Unsecured Exchangeable Senior Notes Schedule of Unsecured Exchangeable Senior Notes (Details) (USD $)				6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Aug. 15, 2008	Jun. 30, 2013 3.625% exchangeable senior notes [Member]
Debt Instrument [Line Items]
Coupon/Stated Rate				3.625%
Effective Percentage				4.037%	[1]
Exchange Rrate				8.5051	[2]
Principal Amount				$ 747,500,000
Maturity date				Feb. 15, 2014
Unsecured exchangeable senior notes, discount	(924,000)	(1,653,000)
Adjustment for the equity component allocation, net of accumulated amortization	(12,298,000)
Unsecured exchangeable senior notes	734,278,000	1,170,356,000
Increment Of The Notes For Purposes Of Disclosing Initial Exchange Rate	1,000
Initial Exchange Rate	8.5051
Debt Instrument, Convertible, Conversion Price	$ 117.58
Adjusted Exchange Price Due To Capped Call	$ 137.17
Premium Over Closing Price Due To Capped Call	40.00%
Share Price	$ 134.38		$ 97.98
Net Cost Of Capped Call Transaction	$ 44,400,000

[1] Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs but excluding the effects of the adjustment for the equity component allocation.

[2] The initial exchange rate is 8.5051 shares per $1,000 principal amount of the notes (or an initial exchange price of approximately $117.58 per share of Boston Properties, Inc.’s common stock). In addition, the Company entered into capped call transactions with affiliates of certain of the initial purchasers, which are intended to reduce the potential dilution upon future exchange of the notes. The capped call transactions were intended to increase the effective exchange price to the Company of the notes from $117.58 to approximately $137.17 per share (subject to adjustment), representing an overall effective premium of approximately 40% over the closing price on August 13, 2008 of $97.98 per share of Boston Properties, Inc.’s common stock. The net cost of the capped call transactions was approximately $44.4 million. As of June 30, 2013, the effective exchange price was $134.38 per share.