XML 134 R103.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Detail) - USD ($) | Dec. 31, 2021 | Jun. 30, 2021 | Jun. 30, 2020
--- | --- | --- | ---
Liabilities |  |  |
Private placement warrants | $ 21,200,000 |  |
Fair Value, Recurring | Level 1 |  |  |
Liabilities |  |  |
Public warrants | 46,900,000 | $ 0 | $ 0
Private placement warrants | 0 | 0 | 0
Fair Value, Recurring | Level 1 | Cash, cash equivalents, and restricted cash |  |  |
Assets |  |  |
Assets | 85,300,000 | 102,400,000 | 120,000,000.0
Fair Value, Recurring | Level 1 | Discretionary retirement plan |  |  |
Assets |  |  |
Assets | 3,700,000 | 3,400,000 | 2,400,000
Liabilities |  |  |
Discretionary retirement plan | 3,700,000 | 3,400,000 | 2,400,000
Fair Value, Recurring | Level 2 |  |  |
Liabilities |  |  |
Public warrants | 0 |  |
Private placement warrants | 21,200,000 |  |
Fair Value, Recurring | Level 2 | Cash, cash equivalents, and restricted cash |  |  |
Assets |  |  |
Assets | 0 | 0 | 0
Fair Value, Recurring | Level 2 | Discretionary retirement plan |  |  |
Assets |  |  |
Assets | 800,000 | 800,000 | 1,100,000
Liabilities |  |  |
Discretionary retirement plan | 800,000 | 800,000 | 1,100,000
Fair Value, Recurring | Level 3 |  |  |
Liabilities |  |  |
Public warrants | 0 |  |
Private placement warrants | 0 |  |
Fair Value, Recurring | Level 3 | Cash, cash equivalents, and restricted cash |  |  |
Assets |  |  |
Assets | 0 | 0 | 0
Fair Value, Recurring | Level 3 | Discretionary retirement plan |  |  |
Assets |  |  |
Assets | 0 | 0 | 0
Liabilities |  |  |
Discretionary retirement plan | $ 0 | $ 0 | $ 0

X
- Definition Warrant liabilities. + References No definition available. + Details
Name: | mir_WarrantLiabilityPrivatePlacement
Namespace Prefix: | mir_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Warrant liability public warrants. + References No definition available. + Details
Name: | mir_WarrantLiabilityPublicWarrants
Namespace Prefix: | mir_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AssetsFairValueDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LiabilitiesFairValueDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=mir_CashCashEquivalentsAndRestrictedCashMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=mir_DiscretionaryRetirementPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |