Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
ASSETS
Real estate, at cost	$ 13,389,472	$ 12,764,935
Less: accumulated depreciation	(2,642,986)	(2,323,818)
Total real estate	10,746,486	10,441,117
Cash and cash equivalents	1,823,208	478,948
Cash held in escrows	40,332	308,031
Investments in securities	9,548	8,732
Tenant and other receivables (net of allowance for doubtful accounts of $1,766 and $2,081, respectively)	79,838	60,813
Related party notes receivable	280,442	270,000
Interest receivable from related party notes receivable	89,854	69,005
Accrued rental income (net of allowance of $2,515 and $3,116, respectively)	522,675	442,683
Deferred charges, net	445,403	436,019
Prepaid expenses and other assets	75,458	65,663
Investments in unconsolidated joint ventures	669,722	767,252
Total assets	14,782,966	13,348,263
Liabilities:
Mortgage notes payable, net	3,123,267	3,047,586
Unsecured senior notes (net of discount of $9,814 and $8,402, respectively)	3,865,186	3,016,598
Unsecured exchangeable senior notes (net of discount of $3,462 and $8,249, respectively)	1,715,685	1,721,817
Unsecured line of credit
Accounts payable and accrued expenses	155,139	161,592
Dividends and distributions payable	91,901	81,031
Accrued interest payable	69,105	62,327
Other liabilities	293,515	237,467
Total liabilities	9,313,798	8,328,418
Commitments and contingencies
Noncontrolling interest:
Redeemable preferred units of the Operating Partnership	55,652	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, 148,186,511 and 140,278,005 issued and 148,107,611 and 140,199,105 outstanding at December 31, 2011 and 2010, respectively	1,481	1,402
Additional paid-in capital	4,936,457	4,417,162
Dividends in excess of earnings	(53,080)	(24,763)
Treasury common stock at cost, 78,900 shares at December 31, 2011 and 2010	(2,722)	(2,722)
Accumulated other comprehensive loss	(16,138)	(18,436)
Total stockholders' equity attributable to Boston Properties, Inc.	4,865,998	4,372,643
Noncontrolling interests:
Common units of the Operating Partnership	548,581	592,164
Property partnerships	(1,063)	(614)
Total equity	5,413,516	4,964,193
Total liabilities and equity	$ 14,782,966	$ 13,348,263