Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
ASSETS
Real estate, at cost	$ 12,937,143	$ 12,303,965
Construction in progress	870,006	818,685
Land held for future development	268,030	266,822
Less: accumulated depreciation	(2,722,605)	(2,642,986)
Total real estate	11,352,574	10,746,486
Cash and cash equivalents	591,196	1,823,208
Cash held in escrows	30,697	40,332
Investments in securities	11,193	9,548
Tenant and other receivables (net of allowance for doubtful accounts of $1,370 and $1,766, respectively)	68,275	79,838
Related party notes receivable	281,177	280,442
Interest receivable from related party notes receivable	95,126	89,854
Accrued rental income (net of allowance of $2,631 and $2,515, respectively)	541,153	522,675
Deferred charges, net	500,957	445,403
Prepaid expenses and other assets	73,132	75,458
Investments in unconsolidated joint ventures	667,377	669,722
Total assets	14,212,857	14,782,966
Liabilities:
Mortgage notes payable	2,946,760	3,123,267
Unsecured senior notes (net of discount of $9,631 and $9,814, respectively)	3,865,369	3,865,186
Unsecured exchangeable senior notes (net of discount of $2,720 and $3,462, respectively)	1,148,497	1,715,685
Unsecured line of credit
Accounts payable and accrued expenses	165,441	155,139
Dividends and distributions payable	92,615	91,901
Accrued interest payable	97,997	69,105
Other liabilities	324,826	293,515
Total liabilities	8,641,505	9,313,798
Commitments and contingencies
Noncontrolling interest:
Redeemable preferred units of the Operating Partnership	51,537	55,652
Equity:
Excess stock, $.01 par value, 150,000,000 shares authorized, none issued or outstanding
Preferred stock, $.01 par value, 50,000,000 shares authorized, none issued or outstanding
Common stock, $.01 par value, 250,000,000 shares authorized, 149,463,241 and 148,186,511 issued and 149,384,341 and 148,107,611 outstanding at March 31, 2012 and December 31, 2011, respectively	1,494	1,481
Additional paid-in capital	5,050,547	4,936,457
Dividends in excess of earnings	(70,609)	(53,080)
Treasury common stock at cost, 78,900 shares at March 31, 2012 and December 31, 2011	(2,722)	(2,722)
Accumulated other comprehensive loss	(15,558)	(16,138)
Total stockholders' equity attributable to Boston Properties, Inc.	4,963,152	4,865,998
Noncontrolling interests:
Common units of the Operating Partnership	557,930	548,581
Property partnerships	(1,267)	(1,063)
Total equity	5,519,815	5,413,516
Total liabilities and equity	$ 14,212,857	$ 14,782,966