Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
ASSETS
Real estate, at cost	$ 17,059,235	$ 13,581,454
Construction in progress	1,483,114	1,036,780
Land held for future development	290,085	275,094
Less: accumulated depreciation	(2,996,520)	(2,934,160)
Total real estate	15,835,914	11,959,168
Cash and cash equivalents	1,608,731	1,041,978
Cash held in escrows	54,829	55,181
Investments in securities	14,226	12,172
Tenant and other receivables (net of allowance for doubtful accounts of $1,377 and $1,960, respectively)	66,039	69,555
Related party notes receivable	0	282,491
Interest receivable from related party notes receivable	0	104,816
Accrued rental income (net of allowance of $3,641 and $1,653, respectively)	625,654	598,199
Deferred charges, net	939,675	588,235
Prepaid expenses and other assets	179,741	90,610
Investments in unconsolidated joint ventures	137,975	659,916
Total assets	19,462,784	15,462,321
Liabilities:
Mortgage notes payable	4,484,657	3,102,485
Unsecured senior notes (net of discount of $15,027 and $10,472, respectively)	5,834,973	4,639,528
Unsecured exchangeable senior notes (net of discount of $924 and $1,653, respectively)	734,278	1,170,356
Unsecured line of credit	0	0
Mezzanine notes payable	311,637	0
Related party notes payable	180,000	0
Accounts payable and accrued expenses	212,998	199,102
Dividends and distributions payable	112,425	110,488
Accrued interest payable	141,676	72,461
Other liabilities	556,730	324,613
Total liabilities	12,569,374	9,619,033
Commitments and contingencies	0	0
Noncontrolling interest:
Redeemable preferred units of the Operating Partnership	110,876	110,876
Redeemable interest in property partnerships	98,162	97,558
Equity:
Excess stock, $.01 par value, 150,000,000 shares authorized, none issued or outstanding	0	0
Preferred stock, $.01 par value, 50,000,000 shares authorized
5.25% Series B cumulative redeemable preferred stock, $.01 par value, liquidation preference of $2,500 per share, 92,000 shares authorized, 80,000 and no shares issued and outstanding at June 30, 2013 and December 31,2012, respectively	200,000	0
Common stock, $.01 par value, 250,000,000 shares authorized, 152,463,640 and 151,680,109 issued and 152,384,740 and 151,601,209 outstanding at June 30, 2013 and December 31, 2012, respectively	1,524	1,516
Additional paid-in capital	5,246,243	5,222,073
Dividends in excess of earnings	192,492	(109,985)
Treasury common stock at cost, 78,900 shares at June 30, 2013 and December 31, 2012	(2,722)	(2,722)
Accumulated other comprehensive loss	(12,689)	(13,817)
Total stockholders' equity attributable to Boston Properties, Inc.	5,624,848	5,097,065
Noncontrolling interests:
Common units of the Operating Partnership	570,135	539,753
Property partnerships	489,389	(1,964)
Total equity	6,684,372	5,634,854
Total liabilities and equity	$ 19,462,784	$ 15,462,321