Brandywine Operating Partnership 10-Q 28 Oct 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 21, 2020
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
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 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
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		170,572,964
Entity Central Index Key	0000790816
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false
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, 2020	Dec. 31, 2019
Real estate investments:
Operating properties	$ 3,715,765	$ 4,006,459
Accumulated depreciation	(980,664)	(973,318)
Right of use asset - operating leases, net	21,145	21,656
Operating real estate investments, net	2,756,246	3,054,797
Construction-in-progress	186,853	180,718
Land held for development	115,474	96,124
Prepaid leasehold interests in land held for development, net	39,287	39,592
Total real estate investments, net	3,097,860	3,371,231
Assets held for sale, net	7,349	7,349
Cash and cash equivalents	62,256	90,499
Accounts receivable, net of allowance of $0 and $284 as of September 30, 2020 and December 31, 2019, respectively	20,433	16,363
Accrued rent receivable, net of allowance of $6,111 and $7,691 as of September 30, 2020 and December 31, 2019, respectively	159,952	174,144
Investment in Real Estate Ventures	377,486	120,294
Deferred costs, net	90,601	95,560
Intangible assets, net	50,715	84,851
Other assets	124,408	115,678
Total assets	3,991,060	4,075,969
LIABILITIES AND EQUITY
Mortgage notes payable, net	88,913	313,812
Unsecured term loan, net	248,953	248,561
Unsecured senior notes, net	1,581,645	1,582,045
Accounts payable and accrued expenses	117,248	113,347
Distributions payable	32,705	33,815
Deferred income, gains and rent	25,070	35,284
Intangible liabilities, net	17,500	22,263
Lease liability - operating leases	22,707	22,554
Other liabilities	40,537	15,985
Total liabilities	2,175,278	2,387,666
Commitments and contingencies (See Note 14)
Equity:
Common Shares of Brandywine Realty Trust's beneficial interest, $0.01 par value; shares authorized 400,000,000; 170,572,964 and 176,480,095 issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	1,707	1,766
Additional paid-in-capital	3,136,851	3,192,158
Deferred compensation payable in common shares	17,516	16,216
Common shares in grantor trust, 1,160,494 and 1,105,542 issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	(17,516)	(16,216)
Cumulative earnings	1,091,095	804,556
Accumulated other comprehensive loss	(8,749)	(2,370)
Cumulative distributions	(2,415,736)	(2,318,233)
Total Brandywine Realty Trust's equity	1,805,168	1,677,877
Noncontrolling interests	10,614	10,426
Total beneficiaries' equity	1,815,782	1,688,303
Total liabilities and beneficiaries' equity	3,991,060	4,075,969
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Operating properties	3,715,765	4,006,459
Accumulated depreciation	(980,664)	(973,318)
Right of use asset - operating leases, net	21,145	21,656
Operating real estate investments, net	2,756,246	3,054,797
Construction-in-progress	186,853	180,718
Land held for development	115,474	96,124
Prepaid leasehold interests in land held for development, net	39,287	39,592
Total real estate investments, net	3,097,860	3,371,231
Assets held for sale, net	7,349	7,349
Cash and cash equivalents	62,256	90,499
Accounts receivable, net of allowance of $0 and $284 as of September 30, 2020 and December 31, 2019, respectively	20,433	16,363
Accrued rent receivable, net of allowance of $6,111 and $7,691 as of September 30, 2020 and December 31, 2019, respectively	159,952	174,144
Investment in Real Estate Ventures	377,486	120,294
Deferred costs, net	90,601	95,560
Intangible assets, net	50,715	84,851
Other assets	124,408	115,678
Total assets	3,991,060	4,075,969
LIABILITIES AND EQUITY
Mortgage notes payable, net	88,913	313,812
Unsecured term loan, net	248,953	248,561
Unsecured senior notes, net	1,581,645	1,582,045
Accounts payable and accrued expenses	117,248	113,347
Distributions payable	32,705	33,815
Deferred income, gains and rent	25,070	35,284
Intangible liabilities, net	17,500	22,263
Lease liability - operating leases	22,707	22,554
Other liabilities	40,537	15,985
Total liabilities	2,175,278	2,387,666
Commitments and contingencies (See Note 14)
Redeemable limited partnership units at redemption value; 981,634 issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	9,950	15,388
Equity:
General Partnership Capital; 170,572,964 and 176,480,095 units issued and outstanding as of September 30, 2020 and December 31, 2019, respectively	1,814,890	1,674,539
Accumulated other comprehensive loss	(9,130)	(2,715)
