Represents the number of parking spaces

No definition available.

Name:	mcri_NumberOfParkingSpaces
Namespace Prefix:	mcri_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Anniversary years in which lease with related party annual rent amount is subject to cost of living adjustment increases.

+ References

No definition available.

+ Details

Name:	mcri_RelatedPartyTransactionLeaseAnniversaryTermSubjectToRentColaAdjustment
Namespace Prefix:	mcri_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the commencing, minimum annual amount for rent under a lease agreement.

+ References

No definition available.

+ Details

Name:	mcri_RelatedPartyTransactionMinimumAnnualRent
Namespace Prefix:	mcri_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the number of terms for which the lease can be renewed.

+ References

No definition available.

+ Details

Name:	mcri_RelatedPartyTransactionOptionToRenewLeaseNumberOfLeaseTerms
Namespace Prefix:	mcri_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount due to related party in the event that the lease is not renewed.

+ References

No definition available.

+ Details

Name:	mcri_RelatedPartyTransactionSubsequentObligationDueWithoutLeaseRenewal
Namespace Prefix:	mcri_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Area of land held.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfLand
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Indicates (true false) whether lessee has option to extend operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-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_LesseeOperatingLeaseExistenceOfOptionToExtend
Namespace Prefix:	us-gaap_
Data Type:	xbrli:booleanItemType
Balance Type:	na
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

Amount of operating lease expense. Excludes sublease income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918638-209977

+ Details

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

- 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=121603541&loc=SL77918627-209977

+ Details

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

- Definition

Amount of lessee's right to use underlying asset under 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 (a)
-URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977

+ Details

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

- Definition

Cash payments to lessor's for use of assets under operating leases.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3536-108585

+ Details

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

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

- Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=mcri_ShoppingCenterSurfaceLotLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=mcri_ShoppingCenterDrivewayLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=mcri_RelatedPartyLeasesForBillboardAdvertisingStorageSpaceAndParkingLotSpaceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=mcri_GoldenRoadMotorInnInc.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

RELATED PARTY TRANSACTIONS (Details) $ in Thousands				3 Months Ended		9 Months Ended
RELATED PARTY TRANSACTIONS (Details) $ in Thousands	Nov. 17, 2015 USD ($)	Aug. 28, 2015 a ft² item	Sep. 30, 2004 USD ($)	Sep. 30, 2020 USD ($) ft²	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) ft²	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
RELATED PARTY TRANSACTIONS
Right of use asset				$ 14,977		$ 14,977		$ 15,574
Biggest Little Investments, L.P. (BLI) \| Parking Lot Lease
RELATED PARTY TRANSACTIONS
Rent paid				174	$ 174	522	$ 522
Operating expenses related to lease				13	6	20	19
Right of use asset				10,600		10,600
Operating lease liability				$ 10,600		$ 10,600
Biggest Little Investments, L.P. (BLI) \| Driveway Lease
RELATED PARTY TRANSACTIONS
Lease term			15 years
Area of property \| ft²				37,400		37,400
Minimum annual rent			$ 300
Anniversary years subject to cost of living adjustment rent increases			5 years
Number of terms for which the lease can be renewed \| item		3
Lease renewal option additional term		5 years
Rent paid				$ 101	94	$ 303	282
Operating expenses related to lease				8	7	17	20
Right of use asset				4,000		4,000
Operating lease liability				4,000		4,000
Affiliates \| Billboard advertising, storage space and parking lot space
RELATED PARTY TRANSACTIONS
Rent paid				$ 27	$ 48	$ 101	$ 117
Golden Road \| Parking Lot Lease \| Buildings
RELATED PARTY TRANSACTIONS
Area of land \| a		4.2
Golden Road \| Parking Lot Lease \| Land
RELATED PARTY TRANSACTIONS
Number of parking spaces \| item		300
Golden Road \| Biggest Little Investments, L.P. (BLI) \| Parking Lot Lease
RELATED PARTY TRANSACTIONS
Lease term		20 years
Minimum annual rent	$ 695
Anniversary years subject to cost of living adjustment rent increases	5 years
Lease renewal option additional term				10 years		10 years
Lessee, Operating Lease, Existence of Option to Extend [true false]						true
Amount due to related party if lease is not renewed				$ 1,600		$ 1,600
Golden Road \| Biggest Little Investments, L.P. (BLI) \| Parking Lot Lease \| Buildings
RELATED PARTY TRANSACTIONS
Area of property \| ft²		46,000
Area of land \| a		4.2