Summary of Significant Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2024
Accounting Policies [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION. Our consolidated financial statements include the accounts of Diversified Healthcare Trust, we, us or our, and our subsidiaries, all of which are 100% owned directly or indirectly by us as of December 31, 2024. All intercompany transactions and balances with or among our consolidated subsidiaries have been eliminated.
REAL ESTATE PROPERTIES	REAL ESTATE PROPERTIES. We record properties at our cost and calculate depreciation on real estate investments on a straight line basis over estimated useful lives generally up to 40 years. We allocate the purchase prices of our properties to land, building and improvements based on determinations of the fair values of these assets assuming the properties are vacant. We determine the fair value of each property using methods similar to those used by independent appraisers, which may involve estimated cash flows that are based on a number of factors, including capitalization rates and discount rates, among others. In some circumstances, we engage independent real estate appraisal firms to provide market information and evaluations which are relevant to our purchase price allocations and determinations of depreciable useful lives; however, we are ultimately responsible for the purchase price allocations and determinations of useful lives. We allocate a portion of the purchase price to above market and below market leases based on the present value (using an interest rate which reflects the risks associated with acquired in place leases at the time each property was acquired by us) of the difference, if any, between (i) the contractual amounts to be paid pursuant to the acquired in place leases and (ii) our estimates of fair market lease rates for the corresponding leases, measured over a period equal to the terms of the respective leases. The terms of below market leases that include bargain renewal options, if any, are further adjusted if we determine that renewal is probable. We allocate a portion of the purchase price to acquired in place leases and tenant relationships based upon market estimates to lease up the property based on the leases in place at the time of purchase. In making these allocations, we consider factors such as estimated carrying costs during the expected lease up periods, including real estate taxes, insurance and other operating income and expenses and costs, such as leasing commissions, legal and other related expenses, to execute similar leases in current market conditions at the time a property was acquired by us. We allocate this aggregate value between acquired in place lease values and tenant relationships based on our evaluation of the specific characteristics of each tenant's lease. However, we have not separated the value of tenant relationships from the value of acquired in place leases because such value and related amortization expense is immaterial to our consolidated financial statements. If the value of tenant relationships becomes material in the future, we may separately allocate those amounts and amortize the allocated amount over the estimated life of the relationships. We amortize capitalized above market lease values (included in acquired real estate leases and other intangible assets, net in our consolidated balance sheets) as a reduction to rental income over the remaining non-cancelable terms of the respective leases. We amortize capitalized below market lease values (included in other liabilities in our consolidated balance sheets) as an increase to rental income over the non-cancelable periods of the respective leases. We amortize the value of in place leases exclusive of the value of above market and below market in place leases to depreciation and amortization expense over the remaining non-cancelable periods of the respective leases and during the years ended December 31, 2024, 2023 and 2022, such amortization totaled $7,367, $10,996 and $11,524, respectively. If a lease is terminated prior to its stated expiration, we fully amortize the unamortized amount relating to that lease at that time.
CASH AND CASH EQUIVALENTS	CASH AND CASH EQUIVALENTS. We consider highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents.
RESTRICTED CASH	RESTRICTED CASH. Restricted cash consists of amounts escrowed for real estate taxes, insurance and capital expenditures at certain of our mortgaged properties.
EQUITY METHOD INVESTMENTS	EQUITY METHOD INVESTMENTS. As of December 31, 2024, we owned a 10% equity interest in an unconsolidated joint venture that owns a life science property located in Boston, Massachusetts, or the Seaport JV, and a 20% equity interest in an unconsolidated joint venture for 10 medical office and life science properties, or the LSMD JV. The properties owned by the Seaport JV and LSMD JV are encumbered by an aggregate $620,000 and $456,625 of mortgage debts, respectively. We do not control the activities that are most significant to these joint ventures and, as a result, we account for our investment in these joint ventures under the equity method of accounting under the fair value option. See Notes 3 and 10 for more information regarding these joint ventures.
DEBT ISSUANCE COSTS	DEBT ISSUANCE COSTS. Debt issuance costs include issuance or assumption costs related to borrowings and we amortize those costs as interest expense over the terms of the respective loans.
DEFERRED LEASING COSTS	DEFERRED LEASING COSTS. Deferred leasing costs include capitalized brokerage costs and inducements associated with the successful negotiation of leases. We amortize deferred leasing costs, which are included in depreciation and amortization expense, and inducements, which are included as a reduction in rental income, on a straight line basis over the terms of the respective leases. Deferred leasing costs are included in other assets, net in our consolidated balance sheets.
FAIR VALUE OF FINANCIAL INSTRUMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS. We determine the estimated fair value of financial assets and liabilities using the three-tier fair value hierarchy established by accounting principles generally accepted in the United States, or GAAP, which prioritizes observable inputs in active markets when measuring fair value. The three levels of inputs that may be used to measure fair value in order of priority are as follows: Level 1—Inputs include quoted prices in active markets for identical assets or liabilities that we have the ability to access. Level 2—Inputs include quoted prices in markets that are less active or inactive or for which all significant inputs are observable, either directly or indirectly. Level 3—Inputs include unobservable prices and are supported by little or no market activity and are significant to the overall fair value measurement.
REVENUE RECOGNITION	REVENUE RECOGNITION. We are a lessor of medical office and life science properties, senior living communities and other healthcare related properties. Our leases provide our tenants with the contractual right to use and economically benefit from all of the premises demised under the leases; therefore, we have determined to evaluate our leases as lease arrangements.
PER COMMON SHARE AMOUNTS	PER COMMON SHARE AMOUNTS. We calculate basic earnings per common share by dividing net income (loss) by the weighted average number of our common shares of beneficial interest, $.01 par value, or our common shares, outstanding during the period. We calculate diluted earnings per common share using the more dilutive of the two class method or the treasury stock method. Unvested share awards and other potentially dilutive common shares, together with the related impact on earnings, are considered when calculating diluted earnings per share.
INCOME TAXES	INCOME TAXES. We have elected to be taxed as a REIT under the United States Internal Revenue Code of 1986, as amended, and, as such, are generally not subject to federal and most state income taxation on our operating income provided we distribute our taxable income to our shareholders and meet certain organization and operating requirements. We do, however, lease our managed senior living communities to our wholly owned TRSs that, unlike most of our subsidiaries, file a separate consolidated federal corporate income tax return and are subject to federal and state income taxes. Our consolidated income tax provision includes the income tax provision related to the operations of our TRSs and certain state income taxes we incur despite our taxation as a REIT. Our current income tax expense (or benefit) fluctuates from period to period based primarily on the timing of our income, including gains on the disposition of properties or losses in a particular quarter. The Income Taxes Topic of the Codification prescribes how we should recognize, measure and present in our consolidated financial statements uncertain tax positions that have been taken or are expected to be taken in a tax return. Tax benefits are recognized to the extent that it is “more likely than not” that a particular tax position will be sustained upon examination or audit. To the extent the “more likely than not” standard has been satisfied, the benefit associated with a tax position is measured as the largest amount that has a greater than 50% likelihood of being realized upon settlement. We classify interest and penalties related to uncertain tax positions, if any, in our consolidated financial statements as a component of general and administrative expense.
USE OF ESTIMATES	USE OF ESTIMATES. Preparation of these consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the amounts reported in these consolidated financial statements and related notes. The actual results could differ from these estimates. Significant estimates in the consolidated financial statements include purchase price allocations, useful lives of fixed assets and assessment of impairment of real estate and the related intangibles.
SEGMENT REPORTING	SEGMENT REPORTING. As of December 31, 2024, we operate in, and report financial information for, the following two segments: our portfolio of medical office and life science properties, or our Medical Office and Life Science Portfolio, and SHOP.
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS. On December 14, 2023, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, or ASU No. 2023-09, which requires public entities to enhance their annual income tax disclosures by requiring: (i) consistent categories and greater disaggregation of information in the rate reconciliation, and (ii) income taxes paid disaggregated by jurisdiction. ASU No. 2023-09 should be applied prospectively but entities have the option to apply it retrospectively to all prior periods presented in the consolidated financial statements. ASU No. 2023-09 is effective for annual periods beginning after December 15, 2024, with early adoption permitted. We expect to include additional disclosures in the notes to our consolidated financial statements as a result of the implementation of ASU No. 2023-09; however, these changes are not expected to have a material effect on our consolidated financial statements. In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statements Expenses, or ASU No. 2024-03, which requires public entities to disclose specific expense categories such as employee compensation, depreciation and intangible asset amortization. These details must be presented in a tabular format in the notes to consolidated financial statements for both interim and annual reporting periods. ASU 2024-03 is required to be applied prospectively but can be applied retrospectively, and is effective for the first annual reporting periods beginning after December 15, 2026, and interim reporting periods within annual reporting periods beginning after December 15, 2027, with early adoption permitted. We are currently evaluating the impact of ASU 2024-03 will have on our consolidated financial statements. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, or ASU No. 2023-07, which requires public entities, including those with a single reportable segment, to: (i) provide disclosures of significant segment expenses and other segment items if they are regularly provided to the chief operating decision maker, or the CODM, and included in each reported measure of segment profit or loss; (ii) provide all annual disclosures about a reportable segment’s profit or loss and assets currently required by ASC 280, Segment Reporting, in interim periods; and (iii) disclose the CODM’s title and position, as well as an explanation of how the CODM uses the reported measures and other disclosures. ASU No. 2023-07 does not change how a public entity identifies its operating segments, aggregates those operating segments or applies the quantitative thresholds to determine its reportable segments. We adopted the new standard effective December 31, 2024. As a result, we have included additional information related to the required disclosures in Note 11.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2024

