Annual rent escalating from year one through year ten.

No definition available.

Name:	mgm_AnnualRentEscalatingFromYearOneThroughYearTen
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual rent escalator after year fifteen.

+ References

No definition available.

+ Details

Name:	mgm_AnnualRentEscalatorAfterYearFifteen
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual rent escalator after year ten.

+ References

No definition available.

+ Details

Name:	mgm_AnnualRentEscalatorAfterYearTen
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual rent escalator cap after year fifteen.

+ References

No definition available.

+ Details

Name:	mgm_AnnualRentEscalatorCapAfterYearFifteen
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual rent escalator cap after year ten.

+ References

No definition available.

+ Details

Name:	mgm_AnnualRentEscalatorCapAfterYearTen
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual rent escalator from year one through year fifteen.

+ References

No definition available.

+ Details

Name:	mgm_AnnualRentEscalatorFromYearOneThroughYearFifteen
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Business combination retaining ownership interest.

+ References

No definition available.

+ Details

Name:	mgm_BusinessCombinationRetainingOwnershipInterest
Namespace Prefix:	mgm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Lessee operating lease rolling period.

+ References

No definition available.

+ Details

Name:	mgm_LesseeOperatingLeaseRollingPeriod
Namespace Prefix:	mgm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Lessee operating lease succeeding period.

+ References

No definition available.

+ Details

Name:	mgm_LesseeOperatingLeaseSucceedingPeriod
Namespace Prefix:	mgm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Minority interest ownership percentage in consolidated subsidiary.

+ References

No definition available.

+ Details

Name:	mgm_MinorityInterestOwnershipPercentageInConsolidatedSubsidiary
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Minority interest ownership percentage in unconsolidated affiliate.

+ References

No definition available.

+ Details

Name:	mgm_MinorityInterestOwnershipPercentageInUnconsolidatedAffiliate
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of integrated casino.

+ References

No definition available.

+ Details

Name:	mgm_NumberOfIntegratedCasino
Namespace Prefix:	mgm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of renewal periods, exercisable at option.

+ References

No definition available.

+ Details

Name:	mgm_NumberOfRenewalPeriodsExercisableAtOption
Namespace Prefix:	mgm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating partnership units received.

+ References

No definition available.

+ Details

Name:	mgm_OperatingPartnershipUnitsReceived
Namespace Prefix:	mgm_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Organization disclosure.

+ References

No definition available.

+ Details

Name:	mgm_OrganizationDisclosureLineItems
Namespace Prefix:	mgm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percent interest in a less than hundred percent owned consolidated affiliate.

+ References

No definition available.

+ Details

Name:	mgm_PercentInterestInALessThanHundredPercentOwnedConsolidatedAffiliate
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Required minimum ownership percentage in beneficial ownership to entitle majority of voting power.

+ References

No definition available.

+ Details

Name:	mgm_RequiredMinimumOwnershipPercentageInBeneficialOwnershipToEntitleMajorityOfVotingPower
Namespace Prefix:	mgm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionSharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120321790&loc=d3e6927-128479

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477

+ Details

Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Description of voting rights of common stock. Includes eligibility to vote and votes per share owned. Include also, if any, unusual voting rights.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Name:	us-gaap_CommonStockVotingRights
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

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

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of subsidiary's or equity investee's stock owned by parent company after stock transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockPercentageOfOwnershipAfterTransaction
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of shares issued in lieu of cash for services contributed to the entity. Number of shares includes, but is not limited to, shares issued for services contributed by vendors and founders.

+ References

No definition available.

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesIssuedForServices
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 5A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121559654&loc=SL6759159-111685

