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(Common Units) (Narrative) (Details) $ / shares in Units, $ in Thousands |  | 6 Months Ended |  |
--- | --- | --- | --- | ---
Feb. 09, 2019 USD ($) shares | Jun. 30, 2019 USD ($) shares yr | Jun. 28, 2019 $ / shares | Dec. 31, 2018 USD ($)
OP Units [Member] |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |
OP Units for redemption (in shares) |  | 34,967 |  |
Redemption of OP units issued on conversion of LTIP Units (in shares) |  | 33,767 |  |
Restriction on redemption of OP Unit to Common Stock (in years) | yr |  | 1 |  |
Redemption of OP Unit equivalent to Common Stock (in shares) |  | 1 |  |
Common units of operating partnership if converted value | $ |  | $ 2,300,000 |  |
Closing price of common stock (in dollars per share) | $ / shares |  |  | $ 129.00 |
2016 MYLTIP [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 |  |  |
2016 MYLTIP Units Forfeited | 364,980 |  |  |
Boston Properties Limited Partnership |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |
Common units of operating partnership if converted value | $ |  | $ 2,324,238 |  | $ 2,000,591
Boston Properties Limited Partnership | OP Units [Member] |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |
MYLTIP distribution prior to measurement date |  | 10.00% |  |
Boston Properties Limited Partnership | 2017 MYLTIP [Member] |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |
2017 MYLTIP (in units) |  | 394,921 |  |
Boston Properties Limited Partnership | 2018 MYLTIP [Member] |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |
2018 MYLTIP |  | 336,195 |  |
Boston Properties Limited Partnership | 2019 MYLTIP [Member] |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |
2019 MYLTIPS |  | 220,734 |  |

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