Name:	mrc_DisposalGroupIncludingDiscontinuedOperationAccumulatedAmortization
Namespace Prefix:	mrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of accumulated depreciation for physical assets used in the normal conduct of business to produce goods and services attributable to disposal group held for sale or disposed of.

No definition available.

Name:	mrc_DisposalGroupIncludingDiscontinuedOperationAccumulatedDepreciation
Namespace Prefix:	mrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount classified as building, fixtures and improvements attributable to disposal group held for sale or disposed of.

No definition available.

Name:	mrc_DisposalGroupIncludingDiscontinuedOperationBuildingFixturesAndImprovements
Namespace Prefix:	mrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as deferred rent and other liabilities attributable to disposal group held for sale or disposed of.

No definition available.

Name:	mrc_DisposalGroupIncludingDiscontinuedOperationDeferredRentAndOtherLiabilities
Namespace Prefix:	mrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount classified as due to related entities attributable to disposal group held for sale or disposed of.

No definition available.

Name:	mrc_DisposalGroupIncludingDiscontinuedOperationDueToRelatedEntities
Namespace Prefix:	mrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount classified as lease intangible assets attributable to disposal group held for sale or disposed of.

No definition available.

Name:	mrc_DisposalGroupIncludingDiscontinuedOperationIntangibleLeaseAssets
Namespace Prefix:	mrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as investments income, rents and other receivables attributable to disposal group held for sale or disposed of.

No definition available.

Name:	mrc_DisposalGroupIncludingDiscontinuedOperationInvestmentsIncomeRentsAndOtherReceivables
Namespace Prefix:	mrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as land attributable to disposal group held for sale or disposed of.

No definition available.

Name:	mrc_DisposalGroupIncludingDiscontinuedOperationLand
Namespace Prefix:	mrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as restricted cash attributable to disposal group held for sale or disposed of.

No definition available.

Name:	mrc_DisposalGroupIncludingDiscontinuedOperationRestrictedCash
Namespace Prefix:	mrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount classified as assets attributable to disposal group held for sale or disposed of.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 10
-SubTopic 20
-Topic 205
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483475/205-20-45-10

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483499/205-20-50-7

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5C
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483499/205-20-50-5C

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5B
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483499/205-20-50-5B

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-3

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483475/205-20-45-11

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

- References

No definition available.

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

Amount classified as accounts payable and accrued liabilities attributable to disposal group held for sale or disposed of.

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

Amount classified as cash and cash equivalents attributable to disposal group held for sale or disposed of.

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

Amount classified as prepaid and other assets attributable to disposal group held for sale or disposed of.

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

Amount classified as property, plant and equipment attributable to disposal group held for sale or disposed of.

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

Amount classified as liabilities attributable to disposal group held for sale or disposed of.

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

- References

No definition available.