Indebtedness - Schedule of Secured and Other Debt (Details) $ in Thousands	Dec. 31, 2022 USD ($) property	Dec. 31, 2021 USD ($)
Debt Instrument
Principal Balance	$ 30,177	$ 69,713
Net book value of collateral	4,864,191	5,075,749
Unamortized discount (premium) and debt issuance costs, net	3,047,877
Secured Debt
Debt Instrument
Principal Balance	$ 30,068	69,135
Number of Properties as Collateral \| property	4
Net book value of collateral	$ 58,503	118,342
Secured Debt \| Mortgage notes 6.28% maturing July 2022
Debt Instrument
Principal Balance	$ 0	11,120
Interest rate (as a percent)	6.28%
Number of Properties as Collateral \| property	0
Net book value of collateral	$ 0	23,525
Secured Debt \| Mortgage notes 4.85% maturing October 2022
Debt Instrument
Principal Balance	$ 0	10,479
Interest rate (as a percent)	4.85%
Number of Properties as Collateral \| property	0
Net book value of collateral	$ 0	19,211
Secured Debt \| Mortgage notes 5.75% maturing October 2022
Debt Instrument
Principal Balance	$ 0	15,456
Interest rate (as a percent)	5.75%
Number of Properties as Collateral \| property	0
Net book value of collateral	$ 0	19,099
Secured Debt \| Mortgage notes 6.64% maturing June 2023
Debt Instrument
Principal Balance	$ 14,732	15,204
Interest rate (as a percent)	6.64%
Number of Properties as Collateral \| property	1
Net book value of collateral	$ 24,645	24,593
Secured Debt \| Mortgage notes 4.44% maturing July 2043
Debt Instrument
Principal Balance	$ 9,997	10,240
Interest rate (as a percent)	4.44%
Number of Properties as Collateral \| property	1
Net book value of collateral	$ 13,234	13,387
Secured Debt \| Capital leases 7.70% maturing in April 2026
Debt Instrument
Principal Balance	$ 5,339	6,636
Interest rate (as a percent)	7.70%
Number of Properties as Collateral \| property	2
Net book value of collateral	$ 20,624	18,527
Secured Debt \| Mortgage notes 7.49% maturing in January 2022
Debt Instrument
Unamortized discount (premium) and debt issuance costs, net	$ (109)	$ (578)

Represents the number of real estate properties serving as a collateral for debt, as of the balance sheet date.

No definition available.

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

- Definition

Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower and amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

+ References

No definition available.

+ Details

Name:	dhc_SecuredDebtAndFinanceLeaseObligations
Namespace Prefix:	dhc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(2)
-URI https://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1D
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399

+ Details

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

- Definition

Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(d))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dhc_Mortgages6.28PercentDueJuly2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dhc_Mortgage4.85PercentDueOctober2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dhc_Mortgage5.75PercentDueOctober2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dhc_Mortgage6.64PercentDueJune2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dhc_Mortgage4.44PercentDueJuly2043Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dhc_Capitallease7.70PercentDueApril2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dhc_Mortgage7.49PercentDueJanuary2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: