Number Of Non Employee Directors Electing To Receive Deferred Stock Units

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Separate Unrestricted Cash For Deferred Compensation Plan.

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Sum of the carrying values as of the balance sheet date of obligations incurred through that date, including liabilities incurred and payable to vendors for goods and services received, taxes, interest, rent and utilities, compensation costs, payroll taxes and fringe benefits (other than pension and postretirement obligations), contractual rights and obligations, and statutory obligations.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Decrease for amounts of indebtedness forgiven by the holder of the debt instrument.

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

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Weighted average interest rate of debt outstanding.

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

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The amount of interest income and other income recognized during the period. Included in this element is interest derived from investments in debt securities, cash and cash equivalents, and other investments which reflect the time value of money or transactions in which the payments are for the use or forbearance of money and other income from ancillary business-related activities (that is, excluding major activities considered part of the normal operations of the business).

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Net rentable area for properties owned.

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Amortized cost, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement and net investment in lease.

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Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Excludes Selling, General and Administrative Expense.

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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.

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Amount of a new issue of securities classified as temporary equity that are allocated to investors for them to buy. When securities are sold on a subscription basis, the issuer does not initially receive the total proceeds. In general, the issuer does not issue the securities to the investor until it receives the entire proceeds. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

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Related Party Transactions (Details) $ in Thousands			12 Months Ended
Related Party Transactions (Details) $ in Thousands	Oct. 17, 2025 USD ($)	Oct. 16, 2025 USD ($)	Dec. 31, 2025 USD ($) ft² nonemployeedirectors shares	Dec. 31, 2024 USD ($) shares	Dec. 31, 2023 USD ($)	Jun. 05, 2023 USD ($) ft²
Related Party Transaction [Line Items]
Interest and Other Income			$ 35,784	$ 60,199	$ 69,964
Number Of Non Employee Directors Electing To Receive Deferred Stock Units \| nonemployeedirectors			7
Separate Unrestricted Cash For Deferred Compensation Plan.			$ 44,400	39,400
Liability for directors			$ 480,017	$ 401,874
Reedemable deferred stock units, units \| shares			111,701	128,227
500 North Capitol Street, NW \| Unconsolidated Properties
Related Party Transaction [Line Items]
Net Rentable Area (in sf) \| ft²						231,000
3 Hudson Boulevard [Member] \| Unconsolidated Properties
Related Party Transaction [Line Items]
Debt Instrument, Basis Spread on Variable Rate		3.61%
Boston Properties Limited Partnership
Related Party Transaction [Line Items]
Debt			$ 9,850,000
Interest and Other Income			35,784	$ 60,199	69,964
Liability for directors			$ 480,017	$ 401,874
Reedemable deferred stock units, units \| shares			111,701	128,227
3 Hudson Boulevard [Member]
Related Party Transaction [Line Items]
Ownership Percentage			25.00%
Net Rentable Area (in sf) \| ft²			2,000,000.0
500 North Capitol Venture LLC [Member]
Related Party Transaction [Line Items]
Ownership Percentage			30.00%
500 North Capitol Venture LLC [Member] \| 500 North Capitol Street, NW \| Unconsolidated Properties
Related Party Transaction [Line Items]
Ownership Percentage						30.00%
Related Party \| 3 Hudson Boulevard [Member] \| Unconsolidated Properties \| Notes Receivables [Member]
Related Party Transaction [Line Items]
Related party note receivable, net		$ 80,000
Debt Instrument, Basis Spread on Variable Rate	7.25%	3.61%
Real Estate Brokerage Firm \| Related Party
Related Party Transaction [Line Items]
Operating Costs and Expenses					500
Related Party
Related Party Transaction [Line Items]
Related party note receivable, net			$ 28,346	$ 88,779
Separate Unrestricted Cash For Deferred Compensation Plan.			800	700
Liability for directors			800	700
Related Party \| 500 North Capitol Street, NW \| Unconsolidated Properties
Related Party Transaction [Line Items]
Debt						$ 105,000
Debt, Weighted Average Interest Rate						6.83%
Related Party \| 500 North Capitol Street, NW \| Unconsolidated Properties \| Notes Receivables [Member]
Related Party Transaction [Line Items]
Related party note receivable, net						$ 10,500
Debt Instrument, Interest Rate, Stated Percentage						8.03%
Interest and Other Income			900	800	600
Related Party \| 3 Hudson Boulevard [Member]
Related Party Transaction [Line Items]
Debt Instrument, Decrease, Forgiveness	$ 5,800
Related Party \| 3 Hudson Boulevard [Member] \| Unconsolidated Properties
Related Party Transaction [Line Items]
Debt			18,400
Related Party \| 3 Hudson Boulevard [Member] \| Unconsolidated Properties \| Maximum [Member]
Related Party Transaction [Line Items]
Debt	$ 50,000
Related Party \| Boston Properties Limited Partnership
Related Party Transaction [Line Items]
Related party note receivable, net			28,346	88,779
Related Party \| 3 Hudson Boulevard [Member]
Related Party Transaction [Line Items]
Interest and Other Income			$ 6,400	$ 11,600	$ 8,900