BASIS OF PRESENTATION. Our consolidated financial statements include the accounts of Diversified Healthcare Trust, we, us or our, and our subsidiaries, all of which are 100% owned directly or indirectly by us as of December 31, 2024. All intercompany transactions and balances with or among our consolidated subsidiaries have been eliminated.

REAL ESTATE PROPERTIES

REAL ESTATE PROPERTIES. We record properties at our cost and calculate depreciation on real estate investments on a straight line basis over estimated useful lives generally up to 40 years.

We allocate the purchase prices of our properties to land, building and improvements based on determinations of the fair values of these assets assuming the properties are vacant. We determine the fair value of each property using methods similar to those used by independent appraisers, which may involve estimated cash flows that are based on a number of factors, including capitalization rates and discount rates, among others. In some circumstances, we engage independent real estate appraisal firms to provide market information and evaluations which are relevant to our purchase price allocations and determinations of depreciable useful lives; however, we are ultimately responsible for the purchase price allocations and determinations of useful lives. We allocate a portion of the purchase price to above market and below market leases based on the present value (using an interest rate which reflects the risks associated with acquired in place leases at the time each property was acquired by us) of the difference, if any, between (i) the contractual amounts to be paid pursuant to the acquired in place leases and (ii) our estimates of fair market lease rates for the corresponding leases, measured over a period equal to the terms of the respective leases. The terms of below market leases that include bargain renewal options, if any, are further adjusted if we determine that renewal is probable. We allocate a portion of the purchase price to acquired in place leases and tenant relationships based upon market estimates to lease up the property based on the leases in place at the time of purchase. In making these allocations, we consider factors such as estimated carrying costs during the expected lease up periods, including real estate taxes, insurance and other operating income and expenses and costs, such as leasing commissions, legal and other related expenses, to execute similar leases in current market conditions at the time a property was acquired by us. We allocate this aggregate value between acquired in place lease values and tenant relationships based on our evaluation of the specific characteristics of each tenant's lease. However, we have not separated the value of tenant relationships from the value of acquired in place leases because such value and related amortization expense is immaterial to our consolidated financial statements. If the value of tenant relationships becomes material in the future, we may separately allocate those amounts and amortize the allocated amount over the estimated life of the relationships.

