Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Narrative (Details)

v3.22.4
Stock-Based Compensation - Narrative (Details)
$ / shares in Units, $ in Millions
 4 Months Ended 12 Months Ended
Oct. 20, 2021
$ / shares
Oct. 19, 2021
shares
Jun. 17, 2021
$ / shares
shares
Oct. 19, 2021
shares
Dec. 31, 2022
USD ($)
installment
shares
Jun. 30, 2021
USD ($)
shares
Jun. 30, 2020
USD ($)
Jan. 01, 2022
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Profit interests, percent     50.00%          
Share-based compensation arrangement by share-based payment award, vesting, number of Installments | installment         4      
Unrecognized compensation expense | $         $ 16.1      
Expected period for recognition         1 year 2 months 12 days      
Profit Interest 1                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Profit interests (in shares)     3,200,000          
Profits interest, threshold price (in dollars per share) | $ / shares $ 12   $ 12          
Profit Interest 2                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Profit interests (in shares)     2,000,000          
Profits interest, threshold price (in dollars per share) | $ / shares 14   $ 14          
Profit Interest 3                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Profit interests (in shares)     3,000,000.0          
Profits interest, threshold price (in dollars per share) | $ / shares $ 16   $ 16          
Lawrence Kingsley (Chairman of Board)                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Shares issued (in shares)     4,200,000          
Thomas Logan (CEO)                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Shares issued (in shares)     3,200,000          
Brian Schopfer (CFO)                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Shares issued (in shares)     700,000          
Minimum                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Number of trading days for determining the value per share 20 days              
Maximum                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Number of trading days for determining the value per share 30 days              
Class A Common Stock                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Stock-based compensation expense | $         $ 0.3      
2021 Omnibus Incentive Plan                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Number of shares available for grant (in shares)         23,554,298      
2021 Omnibus Incentive Plan | Class A Common Stock                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Common stock, capital shares reserved for future issuance (in shares)   19,952,329   19,952,329       25,938,028
Common stock outstanding, ownership percentage   3.00%   3.00%        
Common stock, outstanding share threshold (in shares)   9,976,164   9,976,164        
RSUs                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Target percentage         100.00%      
Expected period for recognition         1 year 8 months 12 days      
Restricted Stock                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Requisite service period   4 years            
Stock-based compensation expense | $           $ 0.0 $ 0.2  
Shares issued (in shares)       0   0    
Shares reissued (in shares)       0   144,219    
Restricted Stock | Minimum                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Requisite service period         3 years      
Restricted Stock | Maximum                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Requisite service period         5 years      
Restricted Stock | Ordinary A shares of Mirion TopCo common stock                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Shares issued (in shares)   1,483,795            
PSUs                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Share-based compensation arrangement by share-based payment award, award vesting period         3 years      
Profit interests, percent     50.00%          
Expected period for recognition         2 years 1 month 6 days      
PSUs | Minimum                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Variable range, percentage   0.00%   0.00%        
PSUs | Maximum                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Variable range, percentage   200.00%   200.00%