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(Common Units) (Narrative) (Details) $ / shares in Units, $ in Thousands |  |  |  |  | 12 Months Ended
--- | --- | --- | --- | --- | ---
Feb. 06, 2020 USD ($) shares | Sep. 03, 2019 shares | Feb. 09, 2019 USD ($) shares | Feb. 04, 2018 USD ($) shares | Dec. 31, 2020 USD ($) yr $ / shares shares | Dec. 31, 2019 USD ($) shares
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
OP Units for redemption (in shares) |  | 4,917 |  |  |  |
Boston Properties Limited Partnership |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount | $ |  |  |  |  | $ 1,643,024 | $ 2,468,753
Unvested MYLTIP Units [Member] |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
unvested MYLTIP distributions as compared to total distributions (percentage) |  |  |  |  | 10.00% |
MYLTIP 2017 [Member] |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
Final awards percentage of target | 83.80% |  |  |  |  |
Value of MYLTIP Awards | $ | $ 17,600 |  |  |  |  |
Forfeitures, in units | 270,942 |  |  |  |  |
MYLTIP 2017 [Member] | Boston Properties Limited Partnership |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
Noncontrolling Interest, Outstanding |  |  |  |  | 116,078 |
MYLTIP 2016 [Member] |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
Final awards percentage of target |  |  | 69.50% |  |  |
Value of MYLTIP Awards | $ |  |  | $ 13,600 |  |  |
Forfeitures, in units |  |  | 364,980 |  |  |
MYLTIP 2016 [Member] | Boston Properties Limited Partnership |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
Noncontrolling Interest, Outstanding |  |  |  |  | 89,791 |
MYLTIP 2015 [Member] |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
Final awards percentage of target |  |  |  | 22.00% |  |
Value of MYLTIP Awards | $ |  |  |  | $ 3,600 |  |
Forfeitures, in units |  |  |  | 337,847 |  |
MYLTIP 2015 [Member] | Boston Properties Limited Partnership |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
Noncontrolling Interest, Outstanding |  |  |  |  | 24,966 |
OP Units [Member] |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
OP Units for redemption (in shares) |  |  |  |  | 856,811 | 144,481
Restriction on redemption of OP Unit to Common Stock (in years) | yr |  |  |  |  | 1 |
Redemption of OP Unit equivalent to Common Stock (in shares) |  |  |  |  | 1 |
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount | $ |  |  |  |  | $ 1,600,000 |
Closing price of common stock (in dollars per share) | $ / shares |  |  |  |  | $ 94.53 |
Vested 2012 OPP units and MYLTIPS |  |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |
OP Units for redemption (in shares) |  |  |  |  | 88,168 | 92,678

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