(Common Units) (Narrative) (Details) (USD $)	0 Months Ended			9 Months Ended
	Jul. 31, 2013	Apr. 30, 2013	Jan. 29, 2013	Sep. 30, 2013 Y	Sep. 18, 2013
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares)				336,935
Redemption of OP units issued on conversion of LTIP Units (in shares)				19,589
Outperformance Awards LTIP Units distribution as percentage of OP Unit distribution prior to measurement date				10.00%
Distributions made to OP and LTIP units per unit (in dollars per share)	$ 0.65	$ 0.65	$ 0.65
Distribution paid to outperformance awards, OPP Units (in dollars per share)	$ 0.065	$ 0.065	$ 0.065
Distribution declared to OP and LTIP units by Boston Properties, Inc. (in dollars per share)					$ 0.65
Distribution declared to outperformance awards OPP Units by Boston Properties, Inc. (in dollars per share)					$ 0.065
Restriction on redemption of OP Unit to Common Stock (in years)				1
Redemption of OP Unit equivalence to Common Stock (in shares)				1
Common units of operating partnership if converted value				$ 1,800,000,000
Value of Series Two Preferred Units assuming conversion				$ 139,700,000
OPP Units 2011 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)				396,500
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)				396,150
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Closing price of common stock (in dollars per share)				$ 106.90
Quarter 4 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date				Jan. 29, 2013
Quarter 4 2012 [Member] | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date				Jan. 29, 2013
Holders of record date				Dec. 31, 2012
Quarter 1 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date				Apr. 30, 2013
Quarter 1 2013 [Member] | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date				Apr. 30, 2013
Holders of record date				Mar. 29, 2013
Quarter 2 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date				Jul. 31, 2013
Quarter 2 2013 [Member] | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date				Jul. 31, 2013
Holders of record date				Jun. 28, 2013
Quarter 3 2013 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date				Oct. 31, 2013
Dividends payable, date declared				Sep. 18, 2013
Quarter 3 2013 [Member] | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date				Oct. 31, 2013
Holders of record date				Sep. 30, 2013
Dividends payable, date declared				Sep. 18, 2013