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Unsecured Senior Notes (Narrative) (Details) - USD ($) $ in Thousands				3 Months Ended			9 Months Ended
	Sep. 29, 2021	Mar. 16, 2021	Feb. 14, 2021	Sep. 30, 2021		Sep. 30, 2020	Sep. 30, 2021		Sep. 30, 2020
Debt Instrument [Line Items]
Repayments of Unsecured Debt							$ 843,710		$ 0
Loss from early extinguishment of debt				$ 0		$ 0	898		0
Proceeds from unsecured senior notes							1,695,996		1,248,125
Boston Properties Limited Partnership
Debt Instrument [Line Items]
Repayments of Unsecured Debt							843,710		0
Loss from early extinguishment of debt				0		$ 0	898		0
Proceeds from unsecured senior notes							$ 1,695,996		$ 1,248,125
Debt Instrument, Covenant Description							The indenture relating to the unsecured senior notes contains certain financial restrictions and requirements, including (1) a leverage ratio not to exceed 60%, (2) a secured debt leverage ratio not to exceed 50%, (3) an interest coverage ratio of greater than 1.50, and (4) an unencumbered asset value of not less than 150% of unsecured debt.
Debt Instrument, Covenant Compliance							At September 30, 2021, Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements.
Senior Notes | Boston Properties Limited Partnership
Debt Instrument [Line Items]
Debt				10,550,000			$ 10,550,000
2.671% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership
Debt Instrument [Line Items]
Debt		$ 850,000		$ 850,000			$ 850,000
Debt Instrument, Interest Rate, Stated Percentage		2.55%		2.55%			2.55%
Senior Notes Pricing		99.57%
Debt Instrument, Interest Rate, Effective Percentage		2.671%		2.671%	[1]		2.671%	[1]
Proceeds from unsecured senior notes		$ 839,200
4.289% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership
Debt Instrument [Line Items]
Debt			$ 850,000
Debt Instrument, Interest Rate, Stated Percentage			4.125%
Repayments of Unsecured Debt			$ 858,700
Debt Instrument, Increase, Accrued Interest			8,700
Loss from early extinguishment of debt			$ 400
2.524% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership
Debt Instrument [Line Items]
Debt	$ 850,000			$ 850,000			$ 850,000
Debt Instrument, Interest Rate, Stated Percentage	2.45%			2.45%			2.45%
Senior Notes Pricing	99.959%
Debt Instrument, Interest Rate, Effective Percentage	2.524%			2.524%	[1]		2.524%	[1]
Proceeds from unsecured senior notes	$ 842,500
[1] Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.

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