Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Development and management services income									$ 25,316	$ 29,695	$ 34,060
Income from unconsolidated joint ventures									12,769	75,074	49,078
Gains on consolidation of joint ventures									0	385,991	0
Interest and other income									8,765	8,310	10,091
Gains from investments in securities									1,038	2,911	1,389
(Losses) gains from early extinguishments of debt									(10,633)	122	(4,453)
Income from discontinued operations									0	8,022	9,806
Gains on sales of real estate from discontinued operations									0	112,829	36,877
Gain on forgiveness of debt from discontinued operations									0	20,182	0
Gains on sales of real estate									168,039	0	0
General and administrative expense									98,937	115,329	90,129
Transaction costs									3,140	1,744	3,653
Depreciation and amortization expense									628,573	560,637	445,875
Interest expense									455,743	446,880	410,970
Impairment loss									0	8,306	0
Impairment loss from discontinued operations									0	3,241	0
Noncontrolling interest in property partnerships									30,561	1,347	3,792
Noncontrolling interest-redeemable preferred units of the Operating Partnership									1,023	6,046	3,497
Noncontrolling interest-common units of the Operating Partnership									50,862	70,085	30,125
Noncontrolling interest in discontinued operations-common units of the Operating Partnership									0	14,151	5,075
Preferred dividends									10,500	8,057	0
Net income attributable to Boston Properties, Inc. common shareholders	174,510	127,724	76,527	54,034	88,719	152,677	452,417	47,854	433,111	741,754	289,650
Business Intersegment, Eliminations [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Operating Income									1,507,156	1,334,441	1,145,918
Development and management services income									25,316	29,695	34,060
Income from unconsolidated joint ventures									12,769	75,074	49,078
Gains on consolidation of joint ventures									0	385,991	0
Interest and other income									8,765	8,310	10,091
Gains from investments in securities									1,038	2,911	1,389
(Losses) gains from early extinguishments of debt									(10,633)	122	(4,453)
Income from discontinued operations									0	8,022	9,806
Gains on sales of real estate from discontinued operations									0	112,829	36,877
Gain on forgiveness of debt from discontinued operations									0	20,182	0
Gains on sales of real estate									168,039	0	0
General and administrative expense									98,937	115,329	90,129
Transaction costs									3,140	1,744	3,653
Depreciation and amortization expense									628,573	560,637	445,875
Interest expense									455,743	446,880	410,970
Impairment loss									0	8,306	0
Impairment loss from discontinued operations									0	3,241	0
Noncontrolling interest in property partnerships									30,561	1,347	3,792
Noncontrolling interest-redeemable preferred units of the Operating Partnership									1,023	6,046	3,497
Noncontrolling interest-common units of the Operating Partnership									50,862	70,085	30,125
Noncontrolling interest in discontinued operations-common units of the Operating Partnership									0	14,151	5,075
Preferred dividends									10,500	8,057	0
Net income attributable to Boston Properties, Inc. common shareholders									$ 433,111	$ 741,754	$ 289,650