Basis Of Presentation And Summary Of Significant Accounting Policies (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)
Entity Information [Line Items]
Cumulative effect of a change in accounting principle	$ 2,035
Boston Properties Limited Partnership
Entity Information [Line Items]
Cumulative effect of a change in accounting principle	272
Noncontrolling Interests [Member]
Entity Information [Line Items]
Cumulative effect of a change in accounting principle	1,763
Noncontrolling Interests [Member] | Boston Properties Limited Partnership
Entity Information [Line Items]
Cumulative effect of a change in accounting principle	$ 1,763