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Mortgage Notes Payable, Net (Details) $ in Thousands |  |  |  |  | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | ---
Dec. 31, 2021 USD ($) Rate | Dec. 14, 2021 USD ($) loanExtension yr Rate shares | Dec. 10, 2021 USD ($) Rate | Mar. 26, 2021 USD ($) Rate | Dec. 31, 2021 USD ($) Rate | Dec. 31, 2020 USD ($) Rate | Dec. 31, 2019 USD ($) | Dec. 15, 2021 | Dec. 09, 2021 USD ($) Rate
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Mortgage notes payable, net | $ 3,267,914 |  |  |  | $ 3,267,914 | $ 2,909,081 |  |  |
Debt Instrument, Collateral |  |  |  |  | each collateralized by one or more buildings and related land included in real estate assets | each collateralized by one or more buildings and related land included in real estate assets |  |  |
Number Of Variable Mortgage Loans | 0 |  |  |  | 0 | 0 |  |  |
Repayments of Secured Debt |  |  |  |  | $ 832,296 | $ 17,168 | $ 46,173 |  |
Loss from early extinguishment of debt |  |  |  |  | 45,182 | 0 | 29,540 |  |
Assumption of mortgage notes payable |  |  |  |  | 200,311 | 0 | 0 |  |
Debt Instrument, Basis Spread on Variable Rate | 0.775% |  |  |  |  |  |  |  |
Boston Properties Limited Partnership |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Mortgage notes payable, net | $ 3,267,914 |  |  |  | 3,267,914 | 2,909,081 |  |  |
Repayments of Secured Debt |  |  |  |  | 832,296 | 17,168 | 46,173 |  |
Loss from early extinguishment of debt |  |  |  |  | 45,182 | 0 | 29,540 |  |
Assumption of mortgage notes payable |  |  |  |  | 200,311 | 0 | $ 0 |  |
601 Lexington Avenue |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Noncontrolling Interest, Ownership Percentage by Parent |  |  | 55.00% |  |  |  |  |  |
Loss from early extinguishment of debt |  |  | $ 100 |  |  |  |  |  |
360 Park South Avenue |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Debt - Total loan amount |  | $ 220,000 |  |  |  |  |  |  |
Noncash or Part Noncash Acquisition, Value of Assets Acquired |  | 300,700 |  |  |  |  |  |  |
Assumption of mortgage notes payable |  | $ 200,300 |  |  |  |  |  |  |
number of investors |  |  |  |  |  |  |  | 2 |
Ownership Percentage |  |  |  |  |  |  |  | 42.21% |
360 Park South Avenue | Boston Properties Limited Partnership |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued | shares |  | 866,503 |  |  |  |  |  |  |
Fixed Rate Mortgage [Member] |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Mortgage notes payable, net | $ 3,300,000 |  |  |  | $ 3,300,000 | $ 2,900,000 |  |  |
Debt, Weighted Average Interest Rate | Rate | 3.24% |  |  |  | 3.24% | 3.72% |  |  |
Fixed Rate Mortgage [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | Rate | 2.79% |  |  |  | 2.79% | 3.43% |  |  |
Fixed Rate Mortgage [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | Rate | 3.43% |  |  |  | 3.43% | 6.94% |  |  |
Fixed Rate Mortgage [Member] | University Place |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | Rate |  |  |  | 6.94% |  |  |  |  |
Repayments of Secured Debt |  |  |  | $ 900 |  |  |  |  |
Fixed Rate Mortgage [Member] | 601 Lexington Avenue |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Mortgage notes payable, net |  |  | $ 1,000,000 |  |  |  |  |  | $ 616,100
Debt Instrument, Interest Rate, Stated Percentage | Rate |  |  | 2.79% |  |  |  |  |  | 4.75%
Fixed Rate Mortgage [Member] | 360 Park South Avenue |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | Rate |  | 6.044% |  |  |  |  |  |  |
Repayments of Secured Debt |  | $ 200,300 |  |  |  |  |  |  |
Adjustable Rate Loans | 360 Park South Avenue |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |
Debt - Total loan amount |  | 220,000 |  |  |  |  |  |  |
Proceeds from Issuance of Debt |  | $ 202,000 |  |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | Rate |  | 2.40% |  |  |  |  |  |  |
Number of extensions | loanExtension |  | 2 |  |  |  |  |  |  |
Extension Option (in years) | yr |  | 1 |  |  |  |  |  |  |

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