Subsequent Events	12 Months Ended
Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	20. Subsequent Events On January 9, 2018, the Company completed the sale of its 500 E Street, S.W. property located in Washington, DC for a net contract sale price of approximately $118.6 million, which exceeds its carrying value. 500 E Street, S.W. is an approximately 262,000 net rentable square foot Class A office property. On January 24, 2018, the Company entered into a lease agreement with a tenant for a build-to-suit project with approximately 276,000 net rentable square feet of Class A office space at the Company's 17Fifty Presidents Street development project located in Reston, Virginia. The Company expects that the building will be complete and available for occupancy during the first quarter of 2020. On January 31, 2018, the Company partially placed in-service its Signature at Reston development project comprised of 508 apartment units and retail space aggregating approximately 515,000 square feet located in Reston, Virginia. On February 2, 2018 and February 6, 2018, Boston Properties, Inc. issued an aggregate of 18,226 shares of restricted common stock and Boston Properties Limited Partnership issued an aggregate of 195,546 LTIP units under the 2012 Plan to certain employees of Boston Properties, Inc. On February 4, 2018, the measurement period for the Company’s 2015 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 22.0% of target or an aggregate of approximately $3.6 million (after giving effect to voluntary employee separations). As a result, an aggregate of 337,847 2015 MYLTIP Units that had been previously granted were automatically forfeited. On February 6, 2018, Boston Properties, Inc.’s Compensation Committee approved the 2018 Multi-Year Long-Term Incentive Program (the “2018 MYLTIP”) awards under Boston Properties, Inc.’s 2012 Plan to certain officers and employees of Boston Properties, Inc. The 2018 MYLTIP awards utilize Boston Properties, Inc.’s total stockholder return (“TSR”) over a three-year measurement period, on an annualized, compounded basis, as the performance metric. Earned awards will be based on Boston Properties, Inc.’s TSR relative to (i) the Cohen & Steers Realty Majors Portfolio Index (50% weight) and (ii) the Nareit Office Index adjusted to include Vornado Realty Trust (50% weight). Earned awards will range from zero to a maximum of approximately $32.3 million depending on Boston Properties, Inc.’s TSR relative to the two indices, with a target of approximately $16.2 million and linear interpolation between zero and maximum. Earned awards measured on the basis of relative TSR performance are subject to an absolute TSR component in the form of relatively simple modifiers that (A) reduce the level of earned awards in the event Boston Properties, Inc.’s annualized TSR is less than 0% and (B) cause some awards to be earned in the event Boston Properties, Inc.’s annualized TSR is more than 12% even though on a relative basis alone Boston Properties, Inc.’s TSR would not result in any earned awards. Earned awards (if any) will vest 50% on February 5, 2021 and 50% on February 5, 2022, 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 5, 2021, earned awards will be calculated based on TSR performance up to the date of the change of control. The 2018 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. Under ASC 718, the 2018 MYLTIP awards have an aggregate value of approximately $13.3 million, which amount will generally be amortized into earnings over the four-year plan period under the graded vesting method. On February 23, 2018, the Company entered into a lease agreement with Fannie Mae to lease approximately 850,000 net rentable square feet of Class A office space at the Company's Reston Gateway development project located in Reston, Virginia. The initial phase of the project will consist of approximately 1.0 million net rentable square feet. The Company expects to begin construction in the second half of 2018 upon receipt of all necessary approvals.

20. Subsequent Events

On January 9, 2018, the Company completed the sale of its 500 E Street, S.W. property located in Washington, DC for a net contract sale price of approximately $118.6 million, which exceeds its carrying value. 500 E Street, S.W. is an approximately 262,000 net rentable square foot Class A office property.

On January 24, 2018, the Company entered into a lease agreement with a tenant for a build-to-suit project with approximately 276,000 net rentable square feet of Class A office space at the Company's 17Fifty Presidents Street development project located in Reston, Virginia. The Company expects that the building will be complete and available for occupancy during the first quarter of 2020.

On January 31, 2018, the Company partially placed in-service its Signature at Reston development project comprised of 508 apartment units and retail space aggregating approximately 515,000 square feet located in Reston, Virginia.

On February 2, 2018 and February 6, 2018, Boston Properties, Inc. issued an aggregate of 18,226 shares of restricted common stock and Boston Properties Limited Partnership issued an aggregate of 195,546 LTIP units under the 2012 Plan to certain employees of Boston Properties, Inc.

On February 4, 2018, the measurement period for the Company’s 2015 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 22.0% of target or an aggregate of approximately $3.6 million (after giving effect to voluntary employee separations). As a result, an aggregate of 337,847 2015 MYLTIP Units that had been previously granted were automatically forfeited.

On February 6, 2018, Boston Properties, Inc.’s Compensation Committee approved the 2018 Multi-Year Long-Term Incentive Program (the “2018 MYLTIP”) awards under Boston Properties, Inc.’s 2012 Plan to certain officers and employees of Boston Properties, Inc. The 2018 MYLTIP awards utilize Boston Properties, Inc.’s total stockholder return (“TSR”) over a three-year measurement period, on an annualized, compounded basis, as the performance metric. Earned awards will be based on Boston Properties, Inc.’s TSR relative to (i) the Cohen & Steers Realty Majors Portfolio Index (50% weight) and (ii) the Nareit Office Index adjusted to include Vornado Realty Trust (50% weight). Earned awards will range from zero to a maximum of approximately $32.3 million depending on Boston Properties, Inc.’s TSR relative to the two indices, with a target of approximately $16.2 million and linear interpolation between zero and maximum. Earned awards measured on the basis of relative TSR performance are subject to an absolute TSR component in the form of relatively simple modifiers that (A) reduce the level of earned awards in the event Boston Properties, Inc.’s annualized TSR is less than 0% and (B) cause some awards to be earned in the event Boston Properties, Inc.’s annualized TSR is more than 12% even though on a relative basis alone Boston Properties, Inc.’s TSR would not result in any earned awards. Earned awards (if any) will vest 50% on February 5, 2021 and 50% on February 5, 2022, 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 5, 2021, earned awards will be calculated based on TSR performance up to the date of the change of control. The 2018 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. Under ASC 718, the 2018 MYLTIP awards have an aggregate value of approximately $13.3 million, which amount will generally be amortized into earnings over the four-year plan period under the graded vesting method.

On February 23, 2018, the Company entered into a lease agreement with Fannie Mae to lease approximately 850,000 net rentable square feet of Class A office space at the Company's Reston Gateway development project located in Reston, Virginia. The initial phase of the project will consist of approximately 1.0 million net rentable square feet. The Company expects to begin construction in the second half of 2018 upon receipt of all necessary approvals.