Brandywine Operating Partnership 10-Q 29 Oct 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Oct. 25, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity Registrant Name	Brandywine Realty Trust
Entity Incorporation, State or Country Code	MD
Entity File Number	001-9106
Entity Tax Identification Number	23-2413352
Entity Address, Address Line One	2929 Arch Street
Entity Address, Address Line Two	Suite 1800
Entity Address, City or Town	Philadelphia
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19104
City Area Code	610
Local Phone Number	325-5600
Title of 12(b) Security	Common Shares of Beneficial Interest
Trading Symbol	BDN
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		171,126,257
Entity Central Index Key	0000790816
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Former Address
Document Information [Line Items]
Entity Address, Address Line One	2929 Walnut Street
Entity Address, Address Line Two	Suite 1700
Entity Address, City or Town	Philadelphia
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19104
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Document Information [Line Items]
Entity Registrant Name	Brandywine Operating Partnership, L.P.
Entity Incorporation, State or Country Code	DE
Entity File Number	000-24407
Entity Tax Identification Number	23-2862640
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001060386

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Real estate investments:
Operating properties	$ 3,437,074	$ 3,474,109
Accumulated depreciation	(957,793)	(896,561)
Right of use asset - operating leases, net	20,478	20,977
Operating real estate investments, net	2,499,759	2,598,525
Construction-in-progress	266,263	210,311
Land held for development	118,684	117,984
Prepaid leasehold interests in land held for development, net	27,762	39,185
Total real estate investments, net	2,912,468	2,966,005
Assets held for sale, net	562	7,349
Cash and cash equivalents	42,484	46,344
Accounts receivable	11,645	13,536
Accrued rent receivable, net of allowance of $4,133 and $5,086 as of September 30, 2021 and December 31, 2020, respectively	165,564	155,372
Investment in unconsolidated real estate ventures	449,658	401,327
Deferred costs, net	81,632	84,856
Intangible assets, net	34,514	48,570
Other assets	131,230	176,747
Total assets	3,829,757	3,900,106
LIABILITIES AND EQUITY
Unsecured term loan, net	249,477	249,084
Unsecured senior notes, net	1,581,112	1,581,511
Accounts payable and accrued expenses	133,615	121,982
Distributions payable	32,763	32,706
Deferred income, gains and rent	21,861	21,396
Intangible liabilities, net	14,451	18,448
Lease liability - operating leases	22,911	22,758
Other liabilities	48,090	47,573
Total liabilities	2,104,280	2,095,458
Commitments and contingencies (See Note 15)
Equity:
Common Shares of Brandywine Realty Trust's beneficial interest, $0.01 par value; shares authorized 400,000,000; 171,126,257 and 170,572,964 issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	1,712	1,707
Additional paid-in-capital	3,145,209	3,138,152
Deferred compensation payable in common shares	18,491	17,516
Common shares in grantor trust, 1,169,703 and 1,160,494 issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	(18,491)	(17,516)
Cumulative earnings	1,117,804	1,110,083
Accumulated other comprehensive loss	(4,333)	(7,561)
Cumulative distributions	(2,545,979)	(2,448,238)
Total Brandywine Realty Trust's equity	1,714,413	1,794,143
Noncontrolling interests	11,064	10,505
Total beneficiaries' equity	1,725,477	1,804,648
Total liabilities and beneficiaries' equity	3,829,757	3,900,106
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Operating properties	3,437,074	3,474,109
Accumulated depreciation	(957,793)	(896,561)
Right of use asset - operating leases, net	20,478	20,977
Operating real estate investments, net	2,499,759	2,598,525
Construction-in-progress	266,263	210,311
Land held for development	118,684	117,984
Prepaid leasehold interests in land held for development, net	27,762	39,185
Total real estate investments, net	2,912,468	2,966,005
Assets held for sale, net	562	7,349
Cash and cash equivalents	42,484	46,344
Accounts receivable	11,645	13,536
Accrued rent receivable, net of allowance of $4,133 and $5,086 as of September 30, 2021 and December 31, 2020, respectively	165,564	155,372
Investment in unconsolidated real estate ventures	449,658	401,327
Deferred costs, net	81,632	84,856
Intangible assets, net	34,514	48,570
Other assets	131,230	176,747
Total assets	3,829,757	3,900,106
LIABILITIES AND EQUITY
Unsecured term loan, net	249,477	249,084
Unsecured senior notes, net	1,581,112	1,581,511
Accounts payable and accrued expenses	133,615	121,982
Distributions payable	32,763	32,706
Deferred income, gains and rent	21,861	21,396
Intangible liabilities, net	14,451	18,448
Lease liability - operating leases	22,911	22,758
Other liabilities	48,090	47,573
Total liabilities	2,104,280	2,095,458
Commitments and contingencies (See Note 15)
Redeemable limited partnership units at redemption value; 823,983 and 981,634 issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	11,170	11,566
Equity:
General Partnership Capital; 171,126,257 and 170,572,964 units issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	1,718,929	1,800,945
Accumulated other comprehensive loss	(4,690)	(7,935)
Total Brandywine Operating Partnership, L.P.'s equity	1,714,239	1,793,010
Noncontrolling interest - consolidated real estate ventures	68	72
Total partners' equity	1,714,307	1,793,082
Total liabilities and beneficiaries' equity	$ 3,829,757	$ 3,900,106

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accrued rent receivable, allowance	$ 4,133	$ 5,086
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	171,126,257	170,572,964
Common stock, shares outstanding (in shares)	171,126,257	170,572,964
Common shares in grantor trust, issued and outstanding (in shares)	1,169,703	1,160,494
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Accrued rent receivable, allowance	$ 4,133	$ 5,086
Redeemable limited partnership units issued (in units)	823,983	981,634
Redeemable limited partnership units outstanding (in units)	823,983	981,634
General partners' capital account, units issued (in units)	171,126,257	170,572,964
General partners' capital account, units outstanding (in units)	171,126,257	170,572,964

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue
Revenue	$ 120,418	$ 126,106	$ 361,289	$ 408,031
Operating expenses
Property operating expenses	30,304	31,567	88,503	102,320
Real estate taxes	13,421	14,923	42,784	48,525
Third party management expenses	3,327	2,509	9,866	7,546
Depreciation and amortization	48,175	43,533	131,303	145,314
General and administrative expenses	7,076	7,069	22,016	23,973
Total operating expenses	102,303	99,601	294,472	327,678
Gain on sale of real estate
Net gain on disposition of real estate	0	271,901	142	274,487
Net gain on sale of undepreciated real estate	910	0	2,903	201
Total gain on sale of real estate	910	271,901	3,045	274,688
Operating income	19,025	298,406	69,862	355,041
Other income (expense):
Interest and investment income	4,494	467	7,845	1,487
Interest expense	(15,190)	(16,310)	(46,973)	(56,510)
Interest expense - amortization of deferred financing costs	(709)	(715)	(2,127)	(2,195)
Equity in loss of unconsolidated real estate ventures	(6,634)	(5,788)	(20,798)	(9,882)
Net gain on real estate venture transactions	0	75	0	75
Net income before income taxes	986	276,135	7,809	288,016
Income tax (provision) benefit	(12)	(2)	(46)	224
Net income	974	276,133	7,763	288,240
Net income attributable to noncontrolling interests	(7)	(1,612)	(42)	(1,701)
Net income attributable to Brandywine Realty Trust	967	274,521	7,721	286,539
Nonforfeitable dividends allocated to unvested restricted shareholders	(91)	(93)	(331)	(317)
Net income attributable to Common Shareholders of Brandywine Realty Trust	$ 876	$ 274,428	$ 7,390	$ 286,222
Basic income per Common Share (in dollars per share)	$ 0.01	$ 1.61	$ 0.04	$ 1.66
Diluted income per Common Share (in dollars per share)	$ 0.01	$ 1.60	$ 0.04	$ 1.66
Basic weighted average shares outstanding (in shares)	170,907,018	170,573,028	170,794,585	172,380,410
Diluted weighted average shares outstanding (in shares)	172,237,194	171,026,492	172,077,950	172,735,436
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Revenue	$ 120,418	$ 126,106	$ 361,289	$ 408,031
Operating expenses
Property operating expenses	30,304	31,567	88,503	102,320
Real estate taxes	13,421	14,923	42,784	48,525
Third party management expenses	3,327	2,509	9,866	7,546
Depreciation and amortization	48,175	43,533	131,303	145,314
General and administrative expenses	7,076	7,069	22,016	23,973
Total operating expenses	102,303	99,601	294,472	327,678
Gain on sale of real estate
Net gain on disposition of real estate	0	271,901	142	274,487
Net gain on sale of undepreciated real estate	910	0	2,903	201
Total gain on sale of real estate	910	271,901	3,045	274,688
Operating income	19,025	298,406	69,862	355,041
Other income (expense):
Interest and investment income	4,494	467	7,845	1,487
Interest expense	(15,190)	(16,310)	(46,973)	(56,510)
Interest expense - amortization of deferred financing costs	(709)	(715)	(2,127)	(2,195)
Equity in loss of unconsolidated real estate ventures	(6,634)	(5,788)	(20,798)	(9,882)
Net gain on real estate venture transactions	0	75	0	75
Net income before income taxes	986	276,135	7,809	288,016
Income tax (provision) benefit	(12)	(2)	(46)	224
Net income	974	276,133	7,763	288,240
Net (income) loss attributable to noncontrolling interests - consolidated real estate ventures	2	2	4	(20)
Net income attributable to Brandywine Operating Partnership	976	276,135	7,767	288,220
Nonforfeitable dividends allocated to unvested restricted shareholders	(91)	(93)	(331)	(317)
Net income attributable to Common Shareholders of Brandywine Realty Trust	$ 885	$ 276,042	$ 7,436	$ 287,903
Basic income per Common Share (in dollars per share)	$ 0.01	$ 1.61	$ 0.04	$ 1.66
Diluted income per Common Share (in dollars per share)	$ 0.01	$ 1.60	$ 0.04	$ 1.66
Basic weighted average shares outstanding (in shares)	171,731,001	171,554,662	171,710,387	173,362,044
Diluted weighted average shares outstanding (in shares)	173,061,177	172,008,126	172,993,752	173,717,070
Rents
Revenue
Revenue	$ 112,159	$ 121,277	$ 336,878	$ 392,661
Rents | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Revenue	112,159	121,277	336,878	392,661
Third party management fees, labor reimbursement and leasing
Revenue
Revenue	6,500	4,324	19,778	13,339
Third party management fees, labor reimbursement and leasing | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Revenue	6,500	4,324	19,778	13,339
Other
Revenue
Revenue	1,759	505	4,633	2,031
Other | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Revenue	$ 1,759	$ 505	$ 4,633	$ 2,031

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net income		$ 974	$ 276,133	$ 7,763	$ 288,240
Comprehensive income (loss):
Unrealized gain (loss) on derivative financial instruments		911	1,040	2,681	(6,979)
Amortization of interest rate contracts	[1]	188	188	564	564
Total comprehensive income (loss)		1,099	1,228	3,245	(6,415)
Comprehensive income		2,073	277,361	11,008	281,825
Comprehensive (income) loss attributable to noncontrolling interest - consolidated real estate ventures		(12)	(1,619)	(59)	(1,665)
Comprehensive income attributable to Brandywine Realty Trust		2,061	275,742	10,949	280,160
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Net income		974	276,133	7,763	288,240
Comprehensive income (loss):
Unrealized gain (loss) on derivative financial instruments		911	1,040	2,681	(6,979)
Amortization of interest rate contracts	[1]	188	188	564	564
Total comprehensive income (loss)		1,099	1,228	3,245	(6,415)
Comprehensive income		2,073	277,361	11,008	281,825
Comprehensive (income) loss attributable to noncontrolling interest - consolidated real estate ventures		2	2	4	(20)
Comprehensive income attributable to Brandywine Realty Trust		$ 2,075	$ 277,363	$ 11,012	$ 281,805
[1]	Amounts reclassified from comprehensive income to interest expense within the Consolidated Statements of Operations.

Consolidated Statements of Bene

Consolidated Statements of Beneficiaries' Equity - USD ($) $ in Thousands	Total	Common Stock	Rabbi Trust/Deferred Compensation Shares	Additional Paid-in Capital	Common Shares in Grantor Trust	Cumulative Earnings	Accumulated Other Comprehensive Income (Loss)	Cumulative Distributions	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2019		176,480,095	1,105,542
Beginning balance at Dec. 31, 2019	$ 1,688,303	$ 1,766	$ 16,216	$ 3,192,158	$ (16,216)	$ 804,556	$ (2,370)	$ (2,318,233)	$ 10,426
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	8,087					8,022			65
Other comprehensive income (loss)	(7,869)						(7,825)		(44)
Repurchase and retirement of Common Shares of Beneficial Interest (in shares)		(5,644,200)
Repurchase and retirement of Common Shares of Beneficial Interest	(53,858)	$ (57)		(53,801)
Share-based compensation activity (in shares)		142,468	50,967
Share-based compensation activity	2,031	$ 1		2,030
Share Issuance from/(to) Deferred Compensation Plan (in shares)		(12,376)	(38,726)
Share Issuance from/(to) Deferred Compensation Plan	(193)		$ 796	(193)	(796)
Distributions declared	(32,687)							(32,500)	(187)
Ending balance (in shares) at Mar. 31, 2020		170,965,987	1,117,783
Ending balance at Mar. 31, 2020	1,603,814	$ 1,710	$ 17,012	3,140,194	(17,012)	812,578	(10,195)	(2,350,733)	10,260
Beginning balance (in shares) at Dec. 31, 2019		176,480,095	1,105,542
Beginning balance at Dec. 31, 2019	1,688,303	$ 1,766	$ 16,216	3,192,158	(16,216)	804,556	(2,370)	(2,318,233)	10,426
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	288,240
Other comprehensive income (loss)	$ (6,415)
Repurchase and retirement of Common Shares of Beneficial Interest (in shares)	(6,248,483)
Repurchase and retirement of Common Shares of Beneficial Interest	$ (60,000)
Ending balance (in shares) at Sep. 30, 2020		170,572,964	1,160,494
Ending balance at Sep. 30, 2020	1,815,782	$ 1,707	$ 17,516	3,136,851	(17,516)	1,091,095	(8,749)	(2,415,736)	10,614
Beginning balance (in shares) at Mar. 31, 2020		170,965,987	1,117,783
Beginning balance at Mar. 31, 2020	1,603,814	$ 1,710	$ 17,012	3,140,194	(17,012)	812,578	(10,195)	(2,350,733)	10,260
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	4,020					3,996			24
Other comprehensive income (loss)	226						225		1
Repurchase and retirement of Common Shares of Beneficial Interest (in shares)		(604,283)
Repurchase and retirement of Common Shares of Beneficial Interest	(6,141)	$ (5)		(6,136)
Share-based compensation activity (in shares)		166,628
Share-based compensation activity	1,668	$ 2		1,666
Share Issuance from/(to) Deferred Compensation Plan (in shares)		44,827	42,906
Share Issuance from/(to) Deferred Compensation Plan	(11)		$ 504	(11)	(504)
Reallocation of Noncontrolling interest	0			(123)					123
Distributions declared	(32,727)							(32,540)	(187)
Ending balance (in shares) at Jun. 30, 2020		170,573,159	1,160,689
Ending balance at Jun. 30, 2020	1,570,849	$ 1,707	$ 17,516	3,135,590	(17,516)	816,574	(9,970)	(2,383,273)	10,221
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	276,133					274,521			1,612
Other comprehensive income (loss)	1,228						1,221		7
Impact of deconsolidation of real estate venture	(1,017)								(1,017)
Distributions from consolidated real estate ventures	(22)								(22)
Share-based compensation activity	1,263			1,263
Share Issuance from/(to) Deferred Compensation Plan (in shares)		(195)	(195)
Share Issuance from/(to) Deferred Compensation Plan	(2)			(2)
Distributions declared	(32,650)							(32,463)	(187)
Ending balance (in shares) at Sep. 30, 2020		170,572,964	1,160,494
Ending balance at Sep. 30, 2020	1,815,782	$ 1,707	$ 17,516	3,136,851	(17,516)	1,091,095	(8,749)	(2,415,736)	10,614
Beginning balance (in shares) at Dec. 31, 2020		170,572,964	1,160,494
Beginning balance at Dec. 31, 2020	1,804,648	$ 1,707	$ 17,516	3,138,152	(17,516)	1,110,083	(7,561)	(2,448,238)	10,505
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	6,964					6,921			43
Other comprehensive income (loss)	1,098						1,092		6
Share-based compensation activity (in shares)		108,345	12,719
Share-based compensation activity	2,502			2,502
Share Issuance from/(to) Deferred Compensation Plan (in shares)		(18,058)	(61,436)
Share Issuance from/(to) Deferred Compensation Plan	(198)		$ 142	(198)	(142)
Distributions declared	(32,760)							(32,573)	(187)
Ending balance (in shares) at Mar. 31, 2021		170,663,251	1,111,777
Ending balance at Mar. 31, 2021	1,782,254	$ 1,707	$ 17,658	3,140,456	(17,658)	1,117,004	(6,469)	(2,480,811)	10,367
Beginning balance (in shares) at Dec. 31, 2020		170,572,964	1,160,494
Beginning balance at Dec. 31, 2020	1,804,648	$ 1,707	$ 17,516	3,138,152	(17,516)	1,110,083	(7,561)	(2,448,238)	10,505
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	7,763
Other comprehensive income (loss)	$ 3,245
Repurchase and retirement of Common Shares of Beneficial Interest (in shares)	0
Ending balance (in shares) at Sep. 30, 2021		171,126,257	1,169,703
Ending balance at Sep. 30, 2021	$ 1,725,477	$ 1,712	$ 18,491	3,145,209	(18,491)	1,117,804	(4,333)	(2,545,979)	11,064
Beginning balance (in shares) at Mar. 31, 2021		170,663,251	1,111,777
Beginning balance at Mar. 31, 2021	1,782,254	$ 1,707	$ 17,658	3,140,456	(17,658)	1,117,004	(6,469)	(2,480,811)	10,367
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(175)					(167)			(8)
Other comprehensive income (loss)	1,048						1,042		6
Issuance of partnership interest in consolidated real estate ventures	2,289								2,289
Redemption of LP Units	(2,334)								(2,334)
Share-based compensation activity (in shares)		237,240	63,566
Share-based compensation activity	690	$ 2		688
Share Issuance from/(to) Deferred Compensation Plan	0		$ 833		(833)
Reallocation of Noncontrolling interest	0			(569)					569
Distributions declared	(32,719)							(32,562)	(157)
Ending balance (in shares) at Jun. 30, 2021		170,900,491	1,175,343
Ending balance at Jun. 30, 2021	1,751,053	$ 1,709	$ 18,491	3,140,575	(18,491)	1,116,837	(5,427)	(2,513,373)	10,732
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	974					967			7
Other comprehensive income (loss)	1,099						1,094		5
Issuance of Common Shares of Beneficial Interest (in shares)		226,695
Issuance of Common Shares of Beneficial Interest	3,052	$ 3		3,049
Issuance of partnership interest in consolidated real estate ventures	476								476
Share-based compensation activity (in shares)		(929)	(5,640)
Share-based compensation activity	1,585			1,585
Distributions declared	(32,762)							(32,606)	(156)
Ending balance (in shares) at Sep. 30, 2021		171,126,257	1,169,703
Ending balance at Sep. 30, 2021	$ 1,725,477	$ 1,712	$ 18,491	$ 3,145,209	$ (18,491)	$ 1,117,804	$ (4,333)	$ (2,545,979)	$ 11,064

Consolidated Statements of Be_2

Consolidated Statements of Beneficiaries' Equity (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Distributions declared (in dollars per share)	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19

Consolidated Statements of Part

Consolidated Statements of Partners' Equity - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest - Consolidated Real Estate Ventures	BRANDYWINE OPERATING PARTNERSHIP, L.P.	BRANDYWINE OPERATING PARTNERSHIP, L.P.Accumulated Other Comprehensive Income (Loss)	BRANDYWINE OPERATING PARTNERSHIP, L.P.Noncontrolling Interest - Consolidated Real Estate Ventures	BRANDYWINE OPERATING PARTNERSHIP, L.P.General Partner Capital
Beginning balance (in shares) at Dec. 31, 2019							176,480,095
Beginning Balance at Dec. 31, 2019				$ 1,672,915	$ (2,715)	$ 1,091	$ 1,674,539
Net income (loss)	$ 8,087		$ 65	8,087		12	$ 8,075
Other comprehensive income (loss)	(7,869)	$ (7,825)	(44)	(7,869)	(7,869)
Deferred compensation obligation (in shares)							(12,376)
Deferred compensation obligation	(193)			(193)			$ (193)
Repurchase and retirement of LP units (in shares)							(5,644,200)
Repurchase and retirement of LP units				(53,858)			$ (53,858)
Share-based compensation activity (in shares)							142,468
Share-based compensation activity	2,031			2,031			$ 2,031
Adjustment of redeemable partnership units to liquidation value at period end				5,220			5,220
Distributions declared to general partnership unitholders				(32,500)			$ (32,500)
Ending balance (in shares) at Mar. 31, 2020							170,965,987
Ending Balance at Mar. 31, 2020				1,593,833	(10,584)	1,103	$ 1,603,314
Beginning balance (in shares) at Dec. 31, 2019							176,480,095
Beginning Balance at Dec. 31, 2019				1,672,915	(2,715)	1,091	$ 1,674,539
Net income (loss)	288,240			288,240
Other comprehensive income (loss)	(6,415)			(6,415)
Ending balance (in shares) at Sep. 30, 2020							170,572,964
Ending Balance at Sep. 30, 2020				1,805,832	(9,130)	72	$ 1,814,890
Beginning balance (in shares) at Mar. 31, 2020							170,965,987
Beginning Balance at Mar. 31, 2020				1,593,833	(10,584)	1,103	$ 1,603,314
Net income (loss)	4,020		24	4,020		10	$ 4,010
Other comprehensive income (loss)	226	225	1	226	226
Deferred compensation obligation (in shares)							(44,827)
Deferred compensation obligation	(11)			(11)			$ (11)
Repurchase and retirement of LP units (in shares)							(604,283)
Repurchase and retirement of LP units				(6,141)			$ (6,141)
Share-based compensation activity (in shares)							166,628
Share-based compensation activity	1,668			1,668			$ 1,668
Adjustment of redeemable partnership units to liquidation value at period end				(743)			(743)
Distributions declared to general partnership unitholders				(32,540)			$ (32,540)
Ending balance (in shares) at Jun. 30, 2020							170,573,159
Ending Balance at Jun. 30, 2020				1,560,312	(10,358)	1,113	$ 1,569,557
Net income (loss)	276,133		1,612	276,133		(2)	$ 276,135
Other comprehensive income (loss)	1,228	1,221	7	1,228	1,228
Deferred compensation obligation (in shares)							(195)
Deferred compensation obligation	(2)			(2)			$ (2)
Distributions from consolidated real estate ventures	(22)		(22)	(22)		(22)
Share-based compensation activity	1,263			1,263			1,263
Impact of deconsolidation of real estate venture	(1,017)		(1,017)	(1,017)		(1,017)
Adjustment of redeemable partnership units to liquidation value at period end				400			400
Distributions declared to general partnership unitholders				(32,463)			$ (32,463)
Ending balance (in shares) at Sep. 30, 2020							170,572,964
Ending Balance at Sep. 30, 2020				1,805,832	(9,130)	72	$ 1,814,890
Beginning balance (in shares) at Dec. 31, 2020							170,572,964
Beginning Balance at Dec. 31, 2020				1,793,082	(7,935)	72	$ 1,800,945
Net income (loss)	6,964		43	6,964		(1)	$ 6,965
Other comprehensive income (loss)	1,098	1,092	6	1,098	1,098
Deferred compensation obligation (in shares)							(18,058)
Deferred compensation obligation	(198)			(198)			$ (198)
Share-based compensation activity (in shares)							108,345
Share-based compensation activity	2,502			2,502			$ 2,502
Adjustment of redeemable partnership units to liquidation value at period end				(1,294)			(1,294)
Distributions declared to general partnership unitholders				(32,573)			$ (32,573)
Ending balance (in shares) at Mar. 31, 2021							170,663,251
Ending Balance at Mar. 31, 2021				1,769,581	(6,837)	71	$ 1,776,347
Beginning balance (in shares) at Dec. 31, 2020							170,572,964
Beginning Balance at Dec. 31, 2020				1,793,082	(7,935)	72	$ 1,800,945
Net income (loss)	7,763			7,763
Other comprehensive income (loss)	3,245			3,245
Ending balance (in shares) at Sep. 30, 2021							171,126,257
Ending Balance at Sep. 30, 2021				1,714,307	(4,690)	68	$ 1,718,929
Beginning balance (in shares) at Mar. 31, 2021							170,663,251
Beginning Balance at Mar. 31, 2021				1,769,581	(6,837)	71	$ 1,776,347
Net income (loss)	(175)		(8)	(175)		(1)	(174)
Other comprehensive income (loss)	1,048	1,042	6	1,048	1,048
Deferred compensation obligation	0
Repurchase and retirement of LP units				(2,334)			(2,334)
Issuance of partnership interest in consolidated real estate ventures	2,289		2,289	2,289			$ 2,289
Share-based compensation activity (in shares)							237,240
Share-based compensation activity	690			690			$ 690
Adjustment of redeemable partnership units to liquidation value at period end				1,066			1,066
Distributions declared to general partnership unitholders				(32,562)			$ (32,562)
Ending balance (in shares) at Jun. 30, 2021							170,900,491
Ending Balance at Jun. 30, 2021				1,739,603	(5,789)	70	$ 1,745,322
Net income (loss)	974		7	974		(2)	$ 976
Other comprehensive income (loss)	1,099	$ 1,094	5	1,099	1,099
Issuance of LP Units (in shares)							226,695
Issuance of LP Units	3,052						$ 3,052
Issuance of partnership interest in consolidated real estate ventures	476		$ 476	476			$ 476
Share-based compensation activity (in shares)							(929)
Share-based compensation activity	$ 1,585			1,585			$ 1,585
Adjustment of redeemable partnership units to liquidation value at period end				124			124
Distributions declared to general partnership unitholders				(32,606)			$ (32,606)
Ending balance (in shares) at Sep. 30, 2021							171,126,257
Ending Balance at Sep. 30, 2021				$ 1,714,307	$ (4,690)	$ 68	$ 1,718,929

Consolidated Statements of Pa_2

Consolidated Statements of Partners' Equity (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
BRANDYWINE OPERATING PARTNERSHIP, L.P. | General Partner Capital
Distributions to general partnership unitholders (USD per share)	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net income	$ 7,763	$ 288,240
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	131,303	145,314
Amortization of deferred financing costs	2,127	2,195
Amortization of debt discount/(premium), net	(1,463)	(55)
Amortization of stock compensation costs	5,732	5,544
Straight-line rent income	(10,641)	(8,903)
Amortization of acquired above (below) market leases, net	(3,929)	(3,657)
Ground rent expense	712	1,092
Provision for doubtful accounts	940	1,041
Net gain on sale of interests in real estate	(3,045)	(274,688)
Loss from unconsolidated real estate ventures, net of distributions	20,798	9,880
Income tax provision (benefit)	46	(224)
Changes in assets and liabilities:
Accounts receivable	672	(6,263)
Other assets	(8,562)	(7,527)
Accounts payable and accrued expenses	3,650	10,782
Deferred income, gains and rent	914	(8,856)
Other liabilities	(6,298)	8,549
Net cash provided by operating activities	140,719	162,464
Cash flows from investing activities:
Acquisition of properties	0	(11,432)
Proceeds from the sale of properties	10,303	122,055
Proceeds from insurance	1,250	0
Proceeds from note receivable	50,000	0
Capital expenditures for tenant improvements	(30,168)	(55,262)
Capital expenditures for redevelopments	(18,705)	(18,664)
Capital expenditures for developments	(26,694)	(51,435)
Advances for the purchase of tenant assets, net of repayments	279	1,265
Investment in unconsolidated real estate ventures	(27,210)	(719)
Capital distributions from unconsolidated real estate ventures	7,499	6,916
Leasing costs paid	(11,475)	(16,747)
Net cash used in investing activities	(44,921)	(24,023)
Cash flows from financing activities:
Repayments of mortgage notes payable	0	(6,105)
Proceeds from credit facility borrowings	116,000	170,500
Repayments of credit facility borrowings	(116,000)	(170,500)
Exercise of stock options, net	(63)	47
Shares used for employee taxes upon vesting of share awards	(1,762)	(1,346)
Partner contributions to consolidated real estate venture	2,765	0
Repurchase and retirement of common shares	0	(60,000)
Redemption of limited partnership units	(2,334)	0
Distributions paid to shareholders	(97,637)	(98,651)
Distributions to noncontrolling interest	(547)	(561)
Net cash used in financing activities	(99,578)	(166,616)
Decrease in cash and cash equivalents and restricted cash	(3,780)	(28,175)
Cash and cash equivalents and restricted cash at beginning of period	47,077	91,170
Cash and cash equivalents and restricted cash at end of period	43,297	62,995
Reconciliation of cash and cash equivalents and restricted cash:
Cash and cash equivalents, beginning of period	46,344	90,499
Restricted cash, beginning of period	733	671
Cash and cash equivalents and restricted cash at beginning of period	47,077	91,170
Cash and cash equivalents, end of period	42,484	62,256
Restricted cash, end of period	813	739
Cash and cash equivalents and restricted cash at end of period	43,297	62,995
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the nine months ended September 30, 2021 and 2020 of $6,348 and $3,462, respectively	45,786	51,733
Cash paid for income taxes	23	719
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	32,763	32,705
Change in investment in real estate ventures as a result of dispositions	32,761	0
Change in operating real estate from deconsolidation of operating properties	(30,073)	269,268
Change in investment in real estate ventures from deconsolidation of operating properties	0	(263,358)
Change in mortgage notes payable from deconsolidation of operating properties	0	(220,271)
Change in other assets as a result of deconsolidation of operating properties	(2,688)	0
Change in capital expenditures financed through accounts payable at period end	6,653	(8,244)
Change in capital expenditures financed through retention payable at period end	(1,473)	754
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Cash flows from operating activities:
Net income	7,763	288,240
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	131,303	145,314
Amortization of deferred financing costs	2,127	2,195
Amortization of debt discount/(premium), net	(1,463)	(55)
Amortization of stock compensation costs	5,732	5,544
Straight-line rent income	(10,641)	(8,903)
Amortization of acquired above (below) market leases, net	(3,929)	(3,657)
Ground rent expense	712	1,092
Provision for doubtful accounts	940	1,041
Net gain on sale of interests in real estate	(3,045)	(274,688)
Loss from unconsolidated real estate ventures, net of distributions	20,798	9,880
Income tax provision (benefit)	46	(224)
Changes in assets and liabilities:
Accounts receivable	672	(6,263)
Other assets	(8,562)	(7,527)
Accounts payable and accrued expenses	3,650	10,782
Deferred income, gains and rent	914	(8,856)
Other liabilities	(6,298)	8,549
Net cash provided by operating activities	140,719	162,464
Cash flows from investing activities:
Acquisition of properties	0	(11,432)
Proceeds from the sale of properties	10,303	122,055
Proceeds from insurance	1,250	0
Proceeds from note receivable	50,000	0
Capital expenditures for tenant improvements	(30,168)	(55,262)
Capital expenditures for redevelopments	(18,705)	(18,664)
Capital expenditures for developments	(26,694)	(51,435)
Advances for the purchase of tenant assets, net of repayments	279	1,265
Investment in unconsolidated real estate ventures	(27,210)	(719)
Capital distributions from unconsolidated real estate ventures	7,499	6,916
Leasing costs paid	(11,475)	(16,747)
Net cash used in investing activities	(44,921)	(24,023)
Cash flows from financing activities:
Repayments of mortgage notes payable	0	(6,105)
Proceeds from credit facility borrowings	116,000	170,500
Repayments of credit facility borrowings	(116,000)	(170,500)
Exercise of stock options, net	(63)	47
Shares used for employee taxes upon vesting of share awards	(1,762)	(1,346)
Partner contributions to consolidated real estate venture	2,765	0
Repurchase and retirement of common shares	0	(60,000)
Redemption of limited partnership units	(2,334)	0
Distributions paid to shareholders	(98,184)	(99,212)
Net cash used in financing activities	(99,578)	(166,616)
Decrease in cash and cash equivalents and restricted cash	(3,780)	(28,175)
Cash and cash equivalents and restricted cash at beginning of period	47,077	91,170
Cash and cash equivalents and restricted cash at end of period	43,297	62,995
Reconciliation of cash and cash equivalents and restricted cash:
Cash and cash equivalents, beginning of period	46,344	90,499
Restricted cash, beginning of period	733	671
Cash and cash equivalents and restricted cash at beginning of period	47,077	91,170
Cash and cash equivalents, end of period	42,484	62,256
Restricted cash, end of period	813	739
Cash and cash equivalents and restricted cash at end of period	43,297	62,995
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the nine months ended September 30, 2021 and 2020 of $6,348 and $3,462, respectively	45,786	51,733
Cash paid for income taxes	23	719
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	32,763	32,705
Change in investment in real estate ventures as a result of dispositions	32,761	0
Change in operating real estate from deconsolidation of operating properties	(30,073)	269,268
Change in investment in real estate ventures from deconsolidation of operating properties	0	(263,358)
Change in mortgage notes payable from deconsolidation of operating properties	0	(220,271)
Change in other assets as a result of deconsolidation of operating properties	(2,688)	0
Change in capital expenditures financed through accounts payable at period end	6,653	(8,244)
Change in capital expenditures financed through retention payable at period end	$ (1,473)	$ 754

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Capitalized interest	$ 6,348	$ 3,462
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Capitalized interest	$ 6,348	$ 3,462

Organization of the Parent Comp

Organization of the Parent Company and The Operating Partnership	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION OF THE PARENT COMPANY AND THE OPERATING PARTNERSHIP	1. ORGANIZATION OF THE PARENT COMPANY AND THE OPERATING PARTNERSHIP Brandywine Realty Trust (the "Parent Company") is a self-administered and self-managed real estate investment trust (“REIT”) engaged in the acquisition, development, redevelopment, ownership, management, and operation of a portfolio of office and mixed-use properties. The Parent Company owns its assets and conducts its operations through Brandywine Operating Partnership, L.P. (the "Operating Partnership") and subsidiaries of the Operating Partnership. The Parent Company is the sole general partner of the Operating Partnership and, as of September 30, 2021, owned a 99.5% interest in the Operating Partnership. The Parent Company’s common shares of beneficial interest are publicly traded on the New York Stock Exchange under the ticker symbol “BDN”. The Parent Company, the Operating Partnership, and their consolidated subsidiaries are collectively referred to as the "Company". As of September 30, 2021, the Company owned 81 properties that contained an aggregate of approximately 13.7 million net rentable square feet (collectively, the “Properties”). The Company’s core portfolio of operating properties (the “Core Properties”) excludes development properties, redevelopment properties, and properties held for sale. The Properties were comprised of the following as of September 30, 2021: Number of Properties Rentable Square Feet Office properties 71 12,006,744 Mixed-use properties 5 942,334 Core Properties 76 12,949,078 Development property 1 205,803 Redevelopment properties 4 496,769 The Properties 81 13,651,650 In addition to the Properties, as of September 30, 2021, the Company owned 176.1 acres of land held for development, of which 10.0 acres were held for sale. The Company also held a leasehold interest in one land parcel totaling 0.8 acres, acquired through a prepaid 99-year ground lease, and held options to purchase approximately 55.5 additional acres of undeveloped land. As of September 30, 2021, the total potential development that this inventory of land could support under current zoning and entitlements, including the parcels under option, amounted to an estimated 13.4 million square feet of which 0.1 million square feet relates to 10.0 acres held for sale. As of September 30, 2021, the Company also owned economic interests in ten unconsolidated real estate ventures (see Note 4, ''Investment in Unconsolidated Real Estate Ventures” for further information). The Properties and the properties owned by the unconsolidated real estate ventures are primarily located in or near Philadelphia, Pennsylvania; Austin, Texas; Metropolitan Washington, D.C.; Southern New Jersey; and Wilmington, Delaware. The Company conducts its third-party real estate management services business primarily through wholly-owned management company subsidiaries. As of September 30, 2021, the management company subsidiaries were managing properties containing an aggregate of approximately 24.4 million net rentable square feet, of which approximately 13.7 million net rentable square feet related to Properties owned by the Company and approximately 10.7 million net rentable square feet related to properties owned by third parties and unconsolidated real estate ventures. Unless otherwise indicated, all references in this Form 10-Q to square feet represent net rentable area.

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
BASIS OF PRESENTATION	2. BASIS OF PRESENTATION Basis of Presentation The consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, all adjustments consist solely of normal recurring matters, and result in a fair statement of the financial position of the Company as of September 30, 2021, the results of its operations for the three and nine months ended September 30, 2021 and 2020 and its cash flows for the nine months ended September 30, 2021 and 2020. The results of operations for such interim periods are not necessarily indicative of the results for a full year. These consolidated financial statements should be read in conjunction with the Parent Company’s and the Operating Partnership’s consolidated financial statements and footnotes included in their combined Annual Report on Form 10-K for the year ended December 31, 2020 filed with the SEC on February 24, 2021. The consolidated balance sheet at December 31, 2020 has been derived from the audited financial statements as of that date but does not include all the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. The Company's Annual Report on Form 10-K for the year ended December 31, 2020 contains a discussion of its significant accounting policies under Note 2, "Summary of Significant Accounting Policies" . There have been no significant changes in the Company's significant accounting policies since December 31, 2020. Change in Depreciable Lives of Real Estate Investments In accordance with its policy, the Company reviews the estimated useful lives of its real estate investments on an ongoing basis. Pu rsuant to our Broadmoor master development plans, the estimated useful lives of seven properties in Austin, Texas were modified to reflect the estimated periods during which these assets will remain in service. The estimated useful lives of the properties that were approximately 35 years were decreased to approximately 12 years. The effect of this change in estimate was a $3.3 million and $6.5 million increase in depreciation expense during the three and nine months ended September 30, 2021, respectively. Recent Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04 Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting. The amendments provide practical expedients for reference rate reform related activities that impact debt, leases, derivatives and other contracts. The guidance is optional and is effective between March 12, 2020 and December 31, 2022. The guidance may be elected over time as reference rate reform activities occur. The Company continues to evaluate the impact of the guidance and may apply elections as applicable as additional changes in the market occur.

Real Estate Investments

Real Estate Investments	9 Months Ended
	Sep. 30, 2021
Real Estate [Abstract]
REAL ESTATE INVESTMENTS	3. REAL ESTATE INVESTMENTS As of September 30, 2021 and December 31, 2020, the gross carrying value of the operating properties was as follows (in thousands): September 30, 2021 December 31, 2020 Land $ 391,261 $ 407,514 Building and improvements 2,640,229 2,665,232 Tenant improvements 405,584 401,363 Total $ 3,437,074 $ 3,474,109 Dispositions The following table summarizes the property dispositions during the nine months ended September 30, 2021 (dollars in thousands): Property/Portfolio Name Disposition Date Location Property Type Rentable Square Feet/Acres Sales Price Gain/(Loss) on Sale (a) 2100-2200 Lenox Drive July 6, 2021 Lawrenceville, NJ Land 35.2 acres $ 8,900 $ 842 1100 Lenox Drive September 8, 2021 Lawrenceville, NJ Land 5.0 acres $ 2,575 $ 68 (a) Gain/(Loss) on Sale is net of closing and other transaction related costs. In addition, on February 2, 2021, the Company contributed its investment in a 99-year prepaid leasehold interest in a one-acre land parcel held for development at 3025 JFK Boulevard in Philadelphia, Pennsylvania to a newly formed joint venture with an unaffiliated third party. The project is part of the Schuylkill Yards master development. The transaction valued the Company's investment in the project at $34.8 million and resulted in deconsolidation of the property and conversion of Brandywine Opportunity Fund, L.P. to a real estate venture ("3025 JFK Venture"). The Company recorded its investment at fair value and recognized a gain of $2.0 million in "Net gain on sale of undepreciated real estate" on the consolidated statements of operations. See Note 4, "Investment in Unconsolidated Real Estate Ventures," for further information. Held for Sale As of September 30, 2021, the Company determined that the sale of two adjacent parcels of land within the Other segment totaling 10.0 acres was probable and classified these properties as held for sale. As such, $0.6 million was classified as “Assets held for sale, net” on the consolidated balance sheets.

Investment in Unconsolidated Re

Investment in Unconsolidated Real Estate Ventures	9 Months Ended
	Sep. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES	4. INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES As of September 30, 2021, the Company held ownership interests in ten unconsolidated real estate ventures for a net aggregate investment balance of $427.4 million, which includes a negative investment balance in one unconsolidated real estate venture of $22.2 million, reflected within "Other liabilities" on the consolidated balance sheets. As of September 30, 2021, five of the real estate ventures owned properties that contained an aggregate of approximately 8.4 million net rentable square feet of office space; two real estate ventures owned 1.4 acres of land held for development; one real estate venture owned 1.0 acres of land in active development; one real estate venture owned a mixed used tower comprised of 250 apartment units and 0.2 million net rentable square feet of office/retail space; and one real estate venture owned a residential tower that contained 321 apartment units. The Company accounts for its interests in the unconsolidated real estate ventures, which range from 15% to 70%, using the equity method. Certain of the unconsolidated real estate ventures are subject to specified priority allocations of distributable cash. The Company earned management fees from the unconsolidated real estate ventures of $2.1 million and $1.3 million for the three months ended September 30, 2021 and 2020, respectively, and $6.2 million and $3.2 million for the nine months ended September 30, 2021 and 2020, respectively. The Company earned leasing commissions from the unconsolidated real estate ventures of $0.7 million and $0.2 million for the three months ended September 30, 2021 and 2020, respectively, and $2.6 million and $0.9 million for the nine months ended September 30, 2021 and 2020, respectively. The Company had outstanding accounts receivable balances from the unconsolidated real estate ventures of $2.0 million and $1.2 million as of September 30, 2021 and December 31, 2020, respectively. The amounts reflected in the following tables (except for the Company’s share of equity in income) are based on the financial information of the individual unconsolidated real estate ventures. The following is a summary of the financial position of the unconsolidated real estate ventures in which the Company held interests as of September 30, 2021 and December 31, 2020 (in thousands): September 30, 2021 December 31, 2020 Net property $ 1,573,569 $ 1,520,804 Other assets 443,610 488,805 Other liabilities 328,446 333,049 Debt, net 954,213 956,688 Equity (a) 734,520 719,872 (a) This amount does not include the effect of the basis difference between the Company's historical cost basis and the basis recorded at the real estate venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from the impairment of investments, purchases of third party interests in existing real estate ventures and upon the transfer of assets that were previously owned by the Company into a real estate venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the real estate venture level. The following is a summary of results of operations of the unconsolidated real estate ventures in which the Company held interests during the three and nine month periods ended September 30, 2021 and 2020 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Revenue $ 53,991 $ 43,109 $ 160,576 $ 105,554 Operating expenses (29,650) (23,870) (87,266) (59,838) Interest expense, net (8,024) (6,175) (23,414) (16,320) Depreciation and amortization (23,038) (22,345) (73,431) (47,493) Provision for impairment (1,125) — (1,125) — Net loss $ (7,846) $ (9,281) $ (24,660) $ (18,097) Ownership interest % Various Various Various Various Company's share of net loss $ (6,572) $ (5,812) $ (20,394) $ (9,892) Basis adjustments and other (62) 24 (404) 10 Equity in loss of unconsolidated real estate ventures $ (6,634) $ (5,788) $ (20,798) $ (9,882) Brandywine - AI Venture During the three months ended September 30, 2021, Brandywine - AI Venture, in which the Company owns a 50% interest, recorded a $1.1 million held for sale impairment charge related to 3141 Fairview Park Drive. The Company’s share of the impairment charge was $0.6 million, which is reflected in “Equity in loss of Real Estate Ventures” in the consolidated statements of operations for the three months ended September 30, 2021. The impairment was measured based on an executed sale agreement with a third-party. The Company determined that its investment in the real estate venture is not impaired as the Company's share of the distributable cash is in excess of the Company's basis in the real estate venture. 3025 JFK Venture On February 2, 2021, the Company contributed its investment in a 99-year prepaid leasehold interest in a one-acre land parcel held for development at 3025 JFK Boulevard in Philadelphia, Pennsylvania to the 3025 JFK Venture. The Company's initial investment in this real estate venture at February 2, 2021 was $34.8 million. The real estate venture was formed to develop a 570,000 square foot mixed-use building at property under the long-term ground lease. The estimated project cost is approximately $287.3 million, and the joint venture partner has agreed, subject to customary funding conditions, to fund up to approximately $45.2 million of the project costs in exchange for a 45% preferred equity interest in the venture and the Company will retain a 55% preferred equity interest. In addition to its $34.8 million credit for contribution of the leasehold interest at 3025 JFK Venture, the Company has funded $20.5 million of project costs as of September 30, 2021. On July 23, 2021, the 3025 JFK Venture closed on a $186.7 million construction loan, which will bear interest at 3.50% plus LIBOR (subject to a LIBOR floor of 0.25%) per annum and matures in July 2025. The Company has determined that the 3025 JFK Venture is a variable interest entity ("VIE"). As a result, the Company used the VIE model under the accounting standard for consolidation in order to determine whether to consolidate the 3025 JFK Venture. Based upon each member’s shared power over the activities of 3025 JFK Venture under the operating and related agreements, and the Company’s lack of control over the development and construction phases of the project, 3025 JFK Venture is accounted for under the equity method of accounting.

