Related Party Disclosures	12 Months Ended
Related Party Disclosures	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions Disclosure	17. Related Party Transactions A firm controlled by Mr. Raymond A. Ritchey’s brother was paid aggregate leasing commissions of approximately $914,000, $21,000 and $921,000 during the years ended December 31, 2020, 2019 and 2018, respectively, related to certain exclusive leasing arrangements for certain Northern Virginia properties. In addition, Mr. Ritchey’s brother is employed by a real estate brokerage firm and participated in brokerage activities for which the Company paid the firm approximately $3.4 million and $2.6 million for the years ended December 31, 2020 and 2019, respectively. Mr. Ritchey’s brother did not participate in brokerage activities related to such arrangement during the year ended December 31, 2018. Mr. Ritchey is a Senior Executive Vice President of Boston Properties, Inc. In accordance with Boston Properties, Inc.’s 2012 Plan, and as approved by its Board of Directors, seven non-employee directors made elections to receive deferred stock units in lieu of cash fees for 2020. As a result of these elections, the aggregate cash fees otherwise payable to a non-employee director during a fiscal quarter are converted into a number of deferred stock units equal to the aggregate cash fees divided by the last reported sales price of a share of Boston Properties, Inc.’s Common Stock on the last trading of the applicable fiscal quarter. The deferred stock units are also credited with dividend equivalents as dividends are paid by Boston Properties, Inc. The deferred stock units may be settled in shares of Common Stock upon the cessation of such director’s service on the Board of Directors of Boston Properties, Inc. The non-employee director compensation program provides, subject to certain conditions, the non-employee directors holding deferred stock units with the ability to elect, following cessation of their service on the Company’s Board of Directors, to diversify their investment elections into non-employer securities on a pre-tax basis and receive tax-deferred returns on such deferrals, which will ultimately be settled in cash. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the non-employee director in the future. At December 31, 2020 and 2019, the Company had maintained approximately $0.8 million and $0.7 million, respectively, in a separate account, which is not restricted as to its use. The Company’s liability under the plan is equal to the total amount of compensation deferred by the non-employee director and earnings on the deferred compensation pursuant to investments elected by the non-employee director. The Company’s liability as of December 31, 2020 and 2019 was approximately $0.8 million and $0.7 million, respectively, which is included in the accompanying Consolidated Balance Sheets. The terms of the non-employee director compensation program require the classification of these deferred stock units as temporary equity on the Consolidated Balance Sheets of Boston Properties, Inc. and Boston Properties Limited Partnership within Redeemable Deferred Stock Units. On May 21, 2019, in connection with the cessation of a director’s service on the Board of Directors of Boston Properties, Inc., Boston Properties, Inc. issued 17,949 shares of Common Stock in settlement of a portion of the director’s outstanding deferred stock units. In addition, on September 3, 2019, the Company converted 4,917 of such director’s deferred stock units as a result of such director’s election to diversify their investment elections into non-employer securities. At December 31, 2020 and 2019, Boston Properties, Inc. had outstanding 72,966 and 60,676 deferred stock units, respectively.