Post-effective amendment to a registration statement that is not immediately effective upon filing

Goodwill and Intangible Assets - Schedule of Goodwill (Details)

v3.22.0.1
Goodwill and Intangible Assets - Schedule of Goodwill (Details) - USD ($)
$ in Millions
 2 Months Ended 4 Months Ended 12 Months Ended
Dec. 31, 2021
Oct. 19, 2021
Jun. 30, 2021
Jun. 30, 2020
Goodwill [Roll Forward]        
Goodwill, beginning balance $ 677.4 $ 681.5 $ 522.6 $ 511.6
Translation adjustment (13.7) (5.0) 16.0 (6.1)
Goodwill, ending balance 1,662.6 677.4 681.5 522.6
Capintec        
Goodwill [Roll Forward]        
Goodwill acquired during period       6.0
Premium Analyse        
Goodwill [Roll Forward]        
Goodwill acquired during period       4.3
Selmic        
Goodwill [Roll Forward]        
Goodwill acquired during period       2.7
AWST        
Goodwill [Roll Forward]        
Goodwill acquired during period       4.1
SNC        
Goodwill [Roll Forward]        
Goodwill acquired during period     130.2  
Biodex        
Goodwill [Roll Forward]        
Goodwill acquired during period     11.1  
Dosimetrics        
Goodwill [Roll Forward]        
Goodwill acquired during period     1.6  
Dosimetry Badge        
Goodwill [Roll Forward]        
Goodwill acquired during period   0.9    
Mirion TopCo        
Goodwill [Roll Forward]        
Goodwill acquired during period 1,639.0      
CHP        
Goodwill [Roll Forward]        
Goodwill acquired during period 1.5      
Safeline        
Goodwill [Roll Forward]        
Goodwill acquired during period 0.8      
CIRS        
Goodwill [Roll Forward]        
Goodwill acquired during period 35.0      
Medical        
Goodwill [Roll Forward]        
Goodwill, beginning balance 250.0 249.5 106.8 96.7
Translation adjustment 0.0 (0.4) (0.2) 0.0
Goodwill, ending balance 712.5 250.0 249.5 106.8
Medical | Capintec        
Goodwill [Roll Forward]        
Goodwill acquired during period       6.0
Medical | Premium Analyse        
Goodwill [Roll Forward]        
Goodwill acquired during period       0.0
Medical | Selmic        
Goodwill [Roll Forward]        
Goodwill acquired during period       0.0
Medical | AWST        
Goodwill [Roll Forward]        
Goodwill acquired during period       4.1
Medical | SNC        
Goodwill [Roll Forward]        
Goodwill acquired during period     130.2  
Medical | Biodex        
Goodwill [Roll Forward]        
Goodwill acquired during period     11.1  
Medical | Dosimetrics        
Goodwill [Roll Forward]        
Goodwill acquired during period     1.6  
Medical | Dosimetry Badge        
Goodwill [Roll Forward]        
Goodwill acquired during period   0.9    
Medical | Mirion TopCo        
Goodwill [Roll Forward]        
Goodwill acquired during period 675.2      
Medical | CHP        
Goodwill [Roll Forward]        
Goodwill acquired during period 1.5      
Medical | Safeline        
Goodwill [Roll Forward]        
Goodwill acquired during period 0.8      
Medical | CIRS        
Goodwill [Roll Forward]        
Goodwill acquired during period 35.0      
Industrial        
Goodwill [Roll Forward]        
Goodwill, beginning balance 427.4 432.0 415.8 414.9
Translation adjustment (13.7) (4.6) 16.2 (6.1)
Goodwill, ending balance 950.1 427.4 432.0 415.8
Industrial | Capintec        
Goodwill [Roll Forward]        
Goodwill acquired during period       0.0
Industrial | Premium Analyse        
Goodwill [Roll Forward]        
Goodwill acquired during period       4.3
Industrial | Selmic        
Goodwill [Roll Forward]        
Goodwill acquired during period       2.7
Industrial | AWST        
Goodwill [Roll Forward]        
Goodwill acquired during period       $ 0.0
Industrial | SNC        
Goodwill [Roll Forward]        
Goodwill acquired during period     0.0  
Industrial | Biodex        
Goodwill [Roll Forward]        
Goodwill acquired during period     0.0  
Industrial | Dosimetrics        
Goodwill [Roll Forward]        
Goodwill acquired during period     $ 0.0  
Industrial | Dosimetry Badge        
Goodwill [Roll Forward]        
Goodwill acquired during period   $ 0.0    
Industrial | Mirion TopCo        
Goodwill [Roll Forward]        
Goodwill acquired during period 963.8      
Industrial | CHP        
Goodwill [Roll Forward]        
Goodwill acquired during period 0.0      
Industrial | Safeline        
Goodwill [Roll Forward]        
Goodwill acquired during period 0.0      
Industrial | CIRS        
Goodwill [Roll Forward]        
Goodwill acquired during period $ 0.0