Debt and Preferred Equity Inves

Debt and Preferred Equity Investments	9 Months Ended
	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Debt and Preferred Equity Investments	5. DEBT AND PREFERRED EQUITY INVESTMENTS Austin Preferred Equity Investment On December 31, 2020, the Company invested $50.0 million in exchange for a preferred equity interest in a single-purpose entity that owned two stabilized office buildings located in Austin, Texas. The Company accounted for this mandatorily redeemable investment as a note receivable, which was included within “Other assets” on the consolidated balance sheets. The preferred equity interest accrued a 9.0% annual return, compounded and paid monthly. The investment was required to be redeemed no later than December 31, 2023 (subject to a one-year extension option). On September 3, 2021, the $50.0 million investment was redeemed prior to maturity. As a result, the Company recognized an incremental $2.8 million of income on early redemption related to its accelerated minimum return and exit fees paid in cash on the redemption date during the three months ended September 30, 2021, which is included in "Interest and investment income" on the consolidated statements of operations.

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
LEASES	6. LEASES Lessor Accounting The table below sets forth the allocation of lease revenue between fixed contractual payments and variable lease payments for the three and nine months ended September 30, 2021 and 2020 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Lease Revenue 2021 2020 2021 2020 Fixed contractual payments $ 87,498 $ 95,751 $ 259,995 $ 302,146 Variable lease payments 21,265 22,716 67,473 80,824 Total $ 108,763 $ 118,467 $ 327,468 $ 382,970

Intangible Assets and Liabiliti

Intangible Assets and Liabilities	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS AND LIABILITIES	7. INTANGIBLE ASSETS AND LIABILITIES As of September 30, 2021 and December 31, 2020, the Company’s intangible assets/liabilities were comprised of the following (in thousands): September 30, 2021 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 80,630 $ (46,386) $ 34,244 Tenant relationship value 167 (95) 72 Above market leases acquired 486 (288) 198 Total intangible assets, net $ 81,283 $ (46,769) $ 34,514 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 28,881 $ (14,430) $ 14,451 December 31, 2020 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 91,552 $ (43,400) $ 48,152 Tenant relationship value 2,091 (1,938) 153 Above market leases acquired 530 (265) 265 Total intangible assets, net $ 94,173 $ (45,603) $ 48,570 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 31,263 $ (12,815) $ 18,448 As of September 30, 2021, the Company’s annual amortization for its intangible assets/liabilities, assuming no prospective early lease terminations, was as follows (dollars in thousands): Assets Liabilities 2021 (three months remaining) $ 3,711 $ 1,129 2022 9,807 2,645 2023 7,218 1,609 2024 4,993 1,392 2025 3,805 1,115 Thereafter 4,980 6,561 Total $ 34,514 $ 14,451

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
DEBT OBLIGATIONS	8. DEBT OBLIGATIONS The following table sets forth information regarding the Company’s consolidated debt obligations outstanding as of September 30, 2021 and December 31, 2020 (in thousands): September 30, 2021 December 31, 2020 Effective Maturity UNSECURED DEBT $600 million Unsecured Credit Facility $ — $ — LIBOR + 1.10% July 2022 (a) Seven 250,000 250,000 2.87% October 2022 $350.0M 3.95% Guaranteed Notes due 2023 350,000 350,000 3.87% February 2023 $350.0M 4.10% Guaranteed Notes due 2024 350,000 350,000 3.78% October 2024 $450.0M 3.95% Guaranteed Notes due 2027 450,000 450,000 4.03% November 2027 $350.0M 4.55% Guaranteed Notes due 2029 350,000 350,000 4.30% October 2029 Indenture IA (Preferred Trust I) 27,062 27,062 LIBOR + 1.25% March 2035 Indenture IB (Preferred Trust I) 25,774 25,774 LIBOR + 1.25% April 2035 Indenture II (Preferred Trust II) 25,774 25,774 LIBOR + 1.25% July 2035 Principal balance outstanding 1,828,610 1,828,610 Plus: original issue premium (discount), net 8,675 10,137 Less: deferred financing costs (6,696) (8,152) Total unsecured indebtedness $ 1,830,589 $ 1,830,595 (a) The Company has the ability to extend the term of the Unsecured Credit Facility until July 2023 through two successive six-month extension options. The Company utilizes borrowings under its unsecured revolving credit facility (the “Unsecured Credit Facility”) for general business purposes, including to fund costs of acquisitions, developments and redevelopments of properties, fund share repurchases and repay other debt. The Unsecured Credit Facility provides for borrowings of up to $600.0 million and the per annum variable interest rate on borrowings is LIBOR plus 1.10%. The interest rate and facility fee are subject to adjustment upon a change in the Company’s unsecured debt ratings. During the nine months ended September 30, 2021, the weighted-average interest rate on Unsecured Credit Facility borrowings was 1.21% resulting in $0.3 million of interest expense. The Parent Company unconditionally guarantees the unsecured debt obligations of the Operating Partnership (or is a co-borrower with the Operating Partnership) but does not by itself incur unsecured indebtedness. The Parent Company has no material assets other than its investment in the Operating Partnership. The Company was in compliance with all financial covenants as of September 30, 2021. Certain of the covenants restrict the Company’s ability to obtain alternative sources of capital. As of September 30, 2021, the aggregate scheduled principal payments on the Company's debt obligations were as follows (in thousands): 2021 (three months remaining) $ — 2022 250,000 2023 350,000 2024 350,000 2025 — Thereafter 878,610 Total principal payments 1,828,610 Net unamortized premiums/(discounts) 8,675 Net deferred financing costs (6,696) Outstanding indebtedness $ 1,830,589

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	9. FAIR VALUE OF FINANCIAL INSTRUMENTS Financial assets and liabilities recorded on the consolidated balance sheets are categorized based on the inputs to the valuation techniques as follows: • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access; • Level 2 inputs are inputs, other than quoted prices included in Level 1, which are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals; and • Level 3 inputs are unobservable inputs for the asset or liability, which is typically based on an entity’s own assumptions, as there is little, if any, related market activity or information. The Company determined the fair values disclosed below using available market information and discounted cash flow analyses as of September 30, 2021 and December 31, 2020, respectively. The discount rate used in calculating fair value is the sum of the current risk free rate and the risk premium on the date of measurement of the instruments or obligations. Considerable judgment is necessary to interpret market data and to develop the related estimates of fair value. Accordingly, the estimates presented are not necessarily indicative of the amounts that the Company could realize upon disposition. The use of different estimates and valuation methodologies may have a material effect on the fair value amounts shown. The Company believes that the carrying amounts reflected in the consolidated balance sheets at September 30, 2021 and December 31, 2020 approximate the fair values for cash and cash equivalents, accounts receivable, other assets and liabilities, accounts payable and accrued expenses because they are short-term in duration. The following are financial instruments for which the Company’s estimates of fair value differ from the carrying amounts (in thousands): September 30, 2021 December 31, 2020 Carrying Amount (a) Fair Value Carrying Amount (a) Fair Value Unsecured notes payable $ 1,502,502 $ 1,623,840 $ 1,502,901 $ 1,607,310 Variable rate debt $ 328,087 $ 309,523 $ 327,694 $ 308,838 Notes receivable (b) $ 44,430 $ 46,266 $ 94,430 $ 97,372 (a) Net of deferred financing costs of $6.2 million and $7.2 million for unsecured notes payable and $0.5 million and $0.9 million for variable rate debt as of September 30, 2021 and December 31, 2020. (b) For further detail, refer to Note 5, ''Debt and Preferred Equity Investments." The Company used quoted market prices as of September 30, 2021 and December 31, 2020 to value the unsecured notes payable and, as such, categorized them as Level 2. The inputs utilized to determine the fair value of the Company’s variable rate debt are categorized as Level 3. The fair value of the variable rate debt was determined using a discounted cash flow model that considered borrowing rates available to the Company for loans with similar terms and characteristics. The inputs utilized to determine fair value of the Company's notes receivable are unobservable and, as such, were categorized as Level 3. Fair value was determined using a discounted cash flow model that considered the contractual interest and principal payments discounted at a blended interest rate of the notes receivable. For the Company’s level 3 financial instruments for which fair value is disclosed, an increase in the discount rate used to determine fair value would result in a decrease to the fair value. Conversely, a decrease in the discount rate would result in an increase to the fair value. Disclosure about the fair value of financial instruments is based upon pertinent information available to management as of September 30, 2021 and December 31, 2020. Although management is not aware of any factors that would significantly affect the fair value amounts, such amounts were not comprehensively revalued for purposes of these financial statements since September 30, 2021. Current estimates of fair value may differ from the amounts presented herein.

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	10. DERIVATIVE FINANCIAL INSTRUMENTS The following table summarizes the terms and fair values of the Company’s derivative financial instruments as of September 30, 2021 and December 31, 2020. The notional amounts provide an indication of the extent of the Company’s involvement in these instruments at that time, but do not represent exposure to credit, interest rate or market risks (amounts presented in thousands). Hedge Product Hedge Type Designation Notional Amount Strike Trade Date Maturity Date Fair value 9/30/2021 12/31/2020 9/30/2021 12/31/2020 Liabilities Swap Interest Rate Cash Flow (a) $ 250,000 $ 250,000 2.868 % October 8, 2015 October 8, 2022 $ (3,872) $ (6,627) Swap Interest Rate Cash Flow (b) — 25,774 3.300 % December 22, 2011 January 30, 2021 — (120) $ 250,000 $ 275,774 (a) Hedging unsecured variable rate debt. (b) On January 30, 2021, the interest rate hedge contract for this swap expired. The Company measures its derivative instruments at fair value and records them in “Other assets” and (“Other liabilities”) on the Company’s consolidated balance sheets. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. The Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation of its derivatives. As a result, the Company has determined that the inputs utilized to determine the fair value of derivative instruments are classified in Level 2 of the fair value hierarchy. Disclosure about the fair value of derivative instruments is based upon pertinent information available to management as of September 30, 2021 and December 31, 2020. Although management is not aware of any factors that would significantly affect the fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since September 30, 2021. Current estimates of fair value may differ from the amounts presented herein.

Limited Partners' Noncontrollin

Limited Partners' Noncontrolling Interests in the Parent Company	9 Months Ended
	Sep. 30, 2021
Noncontrolling Interest [Abstract]
LIMITED PARTNERS' NONCONTROLLING INTERESTS IN THE PARENT COMPANY	11. LIMITED PARTNERS' NONCONTROLLING INTERESTS IN THE PARENT COMPANY Noncontrolling interests in the Parent Company’s financial statements relate to redeemable common limited partnership interests in the Operating Partnership held by parties other than the Parent Company and properties which are consolidated but not wholly owned by the Operating Partnership. Operating Partnership The aggregate book value of the noncontrolling interests associated with the redeemable common limited partnership interests in the accompanying consolidated balance sheet of the Parent Company was $8.3 million and $10.5 million as of September 30, 2021 and December 31, 2020, respectively. Under the applicable accounting guidance, the redemption value of limited partnership units are carried at fair value. The Parent Company believes that the aggregate settlement value of these interests (based on the number of units outstanding and the average closing price of the common shares during the last five business days of the quarter) was approximately $11.2 million and $11.7 million as of September 30, 2021 and December 31, 2020, respectively.

Beneficiaries Equity of the Par

Beneficiaries Equity of the Parent Company	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
BENEFICIARIES' EQUITY OF THE PARENT COMPANY	12. BENEFICIARIES' EQUITY OF THE PARENT COMPANY Earnings per Share (EPS) The following table details the number of shares and net income used to calculate basic and diluted earnings per share (in thousands, except share and per share amounts; results may not add due to rounding): Three Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 974 $ 974 $ 276,133 $ 276,133 Net income attributable to noncontrolling interests (7) (7) (1,612) (1,612) Nonforfeitable dividends allocated to unvested restricted shareholders (91) (91) (93) (93) Net income attributable to common shareholders $ 876 $ 876 $ 274,428 $ 274,428 Denominator Weighted-average shares outstanding 170,907,018 170,907,018 170,573,028 170,573,028 Contingent securities/Share based compensation — 1,330,176 — 453,464 Weighted-average shares outstanding 170,907,018 172,237,194 170,573,028 171,026,492 Earnings per Common Share: Net income attributable to common shareholders $ 0.01 $ 0.01 $ 1.61 $ 1.60 Nine Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 7,763 $ 7,763 $ 288,240 $ 288,240 Net income attributable to noncontrolling interests (42) (42) (1,701) (1,701) Nonforfeitable dividends allocated to unvested restricted shareholders (331) (331) (317) (317) Net income attributable to common shareholders $ 7,390 $ 7,390 $ 286,222 $ 286,222 Denominator Weighted-average shares outstanding 170,794,585 170,794,585 172,380,410 172,380,410 Contingent securities/Share based compensation — 1,283,365 — 355,026 Weighted-average shares outstanding 170,794,585 172,077,950 172,380,410 172,735,436 Earnings per Common Share: Net income attributable to common shareholders $ 0.04 $ 0.04 $ 1.66 $ 1.66 Redeemable common limited partnership units totaling 823,983 at September 30, 2021 and 981,634 at September 30, 2020, were excluded from the diluted earnings per share computations because they are not dilutive. Unvested restricted shares are considered participating securities which require the use of the two-class method for the computation of basic and diluted earnings per share. For the three and nine months ended September 30, 2021 and 2020, earnings representing nonforfeitable dividends as noted in the table above were allocated to the unvested restricted shares issued to the Company’s executives and other employees under the Company's shareholder-approved long-term incentive plan. Common Shares On September 14, 2021, the Parent Company declared a distribution of $0.19 per common share, totaling $32.8 million, which was paid on October 20, 2021 to shareholders of record as of October 6, 2021. The Parent Company maintains a common share repurchase program under which the Board of Trustees has authorized the Parent Company to repurchase common shares. On January 3, 2019, the Board of Trustees authorized the repurchase of up to $150.0 million common shares from and after January 3, 2019. During the nine months ended September 30, 2021, the Company did not repurchase any common shares. During the nine months ended September 30, 2020, the Company repurchased and retired 6,248,483 common shares at an average price of $9.60 per share, totaling $60.0 million.

