Earnings (Loss) Per Share - Schedule of Reconciliation of Numerator and Denominator (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net earnings (loss) attributable to Mirion Technologies, Inc. shareholders	$ 28.8	$ (36.1)	$ (96.9)
Weighted average common shares outstanding — basic (in shares)	229,959	204,991	196,369
Effect of potentially dilutive securities — stock-based awards (in shares)	874	0	0
Effect of potentially dilutive securities - convertible debt (in shares)	30,321	0	0
Weighted average common shares outstanding — diluted (in shares)	261,154	204,991	196,369
Net earnings (loss) per common share attributable to Mirion Technologies, Inc. — basic (in dollars per share)	$ 0.13	$ (0.18)	$ (0.49)
Net loss per common share attributable to Mirion Technologies, Inc — diluted (in dollars per share)	$ 0.11	$ (0.18)	$ (0.49)
Share-based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Anti-dilutive employee stock-based awards, excluded (in shares)	80	2,771	639