XML 103 R88.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Leases - Narrative (Details) - USD ($) $ in Thousands | 7 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2021 | Dec. 31, 2020
Lessee, Lease, Description [Line Items] |  |  |
ROU operating lease liabilities | $ 48,037 | $ 44,070 | $ 48,037
Operating rental payments |  | 13,098 | 13,246
ROU finance lease assets | 15,800 | 13,800 | 15,800
Company's Headquarter | Operating Lease Arrangement |  |  |
Lessee, Lease, Description [Line Items] |  |  |
ROU operating lease liabilities | $ 3,800 | 2,900 | 3,800
Operating rental payments |  | 1,300 | $ 700
COVID-19 | Company's Headquarter | Operating Lease Arrangement |  |  |
Lessee, Lease, Description [Line Items] |  |  |
Percentage of reduction on rental payments | 20.00% |  |
Period for reduction of rental payments | 90 days |  |
COVID-19 | Services |  |  |
Lessee, Lease, Description [Line Items] |  |  |
Impairment of ROU asset |  | $ 200 |

X
- Definition Operating Lease, Deferral Period Of Rental Payments + References No definition available. + Details
Name: | mg_OperatingLeaseDeferralPeriodOfRentalPayments
Namespace Prefix: | mg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Operating Lease, Percentage Of Reduction Of Rental Payments + References No definition available. + Details
Name: | mg_OperatingLeasePercentageOfReductionOfRentalPayments
Namespace Prefix: | mg_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after accumulated amortization, of right-of-use asset from finance lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977 + Details
Name: | us-gaap_FinanceLeaseRightOfUseAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_LesseeLeaseDescriptionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of loss from impairment of right-of-use asset from operating lease. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 25 -Paragraph 6 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123399704&loc=SL77918431-209957 + Details
Name: | us-gaap_OperatingLeaseImpairmentLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Present value of lessee's discounted obligation for lease payments from operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977 + Details
Name: | us-gaap_OperatingLeaseLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918643-209977 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(1) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 + Details
Name: | us-gaap_OperatingLeasePayments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionAxis=mg_OperatingLeaseArrangementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnusualOrInfrequentItemAxis=mg_COVID19PandemicMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mg_ServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |