
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life												10 years	10 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles												$ 13,600,000										13,600,000						13,600,000
Goodstuff Holdings Limited | Trade Names
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life												15 years	15 years
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles												$ 1,300,000										$ 1,300,000						$ 1,300,000
Goodstuff Holdings Limited | Maximum
Business Acquisition [Line Items]
Deferred acquisition consideration | £																																	£ 22.0
Targeted Victory
Business Acquisition [Line Items]
Remaining ownership interest acquired (percent)															26.70%
Aggregate purchase price															$ 73,900,000
Deferred acquisition consideration															$ 46,600,000
Business Acquisition, Percentage of Voting Interests Acquired, Step One															13.30%
Contingent consideration payable in equity (percent)															50.00%
Business Acquisitions, Percentage of Voting Interests Acquired, Step Two																														13.30%
Business Combination, Consideration Transferred, Redeemable Noncontrolling Interest															$ 27,300,000
Business Acquisition, Percentage of Voting Interests Acquired, Step One															13.30%
Targeted Victory | Common Class A
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Change in Range of Outcomes, Contingent Consideration, Liability, Value, High															$ 135,000,000
Business Combination, Contingent Consideration Arrangements, Change in Range of Outcomes, Contingent Consideration, Liability, Value, High															135,000,000
ConcentricLife
Business Acquisition [Line Items]
Remaining ownership interest acquired (percent)														27.00%
Aggregate purchase price														$ 8,100,000
Closing cash payment														1,600,000
Deferred acquisition consideration															$ 6,500,000
Instrument Holdings Inc.
Business Acquisition [Line Items]
Remaining ownership interest acquired (percent)												49.00%										49.00%						49.00%					49.00%
Aggregate purchase price												$ 157,100,000
Closing cash payment														$ 37,500,000
Business Combination, Consideration Transferred, Deferred Acquisition Payment												82,100,000
Instrument Holdings Inc. | Common Class A
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable												$ 37,500,000
Contingent consideration payable in equity (percent)												40.00%										40.00%						40.00%					40.00%