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Derivative Instruments and Hedging Activities (Details) $ in Thousands |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Apr. 24, 2017 USD ($) | Aug. 17, 2016 USD ($) yr | Sep. 30, 2017 USD ($) | Sep. 30, 2016 USD ($) | Sep. 30, 2017 USD ($) | Sep. 30, 2016 USD ($) swaps yr | Dec. 31, 2015 USD ($) swaps | Dec. 31, 2016 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Mortgage notes payable, net |  |  | $ 2,982,067 |  | $ 2,982,067 |  |  | $ 2,063,087
Cash payment to settle interest rate swap contracts |  |  |  |  | (65,031) | $ (114,321) |  |
Losses from interest rate contracts |  |  | $ 0 | $ 140 | $ 0 | $ 140 |  |
Boston Properties Limited Partnership | Interest Rate Swap [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Number of interest rate swap agreements entered into (swap contracts) | swaps |  |  |  |  |  |  | 17 |
Term of anticipated mortgage loan (in years) | yr |  | 10 |  |  |  |  |  |
Average Fixed Interest Rate |  |  |  |  |  |  | 2.423% |
Notional Amount |  |  |  |  |  |  | $ 550,000 |
Cash payment to settle interest rate swap contracts |  | $ 49,300 |  |  |  |  |  |
Losses from interest rate contracts |  | 100 |  |  |  |  |  |
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion |  | 49,200 |  |  |  |  |  |
Derivative Instruments Loss Reclassified From Accumulated OCI Into Income Effective yearly amount |  | $ 4,900 |  |  |  |  |  |
767 Fifth Partners LLC [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Ownership Percentage by the Company |  |  | 60.00% |  | 60.00% |  |  |
767 Fifth Partners LLC [Member] | Interest Rate Swap [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Number of interest rate swap agreements entered into (swap contracts) | swaps |  |  |  |  |  | 16 |  |
Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years) | yr |  |  |  |  |  | 10 |  |
Average Fixed Interest Rate |  |  |  | 2.619% |  | 2.619% |  |
Notional Amount |  |  |  | $ 450,000 |  | $ 450,000 |  | 450,000
Cash payment to settle interest rate swap contracts | $ 14,400 |  |  |  |  |  |  |
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion | 14,400 |  |  |  |  |  |  |
Derivative Instruments Loss Reclassified From Accumulated OCI Into Income Effective yearly amount | 1,400 |  |  |  |  |  |  |
Unsecured Debt [Member] | Boston Properties Limited Partnership |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Coupon/Stated Rate |  | 2.75% |  |  |  |  |  |
Boston Properties Limited Partnership |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Mortgage notes payable, net |  |  | $ 2,982,067 |  | $ 2,982,067 |  |  | $ 2,063,087
Cash payment to settle interest rate swap contracts |  |  |  |  | (65,031) | (114,321) |  |
Losses from interest rate contracts |  |  | $ 0 | $ 140 | $ 0 | $ 140 |  |
767 Fifth Avenue (the General Motors Building) | Secured Debt [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Mortgage notes payable, net | $ 2,300,000 |  |  |  |  |  |  |
Coupon/Stated Rate | 3.43% |  |  |  |  |  |  |

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