Stock Option and Incentive Plan Stock Option and Incentive Plan (Narrative) (Details) - USD ($) $ in Millions	Feb. 09, 2019	Feb. 05, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights		Earned awards (if any) will vest 50% on February 4, 2022 and 50% on February 4, 2023, based on continued employment. Vesting will be accelerated in the event of a change in control, termination of employment by Boston Properties, Inc. without cause, or termination of employment by the award recipient for good reason, death, disability or retirement. If there is a change of control prior to February 4, 2022, earned awards will be calculated based on TSR performance up to the date of the change of control. The 2019 MYLTIP awards are in the form of LTIP Units issued on the grant date which (i) are subject to forfeiture to the extent awards are not earned and (ii) prior to the performance measurement date are only entitled to one-tenth (10%) of the regular quarterly distributions payable on common partnership units.
2019 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
TSR Measurement, Years		three year
Minimum earned awards		0
Maximum Earned Awards		220,734
Target Tier		110,367
Value of MYLTIP Awards		$ 13.5
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
2016 MYLTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards	$ 13.6
Final awards percentage of target	69.50%
2016 MYLTIP Units Forfeited	364,980