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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 | Oct. 20, 2021 | Jun. 30, 2019
Goodwill [Roll Forward] |  |  |  |  |  |
Goodwill, beginning balance | $ 1,662.6 | $ 677.4 | $ 681.5 | $ 522.6 | $ 0.0 | $ 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, beginning balance |  |  |  |  | 1,639.0 |
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 | 712.5 | 250.0 | 249.5 | 106.8 | 0.0 | 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 | 950.1 | 427.4 | 432.0 | 415.8 | $ 0.0 | $ 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 |  |  |  |  |

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