Partners' Equity Of The Parent

Partners' Equity Of The Parent Company	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
PARTNERS' EQUITY OF THE PARENT COMPANY	13. PARTNERS' EQUITY OF THE PARENT COMPANY Earnings per Common Partnership Unit The following table details the number of units and net income used to calculate basic and diluted earnings per common partnership unit (in thousands, except unit and per unit amounts; results may not add due to rounding): Three Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 974 $ 974 $ 276,133 $ 276,133 Net loss attributable to noncontrolling interests 2 2 2 2 Nonforfeitable dividends allocated to unvested restricted unitholders (91) (91) (93) (93) Net income attributable to common unitholders $ 885 $ 885 $ 276,042 $ 276,042 Denominator Weighted-average units outstanding 171,731,001 171,731,001 171,554,662 171,554,662 Contingent securities/Share based compensation — 1,330,176 — 453,464 Total weighted-average units outstanding 171,731,001 173,061,177 171,554,662 172,008,126 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.01 $ 0.01 $ 1.61 $ 1.60 Nine Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 7,763 $ 7,763 $ 288,240 $ 288,240 Net (income) loss attributable to noncontrolling interests 4 4 (20) (20) Nonforfeitable dividends allocated to unvested restricted unitholders (331) (331) (317) (317) Net income attributable to common unitholders $ 7,436 $ 7,436 $ 287,903 $ 287,903 Denominator Weighted-average units outstanding 171,710,387 171,710,387 173,362,044 173,362,044 Contingent securities/Share based compensation — 1,283,365 — 355,026 Total weighted-average units outstanding 171,710,387 172,993,752 173,362,044 173,717,070 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.04 $ 0.04 $ 1.66 $ 1.66 Unvested restricted units are considered participating securities which require the use of the two-class method for the computation of basic and diluted earnings per share. For the three and nine months ended September 30, 2021 and 2020, earnings representing nonforfeitable dividends were allocated to the unvested restricted units issued to the Parent Company's executives and other employees under the Parent Company's shareholder-approved long-term incentive plan. Common Partnership Units On September 14, 2021, the Operating Partnership declared a distribution of $0.19 per common partnership unit, totaling $32.8 million, which was paid on October 20, 2021 to unitholders of record as of October 6, 2021. In connection with the Parent Company’s common share repurchase program, one common unit of the Operating Partnership is retired for each common share repurchased. During the nine months ended September 30, 2021, the Company did not repurchase any units. During the nine months ended September 30, 2020, the Company retired 6,248,483 common partnership units at an average price of $9.60 per unit, totaling $60.0 million, in connection with an equal number of share repurchases.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
SEGMENT INFORMATION	14. SEGMENT INFORMATION As of September 30, 2021, the Company owns and manages properties within five segments: (1) Philadelphia Central Business District ("Philadelphia CBD"), (2) Pennsylvania Suburbs, (3) Austin, Texas (4) Metropolitan Washington, D.C. and (5) Other. The Philadelphia CBD segment includes properties located in the City of Philadelphia, Pennsylvania. The Pennsylvania Suburbs segment includes properties in Chester, Delaware, and Montgomery counties in the Philadelphia suburbs. The Austin, Texas segment includes properties in the City of Austin, Texas. The Metropolitan Washington, D.C. segment includes properties in the District of Columbia, Northern Virginia and Southern Maryland. The Other segment includes properties located in Camden County, New Jersey and New Castle County, Delaware. In addition to the five segments, the corporate group is responsible for cash and investment management, development of certain real estate properties during the construction period, and certain other general support functions. Land held for development and construction in progress is transferred to operating properties by region upon completion of the associated construction or project. The following tables provide selected asset information and results of operations of the Company's reportable segments (in thousands): Real estate investments, at cost: September 30, 2021 December 31, 2020 Philadelphia CBD $ 1,430,724 $ 1,433,927 Pennsylvania Suburbs 875,586 871,530 Austin, Texas 771,977 728,741 Metropolitan Washington, D.C. 271,929 352,794 Other 86,858 87,117 Operating Properties $ 3,437,074 $ 3,474,109 Corporate Right of use asset - operating leases, net $ 20,478 $ 20,977 Construction-in-progress $ 266,263 $ 210,311 Land held for development $ 118,684 $ 117,984 Prepaid leasehold interests in land held for development, net $ 27,762 $ 39,185 Net operating income: Three Months Ended September 30, 2021 2020 Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income (loss) Philadelphia CBD $ 51,587 $ (18,823) $ 32,764 $ 52,640 $ (18,522) $ 34,118 Pennsylvania Suburbs 31,327 (10,154) 21,173 34,649 (11,141) 23,508 Austin, Texas 24,813 (9,580) 15,233 25,328 (9,944) 15,384 Metropolitan Washington, D.C. 5,224 (3,806) 1,418 9,675 (5,236) 4,439 Other 3,638 (2,534) 1,104 3,188 (2,374) 814 Corporate 3,829 (2,155) 1,674 626 (1,782) (1,156) Operating properties $ 120,418 $ (47,052) $ 73,366 $ 126,106 $ (48,999) $ 77,107 Nine Months Ended September 30, 2021 2020 Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income (loss) Philadelphia CBD $ 154,259 $ (54,493) $ 99,766 $ 181,203 $ (65,615) 115,588 Pennsylvania Suburbs 93,361 (30,625) 62,736 106,569 (34,980) 71,589 Austin, Texas 76,501 (29,262) 47,239 76,921 (30,032) 46,889 Metropolitan Washington, D.C. 14,711 (11,907) 2,804 30,520 (15,678) 14,842 Other 10,513 (7,344) 3,169 10,221 (7,434) 2,787 Corporate 11,944 (7,522) 4,422 2,597 (4,652) (2,055) Operating properties $ 361,289 $ (141,153) $ 220,136 $ 408,031 $ (158,391) $ 249,640 Unconsolidated real estate ventures: Investment in real estate ventures Equity in income (loss) of real estate venture As of Three Months Ended September 30, Nine Months Ended September 30, September 30, 2021 December 31, 2020 2021 2020 2021 2020 Philadelphia CBD $ 319,645 $ 268,562 $ (3,602) $ (2,737) $ (12,542) $ (2,576) Metropolitan Washington, D.C. 97,972 99,769 (1,173) (1,367) (2,368) (2,463) Mid-Atlantic Office JV 32,041 32,996 310 — 634 — MAP Venture (22,247) (11,516) (2,169) (1,684) (6,522) (4,843) Total $ 427,411 $ 389,811 $ (6,634) $ (5,788) $ (20,798) $ (9,882) Net operating income (“NOI”) is a non-GAAP financial measure, which we define as total revenue less property operating expenses, real estate taxes and third party management expenses. Property operating expenses that are included in determining NOI consist of costs that are necessary and allocable to our operating properties such as utilities, property-level salaries, repairs and maintenance, property insurance and management fees. General and administrative expenses that are not reflected in NOI primarily consist of corporate-level salaries, amortization of share awards and professional fees that are incurred as part of corporate office management. NOI presented by the Company may not be comparable to NOI reported by other companies that define NOI differently. NOI is the primary measure that is used by the Company’s management to evaluate the operating performance of the Company’s real estate assets by segment. The Company believes NOI provides useful information to investors regarding the financial condition and results of operations because it reflects only those income and expense items that are incurred at the property level. While NOI is a relevant and widely used measure of operating performance of real estate investment trusts, it does not represent cash flow from operations or net income as defined by GAAP and should not be considered as an alternative to those measures in evaluating our liquidity or operating performance. NOI does not reflect interest expenses, real estate impairment losses, depreciation and amortization costs, capital expenditures and leasing costs. The Company believes that net income (loss), as defined by GAAP, is the most appropriate earnings measure. The following is a reconciliation of consolidated net income, as defined by GAAP, to consolidated NOI, (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Net income $ 974 $ 276,133 $ 7,763 $ 288,240 Plus: Interest expense 15,190 16,310 46,973 56,510 Interest expense - amortization of deferred financing costs 709 715 2,127 2,195 Depreciation and amortization 48,175 43,533 131,303 145,314 General and administrative expenses 7,076 7,069 22,016 23,973 Equity in loss of unconsolidated real estate ventures 6,634 5,788 20,798 9,882 Less: Interest and investment income 4,494 467 7,845 1,487 Income tax (provision) benefit (12) (2) (46) 224 Net gain on disposition of real estate — 271,901 142 274,487 Net gain on sale of undepreciated real estate 910 — 2,903 201 Net gain on real estate venture transactions — 75 — 75 Consolidated net operating income $ 73,366 $ 77,107 $ 220,136 $ 249,640

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	15. COMMITMENTS AND CONTINGENCIES Legal Proceedings The Company is involved from time to time in litigation on various matters, including disputes with tenants, vendors and disputes arising out of agreements to purchase or sell properties. Given the nature of the Company’s business activities, these lawsuits are considered routine to the conduct of its business. The result of any particular lawsuit cannot be predicted, because of the very nature of litigation, the litigation process and its adversarial nature, and the jury system. The Company will establish reserves for specific legal proceedings when it determines that the likelihood of an unfavorable outcome is probable and when the amount of loss is reasonably estimable. The Company does not expect that the liabilities, if any, that may ultimately result from such legal actions will have a material adverse effect on the consolidated financial position, results of operations or cash flows of the Company. Environmental As an owner of real estate, the Company is subject to various environmental laws of federal, state, and local governments. The Company’s compliance with existing laws has not had a material adverse effect on its financial condition and results of operations, and the Company does not believe it will have a material adverse effect in the future. However, the Company cannot predict the impact of unforeseen environmental contingencies or new or changed laws or regulations on its current Properties or on properties that the Company may acquire. Debt Guarantees As of September 30, 2021, the Company’s unconsolidated real estate ventures had aggregate indebtedness of $958.8 million. These loans are generally mortgage or construction loans, most of which are nonrecourse to the Company, except for customary recourse carve-outs. As of September 30, 2021, the $150.0 million construction loan obtained by 4040 Wilson, located in Arlington, Virginia, for which the Company has a payment guarantee up to $41.3 million, is recourse to the Company. In addition, during construction undertaken by the unconsolidated real estate ventures, including 4040 Wilson and 3025 JFK, the Company has provided, and expects to continue to provide, cost overrun and completion guarantees, as well as customary environmental indemnities and guarantees of customary exceptions to nonrecourse provisions in loan agreements. In the agreement with its partner in the 3025 JFK Venture, the Company agreed to provide cost overrun and completion guaranties for the project under development. With respect to the construction loan obtained by 3025 JFK Venture on July 23, 2021, the Company has also provided a carry guarantee and limited payment guarantee up to 25% of the principal balance. Impact of Natural Disasters and Casualty The Company carries liability insurance to mitigate its exposure to certain losses, including those relating to property damage. The Company records the estimated amount of expected insurance proceeds for property damage and other losses incurred as an asset (typically a receivable from the insurer) and income up to the amount of the losses incurred when receipt of insurance proceeds is deemed probable. Any amount of insurance recovery in excess of the amount of the losses is considered a gain contingency and is not recorded until the proceeds are received. In February 2021, one of the Company's properties in Austin, Texas sustained damage from the winter storms and resulting power grid failures. As a result of the damage, during the nine months ended September 30, 2021, the Company recorded a fixed asset write-off totaling $1.2 million. During the nine months ended September 30, 2021, the Company has recorded an estimated $7.2 million of restoration costs, of which $2.0 million is included in Accounts payable and accrued expenses on the consolidated balance sheets as of September 30, 2021. The Company has also sustained business interruption loss of $3.9 million related to unpaid rent, which is also fully covered under the insurance policy. During the nine months ended September 30, 2021, the Company has received $13.0 million of insurance proceeds, resulting in full recovery of the costs incurred to date. The $0.7 million of insurance proceeds received in excess of the fixed asset write-off, total business interruption, and total estimated restoration cost during the nine months ended September 30, 2021 is included in Other income on the consolidated statement of operations. Other Commitments or Contingencies In connection with the Schuylkill Yards Project, the Company entered into a neighborhood engagement program and, as of September 30, 2021, had $7.6 million of future fixed contractual obligations. The Company also committed to fund additional contributions under the program. As of September 30, 2021, the Company estimates that these additional contributions, which are not fixed under the terms of agreement, will be $2.4 million. In connection with the formation of the Commerce Square Venture, the Company has committed to investing an additional $20.0 million of preferred equity in the properties on a pari passu basis with its joint venture partner of which $2.1 million has been contributed by the Company as of September 30, 2021. The Company invests in its properties and regularly incurs capital expenditures in the ordinary course of business to maintain the properties. The Company believes that such expenditures enhance its competitiveness. The Company also enters into construction, utility and service contracts in the ordinary course of business which may extend beyond one year. These contracts typically provide for cancellation with insignificant or no cancellation penalties.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, all adjustments consist solely of normal recurring matters, and result in a fair statement of the financial position of the Company as of September 30, 2021, the results of its operations for the three and nine months ended September 30, 2021 and 2020 and its cash flows for the nine months ended September 30, 2021 and 2020. The results of operations for such interim periods are not necessarily indicative of the results for a full year. These consolidated financial statements should be read in conjunction with the Parent Company’s and the Operating Partnership’s consolidated financial statements and footnotes included in their combined Annual Report on Form 10-K for the year ended December 31, 2020 filed with the SEC on February 24, 2021. The consolidated balance sheet at December 31, 2020 has been derived from the audited financial statements as of that date but does not include all the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements. The Company's Annual Report on Form 10-K for the year ended December 31, 2020 contains a discussion of its significant accounting policies under Note 2, "Summary of Significant Accounting Policies" . There have been no significant changes in the Company's significant accounting policies since December 31, 2020.
Change in Depreciable Lives of Real Estate Investments	Change in Depreciable Lives of Real Estate Investments In accordance with its policy, the Company reviews the estimated useful lives of its real estate investments on an ongoing basis. Pu rsuant to our Broadmoor master development plans, the estimated useful lives of seven properties in Austin, Texas were modified to reflect the estimated periods during which these assets will remain in service. The estimated useful lives of the properties that were approximately 35 years were decreased to approximately 12 years. The effect of this change in estimate was a $3.3 million and $6.5 million increase in depreciation expense during the three and nine months ended September 30, 2021, respectively.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04 Reference Rate Reform (Topic 848) Facilitation of the Effects of Reference Rate Reform on Financial Reporting. The amendments provide practical expedients for reference rate reform related activities that impact debt, leases, derivatives and other contracts. The guidance is optional and is effective between March 12, 2020 and December 31, 2022. The guidance may be elected over time as reference rate reform activities occur. The Company continues to evaluate the impact of the guidance and may apply elections as applicable as additional changes in the market occur.

Organization of the Parent Co_2

Organization of the Parent Company and The Operating Partnership (Tables)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Core Portfolio of Operating Properties and Excludes Development, Redevelopment and Held for Sale	The Company’s core portfolio of operating properties (the “Core Properties”) excludes development properties, redevelopment properties, and properties held for sale. The Properties were comprised of the following as of September 30, 2021: Number of Properties Rentable Square Feet Office properties 71 12,006,744 Mixed-use properties 5 942,334 Core Properties 76 12,949,078 Development property 1 205,803 Redevelopment properties 4 496,769 The Properties 81 13,651,650

Real Estate Investments (Tables

Real Estate Investments (Tables)	9 Months Ended
	Sep. 30, 2021
Real Estate [Abstract]
Gross Carrying Value of Operating Properties	As of September 30, 2021 and December 31, 2020, the gross carrying value of the operating properties was as follows (in thousands): September 30, 2021 December 31, 2020 Land $ 391,261 $ 407,514 Building and improvements 2,640,229 2,665,232 Tenant improvements 405,584 401,363 Total $ 3,437,074 $ 3,474,109
Summary of Properties Sold	The following table summarizes the property dispositions during the nine months ended September 30, 2021 (dollars in thousands): Property/Portfolio Name Disposition Date Location Property Type Rentable Square Feet/Acres Sales Price Gain/(Loss) on Sale (a) 2100-2200 Lenox Drive July 6, 2021 Lawrenceville, NJ Land 35.2 acres $ 8,900 $ 842 1100 Lenox Drive September 8, 2021 Lawrenceville, NJ Land 5.0 acres $ 2,575 $ 68 (a) Gain/(Loss) on Sale is net of closing and other transaction related costs.

Investment in Unconsolidated _2

Investment in Unconsolidated Real Estate Ventures (Tables)	9 Months Ended
	Sep. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Summary of Financial Position of Real Estate Ventures	The following is a summary of the financial position of the unconsolidated real estate ventures in which the Company held interests as of September 30, 2021 and December 31, 2020 (in thousands): September 30, 2021 December 31, 2020 Net property $ 1,573,569 $ 1,520,804 Other assets 443,610 488,805 Other liabilities 328,446 333,049 Debt, net 954,213 956,688 Equity (a) 734,520 719,872 (a) This amount does not include the effect of the basis difference between the Company's historical cost basis and the basis recorded at the real estate venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from the impairment of investments, purchases of third party interests in existing real estate ventures and upon the transfer of assets that were previously owned by the Company into a real estate venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the real estate venture level.
Investment in Real Estate Ventures and Share of Real Estate Ventures' Income (Loss)	The following is a summary of results of operations of the unconsolidated real estate ventures in which the Company held interests during the three and nine month periods ended September 30, 2021 and 2020 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Revenue $ 53,991 $ 43,109 $ 160,576 $ 105,554 Operating expenses (29,650) (23,870) (87,266) (59,838) Interest expense, net (8,024) (6,175) (23,414) (16,320) Depreciation and amortization (23,038) (22,345) (73,431) (47,493) Provision for impairment (1,125) — (1,125) — Net loss $ (7,846) $ (9,281) $ (24,660) $ (18,097) Ownership interest % Various Various Various Various Company's share of net loss $ (6,572) $ (5,812) $ (20,394) $ (9,892) Basis adjustments and other (62) 24 (404) 10 Equity in loss of unconsolidated real estate ventures $ (6,634) $ (5,788) $ (20,798) $ (9,882)

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Schedule of Lease Income	The table below sets forth the allocation of lease revenue between fixed contractual payments and variable lease payments for the three and nine months ended September 30, 2021 and 2020 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Lease Revenue 2021 2020 2021 2020 Fixed contractual payments $ 87,498 $ 95,751 $ 259,995 $ 302,146 Variable lease payments 21,265 22,716 67,473 80,824 Total $ 108,763 $ 118,467 $ 327,468 $ 382,970

Intangible Assets and Liabili_2

Intangible Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets and Liabilities	As of September 30, 2021 and December 31, 2020, the Company’s intangible assets/liabilities were comprised of the following (in thousands): September 30, 2021 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 80,630 $ (46,386) $ 34,244 Tenant relationship value 167 (95) 72 Above market leases acquired 486 (288) 198 Total intangible assets, net $ 81,283 $ (46,769) $ 34,514 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 28,881 $ (14,430) $ 14,451 December 31, 2020 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 91,552 $ (43,400) $ 48,152 Tenant relationship value 2,091 (1,938) 153 Above market leases acquired 530 (265) 265 Total intangible assets, net $ 94,173 $ (45,603) $ 48,570 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 31,263 $ (12,815) $ 18,448
Summary of Amortization for Intangible Assets and Liabilities	As of September 30, 2021, the Company’s annual amortization for its intangible assets/liabilities, assuming no prospective early lease terminations, was as follows (dollars in thousands): Assets Liabilities 2021 (three months remaining) $ 3,711 $ 1,129 2022 9,807 2,645 2023 7,218 1,609 2024 4,993 1,392 2025 3,805 1,115 Thereafter 4,980 6,561 Total $ 34,514 $ 14,451

Debt Obligations (Tables)

Debt Obligations (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Consolidated Debt Obligations	The following table sets forth information regarding the Company’s consolidated debt obligations outstanding as of September 30, 2021 and December 31, 2020 (in thousands): September 30, 2021 December 31, 2020 Effective Maturity UNSECURED DEBT $600 million Unsecured Credit Facility $ — $ — LIBOR + 1.10% July 2022 (a) Seven 250,000 250,000 2.87% October 2022 $350.0M 3.95% Guaranteed Notes due 2023 350,000 350,000 3.87% February 2023 $350.0M 4.10% Guaranteed Notes due 2024 350,000 350,000 3.78% October 2024 $450.0M 3.95% Guaranteed Notes due 2027 450,000 450,000 4.03% November 2027 $350.0M 4.55% Guaranteed Notes due 2029 350,000 350,000 4.30% October 2029 Indenture IA (Preferred Trust I) 27,062 27,062 LIBOR + 1.25% March 2035 Indenture IB (Preferred Trust I) 25,774 25,774 LIBOR + 1.25% April 2035 Indenture II (Preferred Trust II) 25,774 25,774 LIBOR + 1.25% July 2035 Principal balance outstanding 1,828,610 1,828,610 Plus: original issue premium (discount), net 8,675 10,137 Less: deferred financing costs (6,696) (8,152) Total unsecured indebtedness $ 1,830,589 $ 1,830,595
Schedule of Maturities of Long-term Debt	As of September 30, 2021, the aggregate scheduled principal payments on the Company's debt obligations were as follows (in thousands): 2021 (three months remaining) $ — 2022 250,000 2023 350,000 2024 350,000 2025 — Thereafter 878,610 Total principal payments 1,828,610 Net unamortized premiums/(discounts) 8,675 Net deferred financing costs (6,696) Outstanding indebtedness $ 1,830,589

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Financial Instruments with Fair Values Different from their Carrying Amount	The following are financial instruments for which the Company’s estimates of fair value differ from the carrying amounts (in thousands): September 30, 2021 December 31, 2020 Carrying Amount (a) Fair Value Carrying Amount (a) Fair Value Unsecured notes payable $ 1,502,502 $ 1,623,840 $ 1,502,901 $ 1,607,310 Variable rate debt $ 328,087 $ 309,523 $ 327,694 $ 308,838 Notes receivable (b) $ 44,430 $ 46,266 $ 94,430 $ 97,372 (a) Net of deferred financing costs of $6.2 million and $7.2 million for unsecured notes payable and $0.5 million and $0.9 million for variable rate debt as of September 30, 2021 and December 31, 2020.

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following table summarizes the terms and fair values of the Company’s derivative financial instruments as of September 30, 2021 and December 31, 2020. The notional amounts provide an indication of the extent of the Company’s involvement in these instruments at that time, but do not represent exposure to credit, interest rate or market risks (amounts presented in thousands). Hedge Product Hedge Type Designation Notional Amount Strike Trade Date Maturity Date Fair value 9/30/2021 12/31/2020 9/30/2021 12/31/2020 Liabilities Swap Interest Rate Cash Flow (a) $ 250,000 $ 250,000 2.868 % October 8, 2015 October 8, 2022 $ (3,872) $ (6,627) Swap Interest Rate Cash Flow (b) — 25,774 3.300 % December 22, 2011 January 30, 2021 — (120) $ 250,000 $ 275,774 (a) Hedging unsecured variable rate debt. (b) On January 30, 2021, the interest rate hedge contract for this swap expired.

Beneficiaries Equity of the P_2

Beneficiaries Equity of the Parent Company (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Earnings Per Share (EPS), Basic and Diluted	The following table details the number of shares and net income used to calculate basic and diluted earnings per share (in thousands, except share and per share amounts; results may not add due to rounding): Three Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 974 $ 974 $ 276,133 $ 276,133 Net income attributable to noncontrolling interests (7) (7) (1,612) (1,612) Nonforfeitable dividends allocated to unvested restricted shareholders (91) (91) (93) (93) Net income attributable to common shareholders $ 876 $ 876 $ 274,428 $ 274,428 Denominator Weighted-average shares outstanding 170,907,018 170,907,018 170,573,028 170,573,028 Contingent securities/Share based compensation — 1,330,176 — 453,464 Weighted-average shares outstanding 170,907,018 172,237,194 170,573,028 171,026,492 Earnings per Common Share: Net income attributable to common shareholders $ 0.01 $ 0.01 $ 1.61 $ 1.60 Nine Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 7,763 $ 7,763 $ 288,240 $ 288,240 Net income attributable to noncontrolling interests (42) (42) (1,701) (1,701) Nonforfeitable dividends allocated to unvested restricted shareholders (331) (331) (317) (317) Net income attributable to common shareholders $ 7,390 $ 7,390 $ 286,222 $ 286,222 Denominator Weighted-average shares outstanding 170,794,585 170,794,585 172,380,410 172,380,410 Contingent securities/Share based compensation — 1,283,365 — 355,026 Weighted-average shares outstanding 170,794,585 172,077,950 172,380,410 172,735,436 Earnings per Common Share: Net income attributable to common shareholders $ 0.04 $ 0.04 $ 1.66 $ 1.66 The following table details the number of units and net income used to calculate basic and diluted earnings per common partnership unit (in thousands, except unit and per unit amounts; results may not add due to rounding): Three Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 974 $ 974 $ 276,133 $ 276,133 Net loss attributable to noncontrolling interests 2 2 2 2 Nonforfeitable dividends allocated to unvested restricted unitholders (91) (91) (93) (93) Net income attributable to common unitholders $ 885 $ 885 $ 276,042 $ 276,042 Denominator Weighted-average units outstanding 171,731,001 171,731,001 171,554,662 171,554,662 Contingent securities/Share based compensation — 1,330,176 — 453,464 Total weighted-average units outstanding 171,731,001 173,061,177 171,554,662 172,008,126 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.01 $ 0.01 $ 1.61 $ 1.60 Nine Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 7,763 $ 7,763 $ 288,240 $ 288,240 Net (income) loss attributable to noncontrolling interests 4 4 (20) (20) Nonforfeitable dividends allocated to unvested restricted unitholders (331) (331) (317) (317) Net income attributable to common unitholders $ 7,436 $ 7,436 $ 287,903 $ 287,903 Denominator Weighted-average units outstanding 171,710,387 171,710,387 173,362,044 173,362,044 Contingent securities/Share based compensation — 1,283,365 — 355,026 Total weighted-average units outstanding 171,710,387 172,993,752 173,362,044 173,717,070 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.04 $ 0.04 $ 1.66 $ 1.66

Partners' Equity Of The Paren_2

Partners' Equity Of The Parent Company (Tables)	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Earnings Per Share (EPS), Basic and Diluted	The following table details the number of shares and net income used to calculate basic and diluted earnings per share (in thousands, except share and per share amounts; results may not add due to rounding): Three Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 974 $ 974 $ 276,133 $ 276,133 Net income attributable to noncontrolling interests (7) (7) (1,612) (1,612) Nonforfeitable dividends allocated to unvested restricted shareholders (91) (91) (93) (93) Net income attributable to common shareholders $ 876 $ 876 $ 274,428 $ 274,428 Denominator Weighted-average shares outstanding 170,907,018 170,907,018 170,573,028 170,573,028 Contingent securities/Share based compensation — 1,330,176 — 453,464 Weighted-average shares outstanding 170,907,018 172,237,194 170,573,028 171,026,492 Earnings per Common Share: Net income attributable to common shareholders $ 0.01 $ 0.01 $ 1.61 $ 1.60 Nine Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 7,763 $ 7,763 $ 288,240 $ 288,240 Net income attributable to noncontrolling interests (42) (42) (1,701) (1,701) Nonforfeitable dividends allocated to unvested restricted shareholders (331) (331) (317) (317) Net income attributable to common shareholders $ 7,390 $ 7,390 $ 286,222 $ 286,222 Denominator Weighted-average shares outstanding 170,794,585 170,794,585 172,380,410 172,380,410 Contingent securities/Share based compensation — 1,283,365 — 355,026 Weighted-average shares outstanding 170,794,585 172,077,950 172,380,410 172,735,436 Earnings per Common Share: Net income attributable to common shareholders $ 0.04 $ 0.04 $ 1.66 $ 1.66 The following table details the number of units and net income used to calculate basic and diluted earnings per common partnership unit (in thousands, except unit and per unit amounts; results may not add due to rounding): Three Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 974 $ 974 $ 276,133 $ 276,133 Net loss attributable to noncontrolling interests 2 2 2 2 Nonforfeitable dividends allocated to unvested restricted unitholders (91) (91) (93) (93) Net income attributable to common unitholders $ 885 $ 885 $ 276,042 $ 276,042 Denominator Weighted-average units outstanding 171,731,001 171,731,001 171,554,662 171,554,662 Contingent securities/Share based compensation — 1,330,176 — 453,464 Total weighted-average units outstanding 171,731,001 173,061,177 171,554,662 172,008,126 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.01 $ 0.01 $ 1.61 $ 1.60 Nine Months Ended September 30, 2021 2020 Basic Diluted Basic Diluted Numerator Net income $ 7,763 $ 7,763 $ 288,240 $ 288,240 Net (income) loss attributable to noncontrolling interests 4 4 (20) (20) Nonforfeitable dividends allocated to unvested restricted unitholders (331) (331) (317) (317) Net income attributable to common unitholders $ 7,436 $ 7,436 $ 287,903 $ 287,903 Denominator Weighted-average units outstanding 171,710,387 171,710,387 173,362,044 173,362,044 Contingent securities/Share based compensation — 1,283,365 — 355,026 Total weighted-average units outstanding 171,710,387 172,993,752 173,362,044 173,717,070 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.04 $ 0.04 $ 1.66 $ 1.66

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Real Estate Investments, Net Operating Income and Unconsolidated Real Estate Ventures of Reportable Segments	The following tables provide selected asset information and results of operations of the Company's reportable segments (in thousands): Real estate investments, at cost: September 30, 2021 December 31, 2020 Philadelphia CBD $ 1,430,724 $ 1,433,927 Pennsylvania Suburbs 875,586 871,530 Austin, Texas 771,977 728,741 Metropolitan Washington, D.C. 271,929 352,794 Other 86,858 87,117 Operating Properties $ 3,437,074 $ 3,474,109 Corporate Right of use asset - operating leases, net $ 20,478 $ 20,977 Construction-in-progress $ 266,263 $ 210,311 Land held for development $ 118,684 $ 117,984 Prepaid leasehold interests in land held for development, net $ 27,762 $ 39,185 Net operating income: Three Months Ended September 30, 2021 2020 Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income (loss) Philadelphia CBD $ 51,587 $ (18,823) $ 32,764 $ 52,640 $ (18,522) $ 34,118 Pennsylvania Suburbs 31,327 (10,154) 21,173 34,649 (11,141) 23,508 Austin, Texas 24,813 (9,580) 15,233 25,328 (9,944) 15,384 Metropolitan Washington, D.C. 5,224 (3,806) 1,418 9,675 (5,236) 4,439 Other 3,638 (2,534) 1,104 3,188 (2,374) 814 Corporate 3,829 (2,155) 1,674 626 (1,782) (1,156) Operating properties $ 120,418 $ (47,052) $ 73,366 $ 126,106 $ (48,999) $ 77,107 Nine Months Ended September 30, 2021 2020 Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income (loss) Philadelphia CBD $ 154,259 $ (54,493) $ 99,766 $ 181,203 $ (65,615) 115,588 Pennsylvania Suburbs 93,361 (30,625) 62,736 106,569 (34,980) 71,589 Austin, Texas 76,501 (29,262) 47,239 76,921 (30,032) 46,889 Metropolitan Washington, D.C. 14,711 (11,907) 2,804 30,520 (15,678) 14,842 Other 10,513 (7,344) 3,169 10,221 (7,434) 2,787 Corporate 11,944 (7,522) 4,422 2,597 (4,652) (2,055) Operating properties $ 361,289 $ (141,153) $ 220,136 $ 408,031 $ (158,391) $ 249,640 Unconsolidated real estate ventures: Investment in real estate ventures Equity in income (loss) of real estate venture As of Three Months Ended September 30, Nine Months Ended September 30, September 30, 2021 December 31, 2020 2021 2020 2021 2020 Philadelphia CBD $ 319,645 $ 268,562 $ (3,602) $ (2,737) $ (12,542) $ (2,576) Metropolitan Washington, D.C. 97,972 99,769 (1,173) (1,367) (2,368) (2,463) Mid-Atlantic Office JV 32,041 32,996 310 — 634 — MAP Venture (22,247) (11,516) (2,169) (1,684) (6,522) (4,843) Total $ 427,411 $ 389,811 $ (6,634) $ (5,788) $ (20,798) $ (9,882)
Reconciliation of Consolidated Net Income to Consolidated NOI	The following is a reconciliation of consolidated net income, as defined by GAAP, to consolidated NOI, (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Net income $ 974 $ 276,133 $ 7,763 $ 288,240 Plus: Interest expense 15,190 16,310 46,973 56,510 Interest expense - amortization of deferred financing costs 709 715 2,127 2,195 Depreciation and amortization 48,175 43,533 131,303 145,314 General and administrative expenses 7,076 7,069 22,016 23,973 Equity in loss of unconsolidated real estate ventures 6,634 5,788 20,798 9,882 Less: Interest and investment income 4,494 467 7,845 1,487 Income tax (provision) benefit (12) (2) (46) 224 Net gain on disposition of real estate — 271,901 142 274,487 Net gain on sale of undepreciated real estate 910 — 2,903 201 Net gain on real estate venture transactions — 75 — 75 Consolidated net operating income $ 73,366 $ 77,107 $ 220,136 $ 249,640