We amortize capitalized above market lease values (included in acquired real estate leases and other intangible assets, net in our consolidated balance sheets) as a reduction to rental income over the remaining non-cancelable terms of the respective leases. We amortize capitalized below market lease values (included in other liabilities in our consolidated balance sheets) as an increase to rental income over the non-cancelable periods of the respective leases. We amortize the value of in place leases exclusive of the value of above market and below market in place leases to depreciation and amortization expense over the remaining non-cancelable periods of the respective leases and during the years ended December 31, 2024, 2023 and 2022, such amortization totaled $7,367, $10,996 and $11,524, respectively. If a lease is terminated prior to its stated expiration, we fully amortize the unamortized amount relating to that lease at that time.

CASH AND CASH EQUIVALENTS

CASH AND CASH EQUIVALENTS. We consider highly liquid investments with original maturities of three months or less at the date of purchase to be cash equivalents.

RESTRICTED CASH

RESTRICTED CASH. Restricted cash consists of amounts escrowed for real estate taxes, insurance and capital expenditures at certain of our mortgaged properties.

EQUITY METHOD INVESTMENTS

EQUITY METHOD INVESTMENTS. As of December 31, 2024, we owned a 10% equity interest in an unconsolidated joint venture that owns a life science property located in Boston, Massachusetts, or the Seaport JV, and a 20% equity interest in an unconsolidated joint venture for 10 medical office and life science properties, or the LSMD JV. The properties owned by the Seaport JV and LSMD JV are encumbered by an aggregate $620,000 and $456,625 of mortgage debts, respectively. We do not control the activities that are most significant to these joint ventures and, as a result, we account for our investment in these joint ventures under the equity method of accounting under the fair value option. See Notes 3 and 10 for more information regarding these joint ventures.

DEBT ISSUANCE COSTS

DEBT ISSUANCE COSTS. Debt issuance costs include issuance or assumption costs related to borrowings and we amortize those costs as interest expense over the terms of the respective loans.

DEFERRED LEASING COSTS

DEFERRED LEASING COSTS. Deferred leasing costs include capitalized brokerage costs and inducements associated with the successful negotiation of leases. We amortize deferred leasing costs, which are included in depreciation and amortization expense, and inducements, which are included as a reduction in rental income, on a straight line basis over the terms of the respective leases. Deferred leasing costs are included in other assets, net in our consolidated balance sheets.

FAIR VALUE OF FINANCIAL INSTRUMENTS

FAIR VALUE OF FINANCIAL INSTRUMENTS. We determine the estimated fair value of financial assets and liabilities using the three-tier fair value hierarchy established by accounting principles generally accepted in the United States, or GAAP, which prioritizes observable inputs in active markets when measuring fair value. The three levels of inputs that may be used to measure fair value in order of priority are as follows:

Level 1—Inputs include quoted prices in active markets for identical assets or liabilities that we have the ability to access.

Level 2—Inputs include quoted prices in markets that are less active or inactive or for which all significant inputs are observable, either directly or indirectly.

Level 3—Inputs include unobservable prices and are supported by little or no market activity and are significant to the overall fair value measurement.

REVENUE RECOGNITION

REVENUE RECOGNITION. We are a lessor of medical office and life science properties, senior living communities and other healthcare related properties. Our leases provide our tenants with the contractual right to use and economically benefit from all of the premises demised under the leases; therefore, we have determined to evaluate our leases as lease arrangements.

PER COMMON SHARE AMOUNTS

PER COMMON SHARE AMOUNTS. We calculate basic earnings per common share by dividing net income (loss) by the weighted average number of our common shares of beneficial interest, $.01 par value, or our common shares, outstanding during the period. We calculate diluted earnings per common share using the more dilutive of the two class method or the treasury stock method. Unvested share awards and other potentially dilutive common shares, together with the related impact on earnings, are considered when calculating diluted earnings per share.

