Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Numerator:
Net income attributable to Somnigroup International Inc.	$ 110.9	$ 99.0	$ 215.1	$ 65.9
Denominator:
Denominator for basic earnings per common share-weighted average shares (in shares)	210.4	209.2	210.4	202.1
Effect of dilutive securities (in shares)	2.1	3.2	2.2	3.6
Denominator for diluted earnings per common share-adjusted weighted average shares (in shares)	212.5	212.4	212.6	205.7
Basic earnings per common share (in dollars per share)	$ 0.53	$ 0.47	$ 1.02	$ 0.33
Diluted earnings per common share (in dollars per share)	$ 0.52	$ 0.47	$ 1.01	$ 0.32
Shares excluded from diluted earnings per common share computation as anti-dilutive (in shares)	1.4