Subsequent Events	3 Months Ended
Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	12. Subsequent Events On April 19, 2017, the Company completed the sale of a parcel of land at 30 Shattuck Road located in Andover, Massachusetts for a gross sale price of approximately $5.0 million. On April 21, 2017, the Company exercised its option to ground lease, with the future right to purchase, real property adjacent to the MacArthur BART station located in Oakland, California, that could support the development of a 402-unit residential building and supporting retail space. On April 24, 2017, Boston Properties Limited Partnership executed the Eighth Amended and Restated Credit Agreement (as amended and restated, the “2017 Credit Facility”). Among other things, the amendment and restatement (1) increased the total commitment of the revolving line of credit (the “Revolving Facility”) from $1.0 billion to $1.5 billion, (2) extended the maturity date from July 26, 2018 to April 24, 2022, (3) reduced the per annum variable interest rates, and (4) added a $500.0 million delayed draw term loan facility (the “Delayed Draw Facility”) that permits Boston Properties Limited Partnership to borrow until the first anniversary of the closing date. The Delayed Draw Facility was undrawn at closing. Based on Boston Properties Limited Partnership’s current credit rating, (1) the applicable Eurocurrency margins for the Revolving Facility and Delayed Draw Facility are 87.5 basis points and 95 basis points, respectively, and (2) the facility fee on the Revolving Facility commitment is 0.15%. The Delayed Draw Facility has a fee on unused commitments equal to 0.15% per annum. On April 24, 2017, the Company’s consolidated entity in which it has a 60% interest and that owns 767 Fifth Avenue (the General Motors Building) located in New York City entered into an interest rate lock and commitment agreement with a group of lenders on a ten-year financing totaling $2.3 billion at a fixed interest rate of 3.43% per annum. The Company expects to close on the financing by the end of June 2017, although there can be no assurance that the financing will be consummated on the terms currently contemplated or at all. In conjunction with the interest rate lock and commitment agreement, the consolidated entity terminated its forward-starting interest rate swap contracts with notional amounts aggregating $450.0 million and paid approximately $14.4 million, which amount will increase the Company’s interest expense over the ten-year term of the financing, resulting in an estimated effective interest rate of approximately 3.65% per annum, inclusive of other estimated amortization of financing costs and additional mortgage recording taxes (See Note 5). On May 1, 2017, the Company entered into an agreement to acquire 103 Carnegie Center located in Princeton, New Jersey within the Company’s Carnegie Center office complex for a purchase price of approximately $15.8 million. 103 Carnegie Center is an approximately 96,000 net rentable square foot Class A office property. The Company expects that the acquisition will close during the second quarter of 2017. However, the acquisition is subject to the satisfaction of customary closing conditions and there can be no assurance that the acquisition will be consummated on the terms currently contemplated or at all.

12. Subsequent Events

On April 19, 2017, the Company completed the sale of a parcel of land at 30 Shattuck Road located in Andover, Massachusetts for a gross sale price of approximately $5.0 million.

On April 21, 2017, the Company exercised its option to ground lease, with the future right to purchase, real property adjacent to the MacArthur BART station located in Oakland, California, that could support the development of a 402-unit residential building and supporting retail space.

On April 24, 2017, Boston Properties Limited Partnership executed the Eighth Amended and Restated Credit Agreement (as amended and restated, the “2017 Credit Facility”). Among other things, the amendment and restatement (1) increased the total commitment of the revolving line of credit (the “Revolving Facility”) from $1.0 billion to $1.5 billion, (2) extended the maturity date from July 26, 2018 to April 24, 2022, (3) reduced the per annum variable interest rates, and (4) added a $500.0 million delayed draw term loan facility (the “Delayed Draw Facility”) that permits Boston Properties Limited Partnership to borrow until the first anniversary of the closing date. The Delayed Draw Facility was undrawn at closing. Based on Boston Properties Limited Partnership’s current credit rating, (1) the applicable Eurocurrency margins for the Revolving Facility and Delayed Draw Facility are 87.5 basis points and 95 basis points, respectively, and (2) the facility fee on the Revolving Facility commitment is 0.15%. The Delayed Draw Facility has a fee on unused commitments equal to 0.15% per annum.

On April 24, 2017, the Company’s consolidated entity in which it has a 60% interest and that owns 767 Fifth Avenue (the General Motors Building) located in New York City entered into an interest rate lock and commitment agreement with a group of lenders on a ten-year financing totaling $2.3 billion at a fixed interest rate of 3.43% per annum. The Company expects to close on the financing by the end of June 2017, although there can be no assurance that the financing will be consummated on the terms currently contemplated or at all. In conjunction with the interest rate lock and commitment agreement, the consolidated entity terminated its forward-starting interest rate swap contracts with notional amounts aggregating $450.0 million and paid approximately $14.4 million, which amount will increase the Company’s interest expense over the ten-year term of the financing, resulting in an estimated effective interest rate of approximately 3.65% per annum, inclusive of other estimated amortization of financing costs and additional mortgage recording taxes (See Note 5).

On May 1, 2017, the Company entered into an agreement to acquire 103 Carnegie Center located in Princeton, New Jersey within the Company’s Carnegie Center office complex for a purchase price of approximately $15.8 million. 103 Carnegie Center is an approximately 96,000 net rentable square foot Class A office property. The Company expects that the acquisition will close during the second quarter of 2017. However, the acquisition is subject to the satisfaction of customary closing conditions and there can be no assurance that the acquisition will be consummated on the terms currently contemplated or at all.