(Common Units) (Narrative) (Details) (USD $)	0 Months Ended	3 Months Ended	0 Months Ended
	Jan. 28, 2015	Mar. 31, 2015 Y	Feb. 06, 2015	Mar. 18, 2015
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares)		258,599
Redemption of OP units issued on conversion of LTIP Units (in shares)		46,992
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
Distribution paid to outperformance awards, OPP Units and MYLTIP Units (in dollars per share)	$ 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		$ 2,500,000,000
Closing price of common stock (in dollars per share)		$ 140.48
2013 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2013 MYLTIP (in shares)		309,818
MYLTIP 2014 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2014 MYLTIP (in shares)		476,320
2015 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2015 MYLTIPS (in shares)		368,415
Quarter 4 2014 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date		Jan. 28, 2015
Quarter 4 2014 [Member] | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date		Jan. 28, 2015
Holders of record date		Dec. 31, 2014
Quarter 1 2015 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date		Apr. 30, 2015
Dividends payable, date declared		Mar. 18, 2015
Quarter 1 2015 [Member] | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Dividend payable date		Apr. 30, 2015
Holders of record date		Mar. 31, 2015
Dividends payable, date declared		Mar. 18, 2015
special dividend [Member] | OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distributions made to OP and LTIP units per unit (in dollars per share)	$ 4.50
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards earned			32,100,000
Potential maximum amount of Outperformance Awards earned (percent)			80.00%
Potential Awards Earned			$ 40,000,000
2012 OPP Units Forfeited (in shares)			174,549