Organization of The Parent Co_3

Organization of The Parent Company and The Operating Partnership - Narrative (Details)	9 Months Ended
	Sep. 30, 2021ft²apropertyparcel
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of real estate properties | property	81
Rentable Square Feet	13,651,650
Unconsolidated Properties | Unconsolidated Real Estate Ventures
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of real estate properties | property	10
Parent Company
Organization of The Parent Company and The Operating Partnership [Line Items]
Areas of land held for development (in acres) | a	176.1
Area of land held for sale | a	10
Lease agreement term	99 years
Area of additional undeveloped parcels of land with option to purchase (in acres) | a	55.5
Total potential development capacity (in square feet)	13,400,000
Parent Company | Land Parcel One
Organization of The Parent Company and The Operating Partnership [Line Items]
Lease agreement term	99 years
Parent Company | Held-for-sale
Organization of The Parent Company and The Operating Partnership [Line Items]
Total potential development capacity (in square feet)	100,000
Parent Company | Leashold Interest Land
Organization of The Parent Company and The Operating Partnership [Line Items]
Areas of land held for development (in acres) | a	0.8
Number of parcels of land | parcel	1
Wholly-owned Management Company Subsidiaries
Organization of The Parent Company and The Operating Partnership [Line Items]
Rentable Square Feet	24,400,000
Wholly-owned Management Company Subsidiaries | Wholly Owned Properties
Organization of The Parent Company and The Operating Partnership [Line Items]
Rentable Square Feet	13,700,000
Wholly-owned Management Company Subsidiaries | Partially Owned Properties
Organization of The Parent Company and The Operating Partnership [Line Items]
Rentable Square Feet	10,700,000
Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	99.50%

Organization of The Parent Co_4

Organization of The Parent Company and The Operating Partnership - Summary of Core Portfolio of Operating Properties and Excludes Development, Redevelopment and Held for Sale (Details)	Sep. 30, 2021ft²property
Real Estate Properties [Line Items]
Number of Properties | property	81
Rentable area | ft²	13,651,650
Office properties
Real Estate Properties [Line Items]
Number of Properties | property	71
Rentable area | ft²	12,006,744
Mixed-use properties
Real Estate Properties [Line Items]
Number of Properties | property	5
Rentable area | ft²	942,334
Core Properties
Real Estate Properties [Line Items]
Number of Properties | property	76
Rentable area | ft²	12,949,078
Development property
Real Estate Properties [Line Items]
Number of Properties | property	1
Rentable area | ft²	205,803
Redevelopment properties
Real Estate Properties [Line Items]
Number of Properties | property	4
Rentable area | ft²	496,769

Basis of Presentation - Narrati

Basis of Presentation - Narrative (Details) - Service Life $ in Millions	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)property	Sep. 30, 2021property	Sep. 30, 2021USD ($)property	Dec. 31, 2020
Schedule Of Basis Of Presentation [Line Items]
Number of properties that changed estimated useful lives | property	7	7	7
Property, plant, and equipment, estimated useful life		12 years		35 years
Depreciation | $	$ 3.3		$ 6.5

Real Estate Investments - Gross

Real Estate Investments - Gross Carrying Value of Operating Properties (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Real Estate [Abstract]
Land	$ 391,261	$ 407,514
Building and improvements	2,640,229	2,665,232
Tenant improvements	405,584	401,363
Total	$ 3,437,074	$ 3,474,109

Real Estate Investments - Summa

Real Estate Investments - Summary of Property Dispositions (Details) $ in Thousands	Sep. 08, 2021USD ($)ft²	Jul. 06, 2021USD ($)ft²	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Sale			$ 0	$ 271,901	$ 142	$ 274,487
Land | 2100-2200 Lenox Drive
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable Square Feet/Acres | ft²		35.2
Sales Price		$ 8,900
Gain (Loss) on Sale		$ 842
Land | 1100 Lenox Drive
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable Square Feet/Acres | ft²	5
Sales Price	$ 2,575
Gain (Loss) on Sale	$ 68

Real Estate Investments - Textu

Real Estate Investments - Textual (Details) $ in Thousands	Feb. 02, 2021USD ($)	Sep. 30, 2021USD ($)aparcel	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)aparcel	Sep. 30, 2020USD ($)	Feb. 02, 2021ft²	Feb. 02, 2021a	Dec. 31, 2020USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Investment in real estate ventures		$ 427,411		$ 427,411				$ 389,811
Net gain on sale of undepreciated real estate		910	$ 0	2,903	$ 201
Assets held for sale, net		562		562				$ 7,349
Held-for-sale | Other - Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, net		$ 600		$ 600
Held-for-sale | Other - Land | Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of land (in acres) | a		10		10
Number of parcels of land | parcel		2		2
3025 JFK Venture
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Lease agreement term	99 years
Area of land (in acres)						1	1
Investment in real estate ventures	$ 34,800
Net gain on sale of undepreciated real estate	$ 2,000

Investment in Unconsolidated _3

Investment in Unconsolidated Real Estate Ventures - Textual (Details) $ in Thousands	Feb. 02, 2021USD ($)	Sep. 30, 2021USD ($)aft²propertyapartment	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)aft²propertyapartment	Sep. 30, 2020USD ($)	Jul. 23, 2021USD ($)	Feb. 02, 2021ft²	Feb. 02, 2021a	Feb. 02, 2021	Dec. 31, 2020USD ($)
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property		81		81
Investment in unconsolidated real estate ventures		$ 449,658		$ 449,658						$ 401,327
Accounts receivable		11,645		11,645						13,536
Investment in real estate ventures		$ 427,411		$ 427,411						389,811
Brandywine Al Venture L L C | Fairview Properties
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%		50.00%
Impairment charge		$ 1,100
Brandywine Al Venture L L C | Fairview Properties | Brandywine Realty Trust
Schedule of Equity Method Investments [Line Items]
Impairment charge		600
3025 JFK Venture
Schedule of Equity Method Investments [Line Items]
Area of land (in acres)							1	1
Equity method investment, ownership percentage									55.00%
Lease agreement term	99 years
Investment in real estate ventures	$ 34,800
Area of building to be constructed | ft²							570,000
Estimated project cost	287,300
Joint venture, funding committed by other party	$ 45,200
Ownership interest held by partner									45.00%
Joint venture, funding committed		20,500		$ 20,500
Construction loan amount						$ 186,700
3025 JFK Venture | LIBOR
Schedule of Equity Method Investments [Line Items]
Construction loan, interest rate						3.50%
Interest rate, floor						0.25%
Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Accounts receivable		2,000		2,000						$ 1,200
Management Fees | Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Service and other revenue		2,100	$ 1,300	6,200	$ 3,200
Leasing Commission Income | Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Service and other revenue		$ 700	$ 200	$ 2,600	$ 900
Minimum
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		15.00%		15.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		70.00%		70.00%
Unconsolidated Real Estate Ventures
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated real estate ventures		$ 427,400		$ 427,400
Unconsolidated Real Estate Ventures | Office properties
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		5		5
Rentable area (in square feet) | ft²		8,400,000		8,400,000
Unconsolidated Real Estate Ventures | Other Liabilities
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated real estate ventures		$ 22,200		$ 22,200
Unconsolidated Real Estate Ventures | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property		10		10
Number of properties with negative investment balances | property		1		1
Unconsolidated Real Estate Ventures | Land Held For Development
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		2		2
Area of land (in acres) | a		1.4		1.4
Unconsolidated Real Estate Ventures | Land Under Active Development
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		1		1
Area of land (in acres) | a		1		1
Unconsolidated Real Estate Ventures | Mixed Use Tower
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		1		1
Rentable area (in square feet) | ft²		200,000		200,000
Number of apartment units (in units) | apartment		250		250
Unconsolidated Real Estate Ventures | Residential Tower
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | property		1		1
Number of apartment units (in units) | apartment		321		321

Investment in Unconsolidated _4

Investment in Unconsolidated Real Estate Ventures - Summary of Financial Position of Real Estate Ventures (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Net property	$ 2,912,468			$ 2,966,005
Other assets	131,230			176,747
Other liabilities	48,090			47,573
Debt, net	1,830,589
Equity	1,725,477	$ 1,751,053	$ 1,782,254	1,804,648	$ 1,815,782	$ 1,570,849	$ 1,603,814	$ 1,688,303
Investment In Nonconsolidated Real Estate
Schedule of Equity Method Investments [Line Items]
Net property	1,573,569			1,520,804
Other assets	443,610			488,805
Other liabilities	328,446			333,049
Debt, net	954,213			956,688
Equity	$ 734,520			$ 719,872

Investment in Unconsolidated _5

Investment in Unconsolidated Real Estate Ventures - Summary of Results of Operations of Real Estate Ventures with Interests (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule of Equity Method Investments [Line Items]
Revenue	$ 120,418			$ 126,106			$ 361,289	$ 408,031
Operating expenses	(102,303)			(99,601)			(294,472)	(327,678)
Interest expense	(15,190)			(16,310)			(46,973)	(56,510)
Depreciation and amortization	(48,175)			(43,533)			(131,303)	(145,314)
Net income	974	$ (175)	$ 6,964	276,133	$ 4,020	$ 8,087	7,763	288,240
Equity in loss of unconsolidated real estate ventures	(6,634)			(5,788)			(20,798)	(9,882)
Investment In Nonconsolidated Real Estate
Schedule of Equity Method Investments [Line Items]
Revenue	53,991			43,109			160,576	105,554
Operating expenses	(29,650)			(23,870)			(87,266)	(59,838)
Interest expense	(8,024)			(6,175)			(23,414)	(16,320)
Depreciation and amortization	(23,038)			(22,345)			(73,431)	(47,493)
Provision for impairment	(1,125)			0			(1,125)	0
Net income	(7,846)			(9,281)			(24,660)	(18,097)
Company's share of net loss	(6,572)			(5,812)			(20,394)	(9,892)
Basis adjustments and other	(62)			24			(404)	10
Equity in loss of unconsolidated real estate ventures	$ (6,634)			$ (5,788)			$ (20,798)	$ (9,882)

Debt and Preferred Equity Inv_2

Debt and Preferred Equity Investments (Details)	Dec. 31, 2020USD ($)property	Sep. 30, 2021USD ($)property	Dec. 31, 2018USD ($)	Sep. 03, 2021USD ($)
Summary of Investment Holdings [Line Items]
Number of real estate properties | property		81
Austin Preferred Equity Investment | Notes Receivable
Summary of Investment Holdings [Line Items]
Note receivable	$ 50,000,000
Number of real estate properties | property	2
Notes receivable, interest rate	9.00%
Extension option term	1 year
Note receivable repurchased amount				$ 50,000,000
Gain on financing receivable redemption		$ 2,800,000
Brandywine 1919 Ventures
Summary of Investment Holdings [Line Items]
Note receivable			$ 44,400,000
Notes receivable, interest rate			4.00%
Debt, net			$ 44,400,000
Repayment of construction loan			$ 88,800,000

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Fixed contractual payments	$ 87,498	$ 95,751	$ 259,995	$ 302,146
Variable lease payments	21,265	22,716	67,473	80,824
Total	$ 108,763	$ 118,467	$ 327,468	$ 382,970

Intangible Assets and Liabili_3

Intangible Assets and Liabilities - Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Intangible Assets [Line Items]
Intangible assets, total cost	$ 81,283	$ 94,173
Intangible assets, accumulated amortization	(46,769)	(45,603)
Intangible Assets, net	34,514	48,570
Intangible liabilities, total cost	28,881	31,263
Intangible liabilities, accumulated amortization	(14,430)	(12,815)
Intangible Liabilities, net	14,451	18,448
In-place lease value
Intangible Assets [Line Items]
Intangible assets, total cost	80,630	91,552
Intangible assets, accumulated amortization	(46,386)	(43,400)
Intangible Assets, net	34,244	48,152
Tenant relationship value
Intangible Assets [Line Items]
Intangible assets, total cost	167	2,091
Intangible assets, accumulated amortization	(95)	(1,938)
Intangible Assets, net	72	153
Above market leases acquired
Intangible Assets [Line Items]
Intangible assets, total cost	486	530
Intangible assets, accumulated amortization	(288)	(265)
Intangible Assets, net	$ 198	$ 265

Intangible Assets and Liabili_4

Intangible Assets and Liabilities - Annual Amortization of Intangible Assets, Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets
2021 (three months remaining)	$ 3,711
2022	9,807
2023	7,218
2024	4,993
2025	3,805
Thereafter	4,980
Intangible Assets, net	34,514	$ 48,570
Liabilities
2021 (three months remaining)	1,129
2022	2,645
2023	1,609
2024	1,392
2025	1,115
Thereafter	6,561
Intangible Liabilities, net	$ 14,451	$ 18,448

Debt Obligations - Consolidated

Debt Obligations - Consolidated Debt Obligations Outstanding (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Consolidated debt obligations
Principal balance outstanding	$ 1,828,610,000
Plus: original issue premium (discount), net	(8,675,000)
Less: deferred financing costs	(6,696,000)
Debt, net	1,830,589,000
Unsecured Debt
Consolidated debt obligations
Principal balance outstanding	1,828,610,000	$ 1,828,610,000
Plus: original issue premium (discount), net	8,675,000	10,137,000
Less: deferred financing costs	(6,696,000)	(8,152,000)
Debt, net	1,830,589,000	1,830,595,000
Unsecured Debt | $600 million Unsecured Credit Facility
Consolidated debt obligations
Debt instrument, face amount	600,000,000
Principal balance outstanding	$ 0	0
Unsecured Debt | $600 million Unsecured Credit Facility | LIBOR
Consolidated debt obligations
Spread on variable rate	1.10%
Unsecured Debt | Seven-Year Term Loan - Swapped to fixed
Consolidated debt obligations
Debt instrument, term	7 years
Principal balance outstanding	$ 250,000,000	250,000,000
Effective interest rate	2.87%
Unsecured Debt | $350.0M 3.95% Guaranteed Notes due 2023
Consolidated debt obligations
Debt instrument, face amount	$ 350,000,000
Debt instrument, interest rate, stated percentage	3.95%
Principal balance outstanding	$ 350,000,000	350,000,000
Effective interest rate	3.87%
Unsecured Debt | $350.0M 4.10% Guaranteed Notes due 2024
Consolidated debt obligations
Debt instrument, face amount	$ 350,000,000
Debt instrument, interest rate, stated percentage	4.10%
Principal balance outstanding	$ 350,000,000	350,000,000
Effective interest rate	3.78%
Unsecured Debt | $450.0M 3.95% Guaranteed Notes due 2027
Consolidated debt obligations
Debt instrument, face amount	$ 450,000,000
Debt instrument, interest rate, stated percentage	3.95%
Principal balance outstanding	$ 450,000,000	450,000,000
Effective interest rate	4.03%
Unsecured Debt | $350.0M 4.55% Guaranteed Notes due 2029
Consolidated debt obligations
Debt instrument, face amount	$ 350,000,000
Debt instrument, interest rate, stated percentage	4.55%
Principal balance outstanding	$ 350,000,000	350,000,000
Effective interest rate	4.30%
Unsecured Debt | Indenture IA (Preferred Trust I)
Consolidated debt obligations
Principal balance outstanding	$ 27,062,000	27,062,000
Unsecured Debt | Indenture IA (Preferred Trust I) | LIBOR
Consolidated debt obligations
Spread on variable rate	1.25%
Unsecured Debt | Indenture IB (Preferred Trust I)
Consolidated debt obligations
Principal balance outstanding	$ 25,774,000	25,774,000
Unsecured Debt | Indenture IB (Preferred Trust I) | LIBOR
Consolidated debt obligations
Spread on variable rate	1.25%
Unsecured Debt | Indenture II (Preferred Trust II)
Consolidated debt obligations
Principal balance outstanding	$ 25,774,000	$ 25,774,000
Unsecured Debt | Indenture II (Preferred Trust II) | LIBOR
Consolidated debt obligations
Spread on variable rate	1.25%

