Earnings Per Share / Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic Earnings:
Net income attributable to the Company's common shareholders / unitholders	$ 107,771	$ 119,118	$ 370,200	$ 423,835
Net income attributable to the Company's common shareholders / unitholders (in shares / units)	154,577,000	154,440,000	154,553,000	154,414,000
Net income (in dollars per share / unit)	$ 0.70	$ 0.77	$ 2.40	$ 2.74
Allocation of undistributed earnings to participating securities				$ (87)
Allocation of undistributed earnings to participating securities (in shares)				0
Allocation of undistributed earnings to participating securities (in dollars per shares / units)				$ 0
Net income attributable to the Company's common shareholders / unitholders				$ 423,748
Net income attributable to the Company's common shareholders / unitholders (in shares / units)				154,414,000
Net income attributable to the Company's common shareholders / unitholders (in dollars per share / unit)				$ 2.74
Effect of Dilutive Securities:
Stock Based Compensation, Income (Numerator)	$ 0	$ 0	$ 0	$ 0
Stock Based Compensation, Income (in shares / units)	243,000	238,000	294,000	238,000
Stock Based Compensation, Income (in dollars per share / unit)	$ 0	$ 0	$ (0.01)	$ 0
Diluted Earnings:
Net income attributable to the Company's common shareholders / unitholders (Numerator)	$ 107,771	$ 119,118	$ 370,200	$ 423,748
Net income attributable to to the Company's shareholders / unitholder (number of shares)	154,820,000	154,678,000	154,847,000	154,652,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 0.70	$ 0.77	$ 2.39	$ 2.74
Boston Properties Limited Partnership
Entity Information [Line Items]
Redeemable Common Units	17,638,000	17,488,000	17,630,000	17,490,000
Basic Earnings:
Net income attributable to the Company's common shareholders / unitholders	$ 122,117	$ 136,201	$ 421,214	$ 483,069
Net income attributable to the Company's common shareholders / unitholders (in shares / units)	172,215,000	171,928,000	172,183,000	171,904,000
Net income (in dollars per share / unit)	$ 0.71	$ 0.79	$ 2.45	$ 2.81
Allocation of undistributed earnings to participating securities				$ (97)
Allocation of undistributed earnings to participating securities (in shares)				0
Allocation of undistributed earnings to participating securities (in dollars per shares / units)				$ 0
Net income attributable to the Company's common shareholders / unitholders				$ 482,972
Net income attributable to the Company's common shareholders / unitholders (in shares / units)				171,904,000
Net income attributable to the Company's common shareholders / unitholders (in dollars per share / unit)				$ 2.81
Effect of Dilutive Securities:
Stock Based Compensation, Income (Numerator)	$ 0	$ 0	$ 0	$ 0
Stock Based Compensation, Income (in shares / units)	243,000	238,000	294,000	238,000
Stock Based Compensation, Income (in dollars per share / unit)	$ 0	$ 0	$ (0.01)	$ 0
Diluted Earnings:
Net income attributable to the Company's common shareholders / unitholders (Numerator)	$ 122,117	$ 136,201	$ 421,214	$ 482,972
Net income attributable to to the Company's shareholders / unitholder (number of shares)	172,458,000	172,166,000	172,477,000	172,142,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 0.71	$ 0.79	$ 2.44	$ 2.81