Number Of Properties Included In Joint Venture

No definition available.

Name:	dhc_NumberOfPropertiesIncludedInJointVenture
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Data Type:	xbrli:integerItemType
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Period Type:	instant

- Definition

The number of real estate properties owned by the entity, which are classified as held for sale as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	dhc_NumberOfRealEstatePropertiesHeldForSale
Namespace Prefix:	dhc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of Real Estate Properties Sold

+ References

No definition available.

+ Details

Name:	dhc_NumberofRealEstatePropertiesSold
Namespace Prefix:	dhc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Real Estate Properties Under Agreement

+ References

No definition available.

+ Details

Name:	dhc_NumberofRealEstatePropertiesUnderAgreement
Namespace Prefix:	dhc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the aggregate purchase price excluding acquisition costs of real estate properties acquired or agreed to be acquired by the entity.

+ References

No definition available.

+ Details

Name:	dhc_RealEstateAggregatePurchasePrice
Namespace Prefix:	dhc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the aggregate sales price excluding closing costs, of real estate properties sold by the entity.

+ References

No definition available.

+ Details

Name:	dhc_RealEstateAggregateSalesPrice
Namespace Prefix:	dhc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-SubTopic 10
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The charge against earnings resulting from the write down of long lived assets other than goodwill due to the difference between the carrying value and lower fair value.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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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_PropertyPlantAndEquipmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of investments in land and buildings held for sale, excluding real estate considered to be inventory of the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
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+ Details

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

- Details

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- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=dhc_SeniorLivingCommunityMember
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- Details

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Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupHeldforsaleNotDiscontinuedOperationsMember
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=dhc_LifeScienceBuildingMember
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Data Type:	na
Balance Type:
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- Details

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Data Type:	na
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- Details

Name:	srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=dhc_LandParcelMember
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Data Type:	na
Balance Type:
Period Type:

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Real Estate Properties - Narrative (Details) $ in Thousands		1 Months Ended			3 Months Ended
Real Estate Properties - Narrative (Details) $ in Thousands	May 06, 2020 USD ($) property	May 07, 2020 USD ($) property	Feb. 29, 2020 property	Jan. 31, 2020 USD ($)	Mar. 31, 2020 USD ($) state building property	Mar. 31, 2019 USD ($)
Real Estate Properties
Number of real estate properties					416
Number of states in which properties are located \| state					38
Impairment of assets \| $					$ 11,234	$ 6,206
Medical Office Buildings
Real Estate Properties
Number of real estate properties held for sale					10
Number of real estate properties sold			1
Senior Living Communities
Real Estate Properties
Number of real estate properties held for sale					14
Held-for-sale or Disposed of by Sale \| Medical Office Buildings
Real Estate Properties
Number of real estate properties					2
Impairment recovery \| $					$ 287
Held-for-sale or Disposed of by Sale \| Senior Living Communities
Real Estate Properties
Number of real estate properties					2
Impairment recovery \| $					$ 565
Held-for-sale
Real Estate Properties
Number of real estate properties held for sale					24
Amount under agreement to sell \| $					$ 287,397
Held-for-sale \| Medical Office Buildings
Real Estate Properties
Number of real estate properties					6
Held-for-sale \| Senior Living Communities
Real Estate Properties
Number of real estate properties					5
Held-for-sale, Not Discontinued Operations \| Medical Office Buildings
Real Estate Properties
Number of real estate properties					7
Impairment of assets \| $					$ 6,505
Disposed of by Sale, Not Discontinued Operations
Real Estate Properties
Number of real estate properties sold \| building					8
Aggregate sale price \| $					$ 17,604
Joint Venture
Real Estate Properties
Ownership percentage					55.00%
Joint Venture \| Life Science Building
Real Estate Properties
Number of properties included in joint venture					1
Tempe, AZ \| Land Parcel
Real Estate Properties
Aggregate purchase price \| $				$ 2,600
Subsequent Event
Real Estate Properties
Number of real estate properties sold		3
Aggregate sale price \| $	$ 164,047	$ 47,000
Amount under agreement to sell	27