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Stock Option and Incentive Plan (Narrative) (Details) - USD ($) $ in Millions | Feb. 06, 2020 | Feb. 04, 2020 | Feb. 05, 2019
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MYLTIP 2019 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  |  | 4 years
MYLTIP 2020 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
TSR measurement (in years) |  | three-year |
Minimum earned awards |  | 0 |
Maximum Earned Awards |  | 203,278 |
Earned wards - Target |  | 101,638 |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights |  | Earned awards (if any) will vest 50% on February 3, 2023 and 50% on February 3, 2024, 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 3, 2023, earned awards will be calculated based on TSR performance up to the date of the change of control. The 2020 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. |
Value of MYLTIP Awards |  | $ 13.7 |
MYLTIP 2017 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Value of MYLTIP Awards | $ 17.6 |  |
Final awards percentage of target | 83.80% |  |
MYLTIP Units forfeited | 270,942 |  |

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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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