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

No definition available.

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

Amount of amortization and adjustments to revenue from tenants for intangible assets and liabilities, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

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

Amount of amortization and adjustments to revenue from tenants for intangible assets and liabilities, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

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

Amount of amortization and adjustments to revenue from tenants for intangible assets and liabilities, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

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

Amount of amortization and adjustments to revenue from tenants for intangible assets and liabilities, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

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

- References

No definition available.

Name:	mrc_AcquiredIntangiblesAssetsNetAmortizationExpenseAndAdjustmentsFiscalYearMaturityAbstract
Namespace Prefix:	mrc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_LeasesAcquiredInPlaceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=mrc_AboveMarketLeaseAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=mrc_BelowMarketLeaseLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: