Real Estate Activity During the Nine Months Ended September 30, 2013 (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended						3 Months Ended			0 Months Ended	3 Months Ended	0 Months Ended	9 Months Ended	3 Months Ended		6 Months Ended		0 Months Ended	4 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Apr. 25, 2013 Siz Zero One Massachusetts Avenue [Member] sqft	Feb. 06, 2013 535 Mission [Member] floor sqft	Mar. 26, 2013 Transbay Tower [Member] floor sqft	Feb. 26, 2013 Transbay Tower [Member]	Feb. 07, 2013 Transbay Tower [Member]	Mar. 29, 2013 Reston Land Parcel [Member] sqft	Mar. 22, 2013 Two Patriots Park [Member] sqft	Mar. 31, 2013 Plaza at Almaden [Member]	Mar. 28, 2013 Plaza at Almaden [Member] sqft	Jun. 14, 2013 Seventeen Cambridge Center [Member] sqft	Aug. 22, 2013 1301 New York Avenue [Member] sqft	Sep. 30, 2013 1301 New York Avenue [Member]	Feb. 20, 2013 Montvale Center [Member]	Sep. 30, 2012 Montvale Center [Member]	Mar. 31, 2013 303 Almaden blvd [Member]	Mar. 28, 2013 303 Almaden blvd [Member] sqft	Sep. 30, 2013 Mountain View Research And Technology Parks [Member]	Apr. 10, 2013 Mountain View Research And Technology Parks [Member]	May 31, 2013 767 Fifth Avenue (The GM Building) [Member] partners sqft	Sep. 30, 2013 767 Fifth Avenue (The GM Building) [Member]	Apr. 10, 2013 Mountain View Research [Member] Buildings sqft	Apr. 10, 2013 Mountain View Technology [Member] Buildings sqft	Sep. 30, 2013 Cambridge Center Connector [Member] sqft
Real Estate Properties [Line Items]
Total revenue	$ 574,082,000	$ 466,680,000	$ 1,566,834,000	$ 1,376,448,000												$ 1,511,000					$ 10,900,000			$ 95,300,000
Operating income	189,389,000	162,735,000	494,953,000	480,458,000												1,078,000					(100,000)			4,100,000
Number of Joint Venture Partners																							2
Purchase Price			522,900,000	688,073,000		71,000,000
Number of floors real estate						27	60
Payments to Acquire Land							192,000,000			27,000,000
Partners Joint Venture Ownership Percentage								5.00%	50.00%
Net Rentable Area					478,000	307,000	1,400,000			250,000	256,000		840,000	195,000	201,000					158,000			1,800,000		604,000	135,000	43,000
Aggregate purchase price																						233,100,000
Impairment loss from discontinued operations	0	0	2,852,000	0												0			2,900,000
Ownership Percentage							95.00%	95.00%															40.00%
Amount of debt extinguished																		25,000,000
Gain on forgiveness of debt from discontinued operations attributable to Boston Properties LImited Partnership	0	0	20,736,000	0												0	20,700,000	18,400,000
Contractual Sales Price															135,000,000					40,000,000
Impairment loss	0	0	4,401,000	0								4,400,000
Net Contractual Sales Price															121,700,000
Number of real estate properties																									16	7
Proceeds from sales of real estate			160,815,000	61,963,000											121,500,000
Gains on sale of real estate from discontinued operations	$ 88,565,000	$ 0	$ 88,565,000	$ 38,445,000											$ 88,600,000	$ 88,565,000