Represents the useful life of the cost of improvements.

No definition available.

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

- Definition

Represents the number of parking spaces

+ References

No definition available.

+ Details

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

- Definition

Represents the amount of operating expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

No definition available.

+ Details

Name:	mcri_OperatingExpensesRelatedToLease
Namespace Prefix:	mcri_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

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=77888426&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

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_RelatedPartyTransactionAxis=mcri_ShoppingCenterDrivewayLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- 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_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:

RELATED PARTY TRANSACTIONS (Details) $ in Thousands			3 Months Ended		9 Months Ended
RELATED PARTY TRANSACTIONS (Details) $ in Thousands	Aug. 28, 2015 USD ($) ft² a item	Sep. 30, 2004 USD ($)	Sep. 30, 2018 USD ($) ft²	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) ft²	Sep. 30, 2017 USD ($)	Nov. 17, 2015 USD ($)
Driveway Lease
RELATED PARTY TRANSACTIONS
Operating expenses related to lease		$ 1,350
Biggest Little Investments, L.P. (BLI) \| Parking Lot Lease
RELATED PARTY TRANSACTIONS
Number of parking spaces \| item	300
Minimum annual rent							$ 695
Anniversary years subject to cost of living adjustment rent increases	5 years
Lease renewal option additional term	10 years
Amount due to related party if lease is not renewed	$ 1,600
Operating expenses related to lease			$ 6	$ 15	$ 15	$ 23
Lease rent paid			$ 174	174	$ 522	522
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
Operating expenses related to lease		$ 2,000	$ 6	8	$ 15	19
Cost of improvements, useful life		15 years
Lease rent paid			94	94	282	282
Affiliates \| Billboard advertising, storage space and parking lot space
RELATED PARTY TRANSACTIONS
Lease rent paid			$ 42	$ 36	$ 109	$ 96
Golden Road \| Biggest Little Investments, L.P. (BLI) \| Parking Lot Lease
RELATED PARTY TRANSACTIONS
Lease term	20 years
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