Subsequent Events subsequent Events (Details)	Feb. 23, 2018 ft²	Feb. 06, 2018 USD ($) yr indices shares	Feb. 04, 2018 USD ($) shares	Feb. 02, 2018 shares	Jan. 31, 2018 ft² apartments	Jan. 24, 2018 ft²	Jan. 09, 2018 USD ($) ft²	Dec. 31, 2017 shares	Dec. 31, 2016 shares	May 17, 2016 shares
Subsequent Event [Line Items]
Common stock, shares issued | shares								154,404,186	153,869,075	1,507
Subsequent Event [Member] | MYLTIP 2015 [Member]
Subsequent Event [Line Items]
Final awards percentage of target			22.00%
Value of MYLTIP Awards			$ 3,600,000
MYLTIP Units forfeited | shares			337,847
Subsequent Event [Member] | MYLTIPS 2018 [Member]
Subsequent Event [Line Items]
Target Tier		$ 16,200,000
Indices Used to Compare TSR | indices		2
Percentage of annualized TSR for Reduction of Earned Awards		0.00%
Percentage to Cause Some Awards to be Earned Even if on a Relative Basis it Would Not Result in any Earned Awards		12.00%
Distributions percent before measurement date		10.00%
Value of MYLTIP Awards		$ 13,300,000
MYLTIP Value Amortized Into Earnings, Years | yr		4
TSR measurement (in years) | yr		3
Subsequent Event [Member] | MYLTIPS 2018 [Member] | Cohen & Steers Realty Majors Portfolio Index [Member]
Subsequent Event [Line Items]
Weighted Percentage of Index Used to Compare to TSR		50.00%
Subsequent Event [Member] | MYLTIPS 2018 [Member] | NAREIT Office Index adjusted [Member]
Subsequent Event [Line Items]
Weighted Percentage of Index Used to Compare to TSR		50.00%
Subsequent Event [Member] | Minimum [Member] | MYLTIPS 2018 [Member]
Subsequent Event [Line Items]
Potential Awards Earned		$ 0
Subsequent Event [Member] | Maximum [Member] | MYLTIPS 2018 [Member]
Subsequent Event [Line Items]
Potential Awards Earned		$ 32,300,000
Subsequent Event [Member] | MYLTIP vesting 2021 | MYLTIPS 2018 [Member]
Subsequent Event [Line Items]
Vesting Percentage		50.00%
Subsequent Event [Member] | MYLTIP vesting 2022 | MYLTIPS 2018 [Member]
Subsequent Event [Line Items]
Vesting Percentage		50.00%
Subsequent Event [Member] | Restricted Stock [Member]
Subsequent Event [Line Items]
Common stock, shares issued | shares				18,226
Boston Properties Limited Partnership | Subsequent Event [Member] | LTIP Units [Member]
Subsequent Event [Line Items]
LTIP units issued (in shares) | shares		195,546
500 E Street | Subsequent Event [Member]
Subsequent Event [Line Items]
Net Contractual Sales Price							$ 118,600,000
Net Rentable Area | ft²							262,000
17Fifty Presidents Street [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Net Rentable Area | ft²						276,000
Signature at Reston | Subsequent Event [Member]
Subsequent Event [Line Items]
Net Rentable Area | ft²					515,000
Number of apartment units | apartments					508
Reston Gateway | Subsequent Event [Member]
Subsequent Event [Line Items]
Net Rentable Area | ft²	1,000,000.0
Square Footage Of Signed Lease | ft²	850,000