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Income Taxes - Summary of Income Tax Contingencies (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
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Balance, beginning of period | $ 6.5 | $ 5.0 | $ 0.8 | $ 13.9
Increases resulting from the Mirion Business Combination | 6.5 | 0.0 | 0.0 | 0.0
Current year additions to positions | 0.1 | 1.5 | 2.6 | 0.0
Additions from other business combinations | 0.2 | 0.0 | 1.7 | 0.0
Lapse of applicable statute of limitations | 0.0 | 0.0 | 0.1 | 13.1
Reductions to prior year positions | (0.2) | 0.0 | 0.0 | 0.0
Foreign currency translation adjustments | 0.0 | 0.0 | 0.0 | 0.0
Balance, end of period | 6.6 | 6.5 | $ 5.0 | $ 0.8
GSAH |  |  |  |
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |  |
Balance, beginning of period | $ 0.0 |  |  |
Balance, end of period |  | $ 0.0 |  |

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- Definition Amount of unrecognized tax benefits. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 10B -URI http://asc.fasb.org/extlink&oid=123427490&loc=SL37586934-109318 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121826272&loc=SL6600010-109319 + Details
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