(Common Units) (Narrative) (Details) $ / shares in Units, $ in Thousands				12 Months Ended
	Feb. 09, 2019 USD ($) shares	Feb. 04, 2018 USD ($) shares	Feb. 03, 2017 USD ($) shares	Dec. 31, 2019 USD ($) shares yr $ / shares	Dec. 31, 2018 USD ($) 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)				144,481	83,136
Redemption of OP units issued on conversion of LTIP, OPP and MYLTIP units (in shares)				92,678	48,389
MYLTIP Units distribution as percentage of OP Unit distribution prior to measurement date				10.00%
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 | $				$ 2,500,000
Closing price of common stock (in dollars per share) | $ / shares				$ 137.86
MYLTIP 2014
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 | $			$ 3,500
MYLTIP Units forfeited			447,386
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
MYLTIP Units forfeited		337,847
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
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 | $				$ 2,468,753	$ 2,000,591
Boston Properties Limited Partnership | MYLTIP 2017 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2017 MYLTIP				394,921
Boston Properties Limited Partnership | MYLTIP 2018
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2018 MYLTIP				336,195
Boston Properties Limited Partnership | MYLTIP 2019 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2019 MYLTIPS				220,734