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Area of a real estate property.

No definition available.

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The net gain (loss) resulting from sales and other disposals of real estate owned for investment purposes.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
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-Name Accounting Standards Codification
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-Paragraph 28
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(7)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(b)(9)(a))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(14)(d))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-SubTopic 360
-Topic 944
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479638/944-360-45-3

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
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-Topic 944
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479638/944-360-45-4

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
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-Topic 944
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479607/944-360-50-1

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The number of real estate properties owned as of the balance sheet date.

No definition available.

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Data Type:	xbrli:integerItemType
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The number of units in a real estate property owned as of the balance sheet date.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
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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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 976
-SubTopic 310
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482856/976-310-50-1

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Data Type:	xbrli:stringItemType
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Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
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Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=dhc_SeniorLivingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementGeographicalAxis=dhc_PennsylvaniaAndSouthCarolinaMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	srt_StatementGeographicalAxis=stpr_TN
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Name:	srt_StatementGeographicalAxis=stpr_VA
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Data Type:	na
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Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=dhc_MedicalOfficeBuildingMember
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Data Type:	na
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Name:	srt_StatementGeographicalAxis=stpr_SC
Namespace Prefix:
Data Type:	na
Balance Type:
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Namespace Prefix:
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