Cash Retained in Suspension of Dividend

No definition available.

Name:	mic_CashRetainedinSuspensionofDividend
Namespace Prefix:	mic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Debt Covenant, Debt to EBITDA Ratio, Net

+ References

No definition available.

+ Details

Name:	mic_DebtCovenantDebttoEBITDARatioNet
Namespace Prefix:	mic_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

[Line Items] for Impact of COVID-19 [Table]

+ References

No definition available.

+ Details

Name:	mic_ImpactofCOVID19LineItems
Namespace Prefix:	mic_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Liquidity Available, Cash On Hand And Revolving Credit Facilities

+ References

No definition available.

+ Details

Name:	mic_LiquidityAvailableCashOnHandAndRevolvingCreditFacilities
Namespace Prefix:	mic_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3044-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_CashAndCashEquivalentsAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromLongTermLinesOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_CorporateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=mic_AtlanticAviationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Impact of COVID-19 - Narrative (Details) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
Impact of COVID-19 - Narrative (Details) $ in Millions	Mar. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	May 04, 2020 USD ($)	May 01, 2020 USD ($)	Mar. 17, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)
Impact of COVID-19 [Line Items]
Cash and cash equivalents	$ 1,156	$ 1,156				$ 300	$ 357	$ 603
Letters of credit	12	12
Revolving Credit Facility
Impact of COVID-19 [Line Items]
Proceeds from line of credit	874
MIC Corporate \| Revolving Credit Facility
Impact of COVID-19 [Line Items]
Proceeds from line of credit	599	599
Atlantic Aviation \| Revolving Credit Facility
Impact of COVID-19 [Line Items]
Proceeds from line of credit	$ 275	$ 275
Subsequent Event
Impact of COVID-19 [Line Items]
Liquidity available, cash on hand and revolving credit facilities					$ 1,530
Subsequent Event \| Atlantic Aviation
Impact of COVID-19 [Line Items]
Letters of credit				$ 10
Forecast
Impact of COVID-19 [Line Items]
Cash retained in suspension of dividend			$ 260
Maximum \| Subsequent Event \| Atlantic Aviation
Impact of COVID-19 [Line Items]
Debt Covenant, Debt to EBITDA Ratio, Net				5.5