Income (Loss) Per Common Share (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares
Numerator
Net loss attributable to Stagwell Inc. common shareholders | $	$ (3,706)
Denominator
Basic weighted average number of common shares outstanding (in shares)	90,426,215
Basic (in dollars per share) | $ / shares	$ (0.04)
Diluted (in dollars per share) | $ / shares	$ (0.04)
Class C shares
Class of Stock [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	179,970,051
Stock Appreciation Rights and Restricted Awards
Class of Stock [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	9,508,668