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Unsecured Senior Notes (Narrative) (Details) - USD ($) $ in Thousands		9 Months Ended
	Jan. 15, 2025	Sep. 30, 2025	Sep. 30, 2024	Aug. 26, 2024
Debt Instrument [Line Items]
Repayments of Unsecured Debt		$ 850,000	$ 700,000
Proceeds from unsecured senior notes		0	849,671
Boston Properties Limited Partnership
Debt Instrument [Line Items]
Repayments of Unsecured Debt		850,000	700,000
Proceeds from unsecured senior notes		$ 0	$ 849,671
3.350% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership
Debt Instrument [Line Items]
Debt	$ 850,000
Debt Instrument, Interest Rate, Stated Percentage	3.20%
Repayments of Unsecured Debt	$ 863,600
Debt Instrument, Increase, Accrued Interest	$ 13,600
5.842% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				5.75%

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