INCOME TAXES

INCOME TAXES. We have elected to be taxed as a REIT under the United States Internal Revenue Code of 1986, as amended, and, as such, are generally not subject to federal and most state income taxation on our operating income provided we distribute our taxable income to our shareholders and meet certain organization and operating requirements. We do, however, lease our managed senior living communities to our wholly owned TRSs that, unlike most of our subsidiaries, file a separate consolidated federal corporate income tax return and are subject to federal and state income taxes. Our consolidated income tax provision includes the income tax provision related to the operations of our TRSs and certain state income taxes we incur despite our taxation as a REIT. Our current income tax expense (or benefit) fluctuates from period to period based primarily on the timing of our income, including gains on the disposition of properties or losses in a particular quarter.

The Income Taxes Topic of the Codification prescribes how we should recognize, measure and present in our consolidated financial statements uncertain tax positions that have been taken or are expected to be taken in a tax return. Tax benefits are recognized to the extent that it is “more likely than not” that a particular tax position will be sustained upon examination or audit. To the extent the “more likely than not” standard has been satisfied, the benefit associated with a tax position is measured as the largest amount that has a greater than 50% likelihood of being realized upon settlement. We classify interest and penalties related to uncertain tax positions, if any, in our consolidated financial statements as a component of general and administrative expense.

USE OF ESTIMATES

USE OF ESTIMATES. Preparation of these consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the amounts reported in these consolidated financial statements and related notes. The actual results could differ from these estimates. Significant estimates in the consolidated financial statements include purchase price allocations, useful lives of fixed assets and assessment of impairment of real estate and the related intangibles.

SEGMENT REPORTING

SEGMENT REPORTING. As of December 31, 2024, we operate in, and report financial information for, the following two segments: our portfolio of medical office and life science properties, or our Medical Office and Life Science Portfolio, and SHOP.

RECENT ACCOUNTING PRONOUNCEMENTS

RECENT ACCOUNTING PRONOUNCEMENTS.

On December 14, 2023, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, or ASU No. 2023-09, which requires public entities to enhance their annual income tax disclosures by requiring: (i) consistent categories and greater disaggregation of information in the rate reconciliation, and (ii) income taxes paid disaggregated by jurisdiction. ASU No. 2023-09 should be applied prospectively but entities have the option to apply it retrospectively to all prior periods presented in the consolidated financial statements. ASU No. 2023-09 is effective for annual periods beginning after December 15, 2024, with early adoption permitted. We expect to include additional disclosures in the notes to our consolidated financial statements as a result of the implementation of ASU No. 2023-09; however, these changes are not expected to have a material effect on our consolidated financial statements.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statements Expenses, or ASU No. 2024-03, which requires public entities to disclose specific expense categories such as employee compensation, depreciation and intangible asset amortization. These details must be presented in a tabular format in the notes to consolidated financial statements for both interim and annual reporting periods. ASU 2024-03 is required to be applied prospectively but can be applied retrospectively, and is effective for the first annual reporting periods beginning after December 15, 2026, and interim reporting periods within annual reporting periods beginning after December 15, 2027, with early adoption permitted. We are currently evaluating the impact of ASU 2024-03 will have on our consolidated financial statements.

In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, or ASU No. 2023-07, which requires public entities, including those with a single reportable segment, to: (i) provide disclosures of significant segment expenses and other segment items if they are regularly provided to the chief operating decision maker, or the CODM, and included in each reported measure of segment profit or loss; (ii) provide all annual disclosures about a reportable segment’s profit or loss and assets currently required by ASC 280, Segment Reporting, in interim periods; and (iii) disclose the CODM’s title and position, as well as an explanation of how the CODM uses the reported measures and other disclosures. ASU No. 2023-07 does not change how a public entity identifies its operating segments, aggregates those operating segments or applies the quantitative thresholds to determine its reportable segments. We adopted the new standard effective December 31, 2024. As a result, we have included additional information related to the required disclosures in Note 11.