+ Details

Name:	us-gaap_VariableInterestEntityOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mgm_CityCenterHoldingsLLCAsInvesteeMember
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_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mgm_BetMGMLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherOwnershipInterestsByNameAxis=mgm_InfinityWorldDevelopmentCorpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherOwnershipInterestsByNameAxis=mgm_EntainPLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=mgm_BellagioBREITVentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=mgm_MGPBREITVentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=mgm_VICIPropertiesIncMember
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:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=mgm_BlackstoneRealEstateIncomeTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=mgm_AriaAndVdaraMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=mgm_SubsidiaryOfBlackstoneRealEstateIncomeTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=mgm_MGMChinaHoldingsLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=mgm_NonGuarantorMGPSubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CapitalUnitsByClassAxis=us-gaap_CapitalUnitClassAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CapitalUnitsByClassAxis=us-gaap_CapitalUnitClassBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=mgm_MGMGrowthPropertiesLimitedLiabilityCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Organization - Additional Information (Detail) $ / shares in Units, $ in Millions			6 Months Ended
	Aug. 04, 2021 USD ($) Renewal_period $ / shares shares	Jun. 30, 2021 USD ($) Renewal_period	Jun. 30, 2021 Property Segment	Sep. 30, 2021	Dec. 31, 2020
Organization Disclosure [Line Items]
Number of reportable segments \| Segment			3
CityCenter Holdings LLC As Investee [Member]
Organization Disclosure [Line Items]
Percentage ownership interest		50.00%	50.00%		50.00%
CityCenter Holdings LLC As Investee [Member] \| Scenario Forecast [Member]
Organization Disclosure [Line Items]
Percentage ownership interest				100.00%
BetMGM LLC [Member]
Organization Disclosure [Line Items]
Percentage ownership interest		50.00%	50.00%		50.00%
Infinity World Development Corp [Member] \| CityCenter Holdings LLC As Investee [Member]
Organization Disclosure [Line Items]
Cash consideration		$ 2,125
Percentage ownership interest		50.00%	50.00%
Entain plc [Member] \| BetMGM LLC [Member]
Organization Disclosure [Line Items]
Percentage ownership interest		50.00%	50.00%
Bellagio BREIT Venture [Member]
Organization Disclosure [Line Items]
Percentage of minority interest		5.00%	5.00%
MGP BREIT Venture [Member]
Organization Disclosure [Line Items]
Partnership interest			50.10%
Percentage of minority interest		49.90%	49.90%
VICI Properties, Inc [Member] \| Subsequent Event [Member]
Organization Disclosure [Line Items]
Shares newly issued \| shares	1.366
Operating partnership units received \| shares	1.366
Fixed exchange ratio, share price \| $ / shares	$ 43
Cash consideration	$ 4,400
Ownership interest	$ 370
Lease agreement initial lease term	25 years
Number of renewal periods, exercisable at option \| Renewal_period	3
Lease agreement renewal period	10 years
Annual rent	$ 860
Annual rent escalating from year one through year ten	2.00%
Annual rent escalator after year ten	2.00%
Annual rent escalator cap after year ten	3.00%
Blackstone Real Estate Income Trust [Member] \| Aria and Vdara [Member]
Organization Disclosure [Line Items]
Cash consideration		$ 3,890
Lease agreement initial lease term		30 years	30 years
Number of renewal periods, exercisable at option \| Renewal_period		3
Lease agreement renewal period		10 years	10 years
Annual rent		$ 215
Annual rent escalator from year one through year fifteen		2.00%
Annual rent escalator after year fifteen		2.00%
Annual rent escalator cap after year fifteen		3.00%
Lease rolling period		5 years
Lease succeeding period		1 year
Subsidiary of Blackstone Real Estate Income Trust [Member] \| Bellagio BREIT Venture [Member]
Organization Disclosure [Line Items]
Percentage of ownership interest			95.00%
MGM China [Member]
Organization Disclosure [Line Items]
Percentage ownership interest			56.00%
Number of integrated casino \| Property			2
Non-Guarantor MGP Subsidiaries [Member] \| Class A shares [Member]
Organization Disclosure [Line Items]
Common stock voting rights			one vote per share
Non-Guarantor MGP Subsidiaries [Member] \| Class B shares [Member]
Organization Disclosure [Line Items]
Common stock voting rights			Class B share, is entitled to an amount of votes representing a majority of the total voting power of MGP’s shares so long as the Company and its controlled affiliates’ (excluding MGP) aggregate beneficial ownership of the combined economic interests in MGP and the Operating Partnership does not fall below 30%.
MGM Growth Properties LLC [Member]
Organization Disclosure [Line Items]
Minimum ownership percentage required for majority voting interest			30.00%
Partnership interest			41.60%
Percentage of minority interest		58.40%	58.40%