Earnings Per Share / Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic Earnings:
Net income attributable to the Company's common shareholders / unitholders	$ 119,118	$ 117,337	$ 423,835	$ 348,086
Net income attributable to the Company's common shareholders / unitholders (in shares / units)	154,440,000	154,355,000	154,414,000	154,132,000
Net income (in dollars per share / unit)	$ 0.77	$ 0.76	$ 2.74	$ 2.26
Allocation of undistributed earnings to participating securities (numerator)		$ (7)	$ (87)	$ (15)
Allocation of undistributed earnings to participating securities (in shares)		0	0	0
Allocation of undistributed earnings to participating securities (in dollars per shares / units)		$ 0	$ 0	$ 0
Net income attributable to the Company's common shareholders / unitholders		$ 117,330	$ 423,748	$ 348,071
Net income attributable to the Company's common shareholders / unitholders (in shares / units)		154,355,000	154,414,000	154,132,000
Net income attributable to the Company's common shareholders / unitholders (in dollars per share / unit)		$ 0.76	$ 2.74	$ 2.26
Effect of Dilutive Securities:
Stock Based Compensation, Income (Numerator)	$ 0	$ 0	$ 0	$ 0
Stock Based Compensation, Shares / Units (Denominator)	238,000	128,000	238,000	212,000
Stock Based Compensation, Per Share / Unit Amount (in dollars per share / unit)	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Diluted Earnings:
Net income attributable to the Company's common shareholders / unitholders (Numerator)	$ 119,118	$ 117,330	$ 423,748	$ 348,071
Net income attributable to to the Company's shareholders / unitholder (number of shares)	154,678,000	154,483,000	154,652,000	154,344,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 0.77	$ 0.76	$ 2.74	$ 2.26
Boston Properties Limited Partnership
Entity Information [Line Items]
Redeemable Common Units	17,488,000	17,336,000	17,490,000	17,517,000
Basic Earnings:
Net income attributable to the Company's common shareholders / unitholders	$ 136,201	$ 132,693	$ 483,069	$ 395,199
Net income attributable to the Company's common shareholders / unitholders (in shares / units)	171,928,000	171,691,000	171,904,000	171,649,000
Net income (in dollars per share / unit)	$ 0.79	$ 0.77	$ 2.81	$ 2.30
Allocation of undistributed earnings to participating securities (numerator)		$ (8)	$ (97)	$ (17)
Allocation of undistributed earnings to participating securities (in shares)		0	0	0
Allocation of undistributed earnings to participating securities (in dollars per shares / units)		$ 0	$ 0	$ 0.00
Net income attributable to the Company's common shareholders / unitholders		$ 132,685	$ 482,972	$ 395,182
Net income attributable to the Company's common shareholders / unitholders (in shares / units)		171,691,000	171,904,000	171,649,000
Net income attributable to the Company's common shareholders / unitholders (in dollars per share / unit)		$ 0.77	$ 2.81	$ 2.30
Effect of Dilutive Securities:
Stock Based Compensation, Income (Numerator)	$ 0	$ 0	$ 0	$ 0
Stock Based Compensation, Shares / Units (Denominator)	238,000	128,000	238,000	212,000
Stock Based Compensation, Per Share / Unit Amount (in dollars per share / unit)	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Diluted Earnings:
Net income attributable to the Company's common shareholders / unitholders (Numerator)	$ 136,201	$ 132,685	$ 482,972	$ 395,182
Net income attributable to to the Company's shareholders / unitholder (number of shares)	172,166,000	171,819,000	172,142,000	171,861,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 0.79	$ 0.77	$ 2.81	$ 2.30