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Unsecured Senior Notes Unsecured Senior Notes (Narrative) (Details) - USD ($) $ in Thousands				12 Months Ended
	Sep. 18, 2019	Sep. 03, 2019	Jun. 21, 2019	Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Proceeds from unsecured senior notes				$ 1,548,106		$ 996,410	$ 847,935
Redemption of unsecured senior notes				699,237		699,517	848,020
Losses (gains) from early extinguishments of debt				29,540		16,490	(496)
Boston Properties Limited Partnership
Debt Instrument [Line Items]
Proceeds from unsecured senior notes				1,548,106		996,410	847,935
Redemption of unsecured senior notes				699,237		699,517	848,020
Losses (gains) from early extinguishments of debt				29,540		$ 16,490	$ (496)
Boston Properties Limited Partnership | Senior Notes [Member]
Debt Instrument [Line Items]
Principal Amount				$ 8,450,000
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 December 31, 2019, Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements.
Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 3.505%
Debt Instrument [Line Items]
Principal Amount			$ 850,000	$ 850,000
Coupon/Stated Rate			3.40%	3.40%
Senior Notes Pricing			99.815%
Effective Rate			3.505%	3.505%	[1]
Proceeds from unsecured senior notes			$ 841,400
Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 2.984%
Debt Instrument [Line Items]
Principal Amount		$ 700,000		$ 700,000
Coupon/Stated Rate		2.90%		2.90%
Senior Notes Pricing		99.954%
Effective Rate		2.984%		2.984%	[1]
Proceeds from unsecured senior notes		$ 693,800
Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 5.708%
Debt Instrument [Line Items]
Coupon/Stated Rate	5.625%
Debt Instrument, Face Amount	$ 700,000
Redemption of unsecured senior notes	740,700
Accrued and Unpaid Interest	$ 13,500
Redemption Price, Percentage	103.90%
Losses (gains) from early extinguishments of debt	$ 28,000
Redemption Premium	$ 27,300
[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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