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(Common Units) (Narrative) (Details) $ / shares in Units, $ in Millions |  | 9 Months Ended
--- | --- | ---
Feb. 03, 2017 USD ($) shares | Sep. 30, 2017 USD ($) yr $ / shares shares
OP Units [Member] |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |
OP Units for redemption (in shares) |  | 492,617
Redemption of OP units issued on conversion of LTIP Units (in shares) |  | 33,466
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 | $ |  | $ 2,200.0
Closing price of common stock (in dollars per share) | $ / shares |  | $ 122.88
MYLTIP 2014 [Member] |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |
Final awards percentage of target | 27.70% |
Value of MYLTIP Awards | $ | $ 3.5 |
2014 MYLTIP Units Forfeited | 447,386 |
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 | MYLTIP 2014 [Member] |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |
2014 MYLTIP (in units) |  | 25,107
Boston Properties Limited Partnership | 2015 MYLTIP [Member] |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |
2015 MYLTIPS (in units) |  | 366,618
Boston Properties Limited Partnership | 2016 MYLTIP [Member] |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |
2016 MYLTIPs (in units) |  | 473,360
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) |  | 400,000

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