Debt Obligations - Textual (Det

Debt Obligations - Textual (Details) - Revolving Credit Facility	9 Months Ended
	Sep. 30, 2021USD ($)
Debt Instrument [Line Items]
Maximum borrowing capacity (up to)	$ 600,000,000
Weighted average interest rate	1.21%
Interest expense, debt	$ 300,000
LIBOR
Debt Instrument [Line Items]
Spread on variable rate	1.10%

Debt Obligations - Aggregate Sc

Debt Obligations - Aggregate Scheduled Principal Payments of Debt Obligation, Excluding Amortization of Discounts and Premiums (Details) $ in Thousands	Sep. 30, 2021USD ($)
Debt Disclosure [Abstract]
2021 (three months remaining)	$ 0
2022	250,000
2023	350,000
2024	350,000
2025	0
Thereafter	878,610
Total principal payments	1,828,610
Net unamortized premiums/(discounts)	8,675
Net deferred financing costs	(6,696)
Debt, net	$ 1,830,589

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Financial Instruments for which Estimates of Fair Value Differ from Carrying Amounts (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred financing costs, net	$ 6,696
Unsecured notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred financing costs, net	6,696	$ 8,152
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable	44,430	94,430
Carrying Amount | Unsecured notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unsecured notes payable	1,502,502	1,502,901
Deferred financing costs, net	6,200	7,200
Carrying Amount | Variable rate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Variable rate debt	328,087	327,694
Deferred financing costs, net	500	900
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, fair value	46,266	97,372
Fair Value | Unsecured notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	1,623,840	1,607,310
Fair Value | Variable rate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	$ 309,523	$ 308,838

Derivative Financial Instrume_3

Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative, notional amount	$ 250,000	$ 275,774
2.868% Interest Rate Swap Maturing October 8, 2022 | Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Derivative liability, notional amount	$ 250,000	250,000
Derivative, fixed interest rate	2.868%
Derivative liability, fair value, gross liability	$ (3,872)	(6,627)
3.300% Interest Rate Swap Maturing January 30, 2021 | Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Derivative liability, notional amount	$ 0	25,774
Derivative, fixed interest rate	3.30%
Derivative liability, fair value, gross liability	$ 0	$ (120)

Limited Partners' Noncontroll_2

Limited Partners' Noncontrolling Interests in the Parent Company (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Noncontrolling Interest [Abstract]
Aggregate amount related to non-controlling interests classified within equity	$ 8.3	$ 10.5
Settlement value of non controlling interest in operating partnership	$ 11.2	$ 11.7

Beneficiaries Equity of the P_3

Beneficiaries Equity of the Parent Company - Number of Shares and Net Income Used to Calculate Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator
Net income	$ 974	$ (175)	$ 6,964	$ 276,133	$ 4,020	$ 8,087	$ 7,763	$ 288,240
Net income attributable to noncontrolling interests	(7)			(1,612)			(42)	(1,701)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(91)			(93)			(331)	(317)
Net income attributable to noncontrolling interests, Diluted	(7)			(1,612)			(42)	(1,701)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(91)			(93)			(331)	(317)
Net income attributable to common shareholders, basic	876			274,428			7,390	286,222
Net income attributable to common shareholders, diluted	$ 876			$ 274,428			$ 7,390	$ 286,222
Denominator
Basic weighted average shares outstanding (in shares)	170,907,018			170,573,028			170,794,585	172,380,410
Contingent securities/Share based compensation (in shares)	1,330,176			453,464			1,283,365	355,026
Diluted weighted average shares outstanding (in shares)	172,237,194			171,026,492			172,077,950	172,735,436
Earnings per Common Share:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.01			$ 1.61			$ 0.04	$ 1.66
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.01			$ 1.60			$ 0.04	$ 1.66

Beneficiaries Equity of the P_4

Beneficiaries Equity of the Parent Company - Textual (Details) - USD ($)	Sep. 14, 2021	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Jan. 03, 2019
Class of Stock [Line Items]
Dividends, common stock	$ 32,800,000
Share repurchase, authorized amount						$ 150,000,000
Shares repurchased and retired (in shares)				0	6,248,483
Share price (in dollars per share)					$ 9.60
Value of stock repurchased and retired		$ 6,141,000	$ 53,858,000		$ 60,000,000
One and Two Commerce Square
Class of Stock [Line Items]
Units issued to acquire noncontrolling interest				226,695
Percent of noncontrolling interest acquired				1.00%
Dividend declared
Class of Stock [Line Items]
Dividends payable (in dollars per share)	$ 0.19
Redeemable Common Limited Partnership Units
Class of Stock [Line Items]
Redeemable common limited partnership units (in shares)				823,983	981,634

Partners' Equity Of The Paren_3

Partners' Equity Of The Parent Company - Number of Units and Net Income Used to Calculate Basic and Diluted Earnings Per Common Partnership Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator
Net income	$ 974	$ (175)	$ 6,964	$ 276,133	$ 4,020	$ 8,087	$ 7,763	$ 288,240
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(91)			(93)			(331)	(317)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (91)			$ (93)			$ (331)	$ (317)
Denominator
Basic weighted average shares outstanding (in shares)	170,907,018			170,573,028			170,794,585	172,380,410
Contingent securities/Share based compensation (in shares)	1,330,176			453,464			1,283,365	355,026
Diluted weighted average shares outstanding (in shares)	172,237,194			171,026,492			172,077,950	172,735,436
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.01			$ 1.61			$ 0.04	$ 1.66
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.01			$ 1.60			$ 0.04	$ 1.66
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Net income	$ 974	$ (175)	$ 6,964	$ 276,133	$ 4,020	$ 8,087	$ 7,763	$ 288,240
Net (income) loss attributable to noncontrolling interests	2			2			4	(20)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(91)			(93)			(331)	(317)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(91)			(93)			(331)	(317)
Net income (loss) attributable to common unitholders, Basic	885			276,042			7,436	287,903
Net income (loss) attributable to common unitholders, Diluted	$ 885			$ 276,042			$ 7,436	$ 287,903
Denominator
Basic weighted average shares outstanding (in shares)	171,731,001			171,554,662			171,710,387	173,362,044
Contingent securities/Share based compensation (in shares)	1,330,176			453,464			1,283,365	355,026
Diluted weighted average shares outstanding (in shares)	173,061,177			172,008,126			172,993,752	173,717,070
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.01			$ 1.61			$ 0.04	$ 1.66
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.01			$ 1.60			$ 0.04	$ 1.66

Partners' Equity Of The Paren_4

Partners' Equity Of The Parent Company - Textual (Details) $ / shares in Units, $ in Thousands	Sep. 14, 2021USD ($)$ / shares	May 18, 2021USD ($)$ / shares	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Sep. 30, 2021shares	Sep. 30, 2020USD ($)$ / sharesshares
Earnings Per Common Partnership Unit [Line Items]
Dividends, common stock | $	$ 32,800
Shares repurchased and retired (in units) | shares					0	6,248,483
Share price (in dollars per unit) | $ / shares						$ 9.60
Value of stock repurchased and retired | $			$ 6,141	$ 53,858		$ 60,000
Shelf Registration
Earnings Per Common Partnership Unit [Line Items]
Number of shares issued (in units) | shares					226,695
One and Two Commerce Square
Earnings Per Common Partnership Unit [Line Items]
Percent of noncontrolling interest acquired					1.00%
Dividend declared
Earnings Per Common Partnership Unit [Line Items]
Dividends payable (in dollars per unit) | $ / shares	$ 0.19
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings Per Common Partnership Unit [Line Items]
Dividends, common stock | $		$ 32,800
Repurchase program, ratio of mirror unit of operating partnership retired for each common share repurchased					1
BRANDYWINE OPERATING PARTNERSHIP, L.P. | Dividend declared
Earnings Per Common Partnership Unit [Line Items]
Dividends payable (in dollars per unit) | $ / shares		$ 0.19

Segment Information (Textual) (

Segment Information (Textual) (Details)	9 Months Ended
	Sep. 30, 2021segment
Segment Reporting [Abstract]
Number of reportable segments	5

Segment Information - Real Esta

Segment Information - Real Estate Investments, at Cost of Company's Reportable Segments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating properties	$ 3,437,074	$ 3,474,109
Right of use asset - operating leases, net	20,478	20,977
Construction-in-progress	266,263	210,311
Land held for development	118,684	117,984
Prepaid leasehold interests in land held for development, net	27,762	39,185
Philadelphia CBD
Segment Reporting Information [Line Items]
Operating properties	1,430,724	1,433,927
Pennsylvania Suburbs
Segment Reporting Information [Line Items]
Operating properties	875,586	871,530
Austin, Texas
Segment Reporting Information [Line Items]
Operating properties	771,977	728,741
Metropolitan Washington, D.C.
Segment Reporting Information [Line Items]
Operating properties	271,929	352,794
Other
Segment Reporting Information [Line Items]
Operating properties	$ 86,858	$ 87,117

Segment Information - Net Opera

Segment Information - Net Operating Income of Company's Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Total revenue	$ 120,418	$ 126,106	$ 361,289	$ 408,031
Operating expenses	(47,052)	(48,999)	(141,153)	(158,391)
Net operating income (loss)	73,366	77,107	220,136	249,640
Operating Segments | Philadelphia CBD
Segment Reporting Information [Line Items]
Total revenue	51,587	52,640	154,259	181,203
Operating expenses	(18,823)	(18,522)	(54,493)	(65,615)
Net operating income (loss)	32,764	34,118	99,766	115,588
Operating Segments | Pennsylvania Suburbs
Segment Reporting Information [Line Items]
Total revenue	31,327	34,649	93,361	106,569
Operating expenses	(10,154)	(11,141)	(30,625)	(34,980)
Net operating income (loss)	21,173	23,508	62,736	71,589
Operating Segments | Austin, Texas
Segment Reporting Information [Line Items]
Total revenue	24,813	25,328	76,501	76,921
Operating expenses	(9,580)	(9,944)	(29,262)	(30,032)
Net operating income (loss)	15,233	15,384	47,239	46,889
Operating Segments | Metropolitan Washington, D.C.
Segment Reporting Information [Line Items]
Total revenue	5,224	9,675	14,711	30,520
Operating expenses	(3,806)	(5,236)	(11,907)	(15,678)
Net operating income (loss)	1,418	4,439	2,804	14,842
Operating Segments | Other
Segment Reporting Information [Line Items]
Total revenue	3,638	3,188	10,513	10,221
Operating expenses	(2,534)	(2,374)	(7,344)	(7,434)
Net operating income (loss)	1,104	814	3,169	2,787
Corporate
Segment Reporting Information [Line Items]
Total revenue	3,829	626	11,944	2,597
Operating expenses	(2,155)	(1,782)	(7,522)	(4,652)
Net operating income (loss)	$ 1,674	$ (1,156)	$ 4,422	$ (2,055)

Segment Information - Unconsoli

Segment Information - Unconsolidated Real Estate Ventures of Company's Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Investment in real estate ventures	$ 427,411		$ 427,411		$ 389,811
Equity in income (loss) of real estate venture	(6,634)	$ (5,788)	(20,798)	$ (9,882)
Philadelphia CBD
Segment Reporting Information [Line Items]
Investment in real estate ventures	319,645		319,645		268,562
Equity in income (loss) of real estate venture	(3,602)	(2,737)	(12,542)	(2,576)
Metropolitan Washington, D.C.
Segment Reporting Information [Line Items]
Investment in real estate ventures	97,972		97,972		99,769
Equity in income (loss) of real estate venture	(1,173)	(1,367)	(2,368)	(2,463)
Mid-Atlantic Office Joint Venture
Segment Reporting Information [Line Items]
Investment in real estate ventures	32,041		32,041		32,996
Equity in income (loss) of real estate venture	310	0	634	0
MAP Venture
Segment Reporting Information [Line Items]
Investment in real estate ventures	(22,247)		(22,247)		$ (11,516)
Equity in income (loss) of real estate venture	$ (2,169)	$ (1,684)	$ (6,522)	$ (4,843)

Segment Information - Reconcili

Segment Information - Reconciliation of Consolidated Net Income to Consolidated NOI (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting [Abstract]
Net income	$ 974	$ (175)	$ 6,964	$ 276,133	$ 4,020	$ 8,087	$ 7,763	$ 288,240
Plus:
Interest expense	15,190			16,310			46,973	56,510
Interest expense - amortization of deferred financing costs	709			715			2,127	2,195
Depreciation and amortization	48,175			43,533			131,303	145,314
General and administrative expenses	7,076			7,069			22,016	23,973
Equity in loss of unconsolidated real estate ventures	6,634			5,788			20,798	9,882
Less:
Interest and investment income	4,494			467			7,845	1,487
Income tax (provision) benefit	(12)			(2)			(46)	224
Net gain on disposition of real estate	0			271,901			142	274,487
Net gain on sale of undepreciated real estate	910			0			2,903	201
Net gain on real estate venture transactions	0			75			0	75
Consolidated net operating income	$ 73,366			$ 77,107			$ 220,136	$ 249,640

Commitments and Contingencies (

Commitments and Contingencies (Details)	1 Months Ended	9 Months Ended
	Feb. 28, 2021property	Sep. 30, 2021USD ($)	Jul. 23, 2021
Property Subject to or Available for Operating Lease [Line Items]
Debt, net		$ 1,830,589,000
Limited payment guarantee, percent of principle balance (up to)			25.00%
Winter Storm
Property Subject to or Available for Operating Lease [Line Items]
Number of properties damaged | property	1
Write-off of fixed assets		1,200,000
Restoration liability		7,200,000
Business interruption costs		3,900,000
Insurance proceeds		13,000,000
Winter Storm | Other Income
Property Subject to or Available for Operating Lease [Line Items]
Insurance proceeds		700,000
Winter Storm | Accounts Payable and Accrued Liabilities
Property Subject to or Available for Operating Lease [Line Items]
Restoration liability		2,000,000
One and Two Commerce Square | Preferred Equity Investment
Property Subject to or Available for Operating Lease [Line Items]
Other commitments		20,000,000
Amount committed to date		2,100,000
Drexel Square
Property Subject to or Available for Operating Lease [Line Items]
Other commitments		7,600,000
Estimated potential additional contribution obligation		2,400,000
4040 Wilson Venture
Property Subject to or Available for Operating Lease [Line Items]
Debt, net		150,000,000
Guarantees, maximum exposure amount (up to)		41,300,000
Unconsolidated Real Estate Ventures
Property Subject to or Available for Operating Lease [Line Items]
Real estate ventures aggregate indebtedness		$ 958,800,000