Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $6,592,019 and $6,497,031 at December 31, 2020 and December 31, 2019, respectively)	$ 22,969,110	$ 22,502,976
Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2020 and December 31, 2019, respectively)	237,393	237,394
Right of use assets - operating leases	146,406	148,640
Less: accumulated depreciation (amounts related to VIEs of $(1,158,548) and $(1,058,495) at December 31, 2020 and December 31, 2019, respectively)	(5,534,102)	(5,266,798)
Total real estate	17,818,807	17,622,212
Cash and cash equivalents (amounts related to VIEs of $340,642 and $280,033 at December 31, 2020 and December 31, 2019, respectively)	1,668,742	644,950
Cash held in escrows	50,587	46,936
Investments in securities	39,457	36,747
Tenant and other receivables, net (amounts related to VIEs of $10,911 and $28,918 at December 31, 2020 and December 31, 2019, respectively)	77,411	112,807
Related party note receivable, net	77,552	80,000
Notes receivable, net	18,729	15,920
Accrued rental income, net (amounts related to VIEs of $336,594 and $298,318 at December 31, 2020 and December 31, 2019, respectively)	1,122,502	1,038,788
Deferred charges, net (amounts related to VIEs of $183,306 and $214,769 at December 31, 2020 and December 31, 2019, respectively)	640,085	689,213
Prepaid expenses and other assets (amounts related to VIEs of $13,137 and $20,931 at December 31, 2020 and December 31, 2019, respectively)	33,840	41,685
Investments in unconsolidated joint ventures	1,310,478	955,647
Total assets	22,858,190	21,284,905
Liabilities:
Mortgage notes payable, net (amounts related to VIEs of $2,907,590 and $2,918,806 at December 31, 2020 and December 31, 2019, respectively)	2,909,081	2,922,408
Unsecured senior notes, net	9,639,287	8,390,459
Unsecured line of credit	0	0
Unsecured term loan, net	499,390	498,939
Lease liabilities - finance leases (amounts related to VIEs of $20,306 and $20,189 at December 31, 2020 and December 31, 2019, respectively)	236,492	224,042
Lease liabilities - operating leases	201,713	200,180
Accounts payable and accrued expenses (amounts related to VIEs of $23,128 and $45,777 at December 31, 2020 and December 31, 2019, respectively)	336,264	377,553
Dividends and distributions payable	171,082	170,713
Accrued interest payable	106,288	90,016
Other liabilities (amounts related to VIEs of $158,805 and $140,110 at December 31, 2020 and December 31, 2019, respectively)	412,084	387,994
Total liabilities	14,511,681	13,262,304
Redeemable deferred stock units— 72,966 and 60,676 units outstanding at redemption value at December 31, 2020 and December 31, 2019, respectively	6,897	8,365
Equity / Capital:
Excess stock, $0.01 par value, 150,000,000 shares authorized, none issued or outstanding	0	0
Preferred stock, $0.01 par value, 50,000,000 shares authorized;
5.25% Series B cumulative redeemable preferred stock / units, liquidation preference $2,500 per share / unit, 80,000 shares / units issued and outstanding at December 31, 2020 and December 31, 2019, respectively	200,000	200,000
Common stock, $0.01 par value, 250,000,000 shares authorized, 155,797,725 and 154,869,198 issued and 155,718,825 and 154,790,298 outstanding at December 31, 2020 and December 31, 2019, respectively	1,557	1,548
Additional paid-in capital	6,356,791	6,294,719
Dividends in excess of earnings	(509,653)	(760,523)
Treasury common stock at cost, 78,900 shares at December 31, 2020 and December 31, 2019	(2,722)	(2,722)
Accumulated other comprehensive loss	(49,890)	(48,335)
Total stockholders' equity attributable to Boston Properties, Inc.	5,996,083	5,684,687
Noncontrolling interests:
Common units of the Operating Partnership	616,596	600,860
Property partnerships	1,726,933	1,728,689
Total equity / capital	8,339,612	8,014,236
