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Stock-Based Compensation - Narrative (Details) $ / shares in Units, $ in Millions |  |  |  | 4 Months Ended | 12 Months Ended |  |
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Oct. 20, 2021 $ / shares shares | Oct. 19, 2021 shares | Jun. 17, 2021 shares | Oct. 19, 2021 shares | Dec. 31, 2023 USD ($) installment $ / shares shares | Dec. 31, 2022 USD ($) $ / shares shares | Jun. 30, 2021 USD ($) shares | Jan. 01, 2023 shares | Dec. 31, 2021 $ / 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 | $ |  |  |  |  | $ 2.8 |  |  |  |
Expected period for recognition |  |  |  |  | 9 months 18 days |  |  |  |
Common stock, shares outstanding (in shares) |  |  |  |  | 18,750,000 |  |  |  |
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 | $ 14 |  |  | $ 16
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 |  |  |  |  |  |  |  |
Profit Interest 3 |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Profit interests (in shares) |  |  | 3,000,000 |  |  |  |  |  |
Profits interest, threshold price (in dollars per share) | $ / shares | $ 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 | $ 0.3 |  |  |
Common stock, shares outstanding (in shares) | 18,750,000 |  |  |  | 218,177,832 | 200,298,834 |  |  |
Class A Common Stock | 2021 Omnibus Incentive Plan |  |  |  |  |  |  |  |  |
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 |  |  |  | 31,946,993 |
Common stock outstanding, ownership percentage |  | 3.00% |  | 3.00% |  |  |  |  |
Common stock, shares outstanding (in shares) |  | 9,976,164 |  | 9,976,164 |  |  |  |  |
2021 Omnibus Incentive Plan |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Number of shares available for grant (in shares) |  |  |  |  | 28,805,002 |  |  |  |
RSUs |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Target percentage |  |  |  |  | 100.00% | 200.00% |  |  |
Expected period for recognition |  |  |  |  | 1 year 2 months 12 days |  |  |  |
Restricted Stock |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Stock-based compensation expense | $ |  |  |  |  |  |  | $ 0.0 |  |
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] |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, award vesting period |  | 4 years |  |  |  |  |  |  |
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 |  |  |  |  | 1 year 2 months 12 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% |  |  |  |  |
Founder Shares |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Share-based compensation arrangement by share-based payment award, award vesting period | 5 years |  |  |  |  |  |  |  |
Founder Shares | Profit Interest 1 |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Profits interest, threshold price (in dollars per share) | $ / shares | $ 12 |  |  |  |  |  |  |  |
Founder Shares | Profit Interest 2 |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Profits interest, threshold price (in dollars per share) | $ / shares | 14 |  |  |  |  |  |  |  |
Founder Shares | Profit Interest 3 |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Profits interest, threshold price (in dollars per share) | $ / shares | $ 16 |  |  |  |  |  |  |  |
Founder Shares | Minimum |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Number of trading days for determining the value per share | 20 days |  |  |  |  |  |  |  |
Founder Shares | Maximum |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Number of trading days for determining the value per share | 30 days |  |  |  |  |  |  |  |

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