Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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- Definition

Nominal or face amount used to calculate payments on the derivative asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
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High end of the range of fixed interest rates when a range is presented for a group of interest rate derivatives.

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No definition available.

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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References

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-Publisher FASB
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- Definition

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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Low end of the range of fixed interest rates when a range is presented for a group of interest rate derivatives.

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- Definition

Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Derivative Instruments and Hedging Activities Derivative Instrument and Hedging Activities Notional Table (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Derivative [Line Items]
Fair Value	$ (32,351)	$ 15,639	$ (90,997)	$ 12,106
Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	1,000,000		1,000,000		$ 950,000
Fair Value			(101,299)		(10,302)
Boston Properties Limited Partnership \| Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	550,000		550,000		550,000
Fair Value			(36,561)		(4,231)
Boston Properties Limited Partnership \| Interest Rate Swap [Member] \| Interest Rate Swap Range 2.129% - 2.571% [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	$ 550,000		$ 550,000
Derivative, Lower Fixed Interest Rate Range	2.129%		2.129%
Derivative, Higher Fixed Interest Rate Range	2.571%		2.571%
Fair Value			$ (53,861)
Boston Properties Limited Partnership \| Interest Rate Swap [Member] \| Interest Rate Swap Range 2.348% - 2.571% [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount					$ 400,000
Derivative, Lower Fixed Interest Rate Range					2.348%
Derivative, Higher Fixed Interest Rate Range					2.571%
Fair Value					$ (5,419)
Boston Properties Limited Partnership \| Interest Rate Swap [Member] \| Interest Rate Swap Range 2.129% - 2.325% [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount					$ 150,000
Derivative, Lower Fixed Interest Rate Range					2.129%
Derivative, Higher Fixed Interest Rate Range					2.325%
Fair Value					$ 1,188
767 Fifth Partners LLC [Member] \| Interest Rate Swap [Member]
Derivative [Line Items]
Notional Amount	$ 450,000		450,000		400,000
Fair Value			(32,387)		(6,071)
767 Fifth Partners LLC [Member] \| Interest Rate Swap [Member] \| Interest Rate Swap Range 2.336% - 2.950% [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	$ 450,000		$ 450,000
Derivative, Lower Fixed Interest Rate Range	2.336%		2.336%
Derivative, Higher Fixed Interest Rate Range	2.95%		2.95%
Fair Value			$ (47,438)
767 Fifth Partners LLC [Member] \| Interest Rate Swap [Member] \| Interest Rate Swap Range 2.677% - 2.950% [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount					$ 250,000
Derivative, Lower Fixed Interest Rate Range					2.677%
Derivative, Higher Fixed Interest Rate Range					2.95%
Fair Value					$ (7,247)
767 Fifth Partners LLC [Member] \| Interest Rate Swap [Member] \| Interest Rate Swap Range 2.336% - 2.430% [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount					$ 150,000
Derivative, Lower Fixed Interest Rate Range					2.336%
Derivative, Higher Fixed Interest Rate Range					2.43%
Fair Value					$ 1,176