Noncontrolling Interests (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest in Limited Partnerships	$ 1,725,600	$ 1,726,933
Boston Properties Limited Partnership | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	16,053,640
Boston Properties Limited Partnership | LTIP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	1,525,306
Boston Properties Limited Partnership | 2012 OPP and 2013-2018 MYLTIP
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	451,043
Boston Properties Limited Partnership | MYLTIP 2019 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	219,916
Boston Properties Limited Partnership | MYLTIP 2020 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	203,278
Boston Properties Limited Partnership | MYLTIP 2021
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	352,021