Total liabilities and equity / capital	22,858,190	21,284,905
Boston Properties Limited Partnership
ASSETS
Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $6,592,019 and $6,497,031 at December 31, 2020 and December 31, 2019, respectively)	22,592,301	22,107,755
Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2020 and December 31, 2019, respectively)	237,393	237,394
Right of use assets - operating leases	146,406	148,640
Less: accumulated depreciation (amounts related to VIEs of $(1,158,548) and $(1,058,495) at December 31, 2020 and December 31, 2019, respectively)	(5,428,576)	(5,162,908)
Total real estate	17,547,524	17,330,881
Cash and cash equivalents (amounts related to VIEs of $340,642 and $280,033 at December 31, 2020 and December 31, 2019, respectively)	1,668,742	644,950
Cash held in escrows	50,587	46,936
Investments in securities	39,457	36,747
Tenant and other receivables, net (amounts related to VIEs of $10,911 and $28,918 at December 31, 2020 and December 31, 2019, respectively)	77,411	112,807
Related party note receivable, net	77,552	80,000
Notes receivable, net	18,729	15,920
Accrued rental income, net (amounts related to VIEs of $336,594 and $298,318 at December 31, 2020 and December 31, 2019, respectively)	1,122,502	1,038,788
Deferred charges, net (amounts related to VIEs of $183,306 and $214,769 at December 31, 2020 and December 31, 2019, respectively)	640,085	689,213
Prepaid expenses and other assets (amounts related to VIEs of $13,137 and $20,931 at December 31, 2020 and December 31, 2019, respectively)	33,840	41,685
Investments in unconsolidated joint ventures	1,310,478	955,647
Total assets	22,586,907	20,993,574
Liabilities:
Mortgage notes payable, net (amounts related to VIEs of $2,907,590 and $2,918,806 at December 31, 2020 and December 31, 2019, respectively)	2,909,081	2,922,408
Unsecured senior notes, net	9,639,287	8,390,459
Unsecured line of credit	0	0
Unsecured term loan, net	499,390	498,939
Lease liabilities - finance leases (amounts related to VIEs of $20,306 and $20,189 at December 31, 2020 and December 31, 2019, respectively)	236,492	224,042
Lease liabilities - operating leases	201,713	200,180
Accounts payable and accrued expenses (amounts related to VIEs of $23,128 and $45,777 at December 31, 2020 and December 31, 2019, respectively)	336,264	377,553
Dividends and distributions payable	171,082	170,713
Accrued interest payable	106,288	90,016
Other liabilities (amounts related to VIEs of $158,805 and $140,110 at December 31, 2020 and December 31, 2019, respectively)	412,084	387,994
Total liabilities	14,511,681	13,262,304
Redeemable deferred stock units— 72,966 and 60,676 units outstanding at redemption value at December 31, 2020 and December 31, 2019, respectively	6,897	8,365
Redeemable partnership units— 16,037,121 and 16,764,466 common units and 1,336,115 and 1,143,215 long term incentive units outstanding at redemption value at December 31, 2020 and December 31, 2019, respectively	1,643,024	2,468,753
Preferred stock, $0.01 par value, 50,000,000 shares authorized;
5.25% Series B cumulative redeemable preferred stock / units, liquidation preference $2,500 per share / unit, 80,000 shares / units issued and outstanding at December 31, 2020 and December 31, 2019, respectively	193,623	193,623
Boston Properties Limited Partnership partners’ capital— 1,730,921 and 1,726,980 general partner units and 153,987,904 and 153,063,318 limited partner units outstanding at December 31, 2020 and December 31, 2019, respectively	4,554,639	3,380,175
Accumulated other comprehensive loss	(49,890)	(48,335)
Total partners’ capital	4,698,372	3,525,463
Noncontrolling interests in property partnerships	1,726,933	1,728,689
Noncontrolling interests:
Total equity / capital	6,425,305	5,254,152
Total liabilities and equity / capital	$ 22,586,907	$ 20,993,574