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Derivative Instruments and Hedging Activities Derivative Instrument and Hedging Activities Notional Table (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016 | Dec. 31, 2016 | Dec. 31, 2015
Derivative [Line Items] |  |  |  |  |  |
Fair Value | $ 0 | $ 5,712 | $ (6,133) | $ (85,285) |  |
Boston Properties Limited Partnership | Interest Rate Swap [Member] |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Notional Amount |  |  |  |  |  | $ 550,000
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative Liability, Notional Amount |  |  |  |  | $ 350,000 |
Derivative Asset, Notional Amount |  |  |  |  | 100,000 |
Notional Amount |  | $ 450,000 |  | $ 450,000 | 450,000 |
Fair Value |  |  |  |  | (8,264) |
Liability [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Fair Value |  |  |  |  | $ (8,773) |
Liability [Member] | Minimum [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  |  | 2.418% |
Liability [Member] | Maximum [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  |  | 2.95% |
Assets [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Fair Value |  |  |  |  | $ 509 |
Assets [Member] | Minimum [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  |  | 2.336% |
Assets [Member] | Maximum [Member] | 767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |  |  |  |
Derivative [Line Items] |  |  |  |  |  |
Derivative, Fixed Interest Rate |  |  |  |  | 2.388% |

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References 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 + Details
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