Total Brandywine Operating Partnership, L.P.'s equity	1,805,760	1,671,824
Noncontrolling interest - consolidated real estate ventures	72	1,091
Total partners' equity	1,805,832	1,672,915
Total liabilities and beneficiaries' equity	$ 3,991,060	$ 4,075,969

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts receivable, allowance	$ 0	$ 284
Accrued rent receivable, allowance	$ 6,111	$ 7,691
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)	170,572,964	176,480,095
Common stock, shares outstanding (in shares)	170,572,964	176,480,095
Common shares in grantor trust, issued and outstanding (in shares)	1,160,494	1,105,542
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Accounts receivable, allowance	$ 0	$ 284
Accrued rent receivable, allowance	$ 6,111	$ 7,691
Redeemable limited partnership units issued (in units)	981,634	981,634
Redeemable limited partnership units outstanding (in units)	981,634	981,634
General partners' capital account, units issued (in units)	170,572,964	176,480,095
General partners' capital account, units outstanding (in units)	170,572,964	176,480,095

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue
Revenue	$ 126,106	$ 145,331	$ 408,031	$ 433,378
Operating expenses
Property operating expenses	31,567	38,358	102,320	116,542
Real estate taxes	14,923	15,247	48,525	47,119
Third party management expenses	2,509	2,469	7,546	7,035
Depreciation and amortization	43,533	55,627	145,314	158,738
General and administrative expenses	7,069	6,974	23,973	25,217
Total operating expenses	99,601	118,675	327,678	354,651
Gain on sale of real estate
Net gain on disposition of real estate	271,901	356	274,487	356
Net gain on sale of undepreciated real estate	0	250	201	1,501
Total gain on sale of real estate	271,901	606	274,688	1,857
Operating income	298,406	27,262	355,041	80,584
Other income (expense):
Interest income	467	558	1,487	1,636
Interest expense	(16,310)	(20,400)	(56,510)	(61,273)
Interest expense - amortization of deferred financing costs	(715)	(694)	(2,195)	(2,026)
Equity in loss of Real Estate Ventures	(5,788)	(1,965)	(9,882)	(4,814)
Net gain on real estate venture transactions	75	2,059	75	3,594
Net income before income taxes	276,135	6,820	288,016	17,701
Income tax (provision) benefit	(2)	0	224	(46)
Net income	276,133	6,820	288,240	17,655
Net income attributable to noncontrolling interests	(1,612)	(48)	(1,701)	(155)
Net income attributable to Brandywine Realty Trust	274,521	6,772	286,539	17,500
Nonforfeitable dividends allocated to unvested restricted shareholders	(93)	(93)	(317)	(305)
Net income attributable to Common Shareholders of Brandywine Realty Trust	$ 274,428	$ 6,679	$ 286,222	$ 17,195
Basic income per Common Share (in dollars per share)	$ 1.61	$ 0.04	$ 1.66	$ 0.10
Diluted income per Common Share (in dollars per share)	$ 1.60	$ 0.04	$ 1.66	$ 0.10
Basic weighted average shares outstanding (in shares)	170,573,028	176,195,244	172,380,410	176,066,507
Diluted weighted average shares outstanding (in shares)	171,026,492	176,750,600	172,735,436	176,617,726
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Revenue	$ 126,106	$ 145,331	$ 408,031	$ 433,378
Operating expenses
Property operating expenses	31,567	38,358	102,320	116,542
Real estate taxes	14,923	15,247	48,525	47,119
Third party management expenses	2,509	2,469	7,546	7,035
Depreciation and amortization	43,533	55,627	145,314	158,738
General and administrative expenses	7,069	6,974	23,973	25,217
Total operating expenses	99,601	118,675	327,678	354,651
Gain on sale of real estate
Net gain on disposition of real estate	271,901	356	274,487	356
Net gain on sale of undepreciated real estate	0	250	201	1,501
Total gain on sale of real estate	271,901	606	274,688	1,857
Operating income	298,406	27,262	355,041	80,584
Other income (expense):
Interest income	467	558	1,487	1,636
Interest expense	(16,310)	(20,400)	(56,510)	(61,273)
Interest expense - amortization of deferred financing costs	(715)	(694)	(2,195)	(2,026)
Equity in loss of Real Estate Ventures	(5,788)	(1,965)	(9,882)	(4,814)
Net gain on real estate venture transactions	75	2,059	75	3,594
Net income before income taxes	276,135	6,820	288,016	17,701
Income tax (provision) benefit	(2)	0	224	(46)
Net income	276,133	6,820	288,240	17,655
Net (income) loss attributable to noncontrolling interests - consolidated real estate ventures	2	(11)	(20)	(58)
Net income attributable to Brandywine Operating Partnership	276,135	6,809	288,220	17,597
Nonforfeitable dividends allocated to unvested restricted shareholders	(93)	(93)	(317)	(305)
Net income attributable to Common Shareholders of Brandywine Realty Trust	$ 276,042	$ 6,716	$ 287,903	$ 17,292
Basic income per Common Share (in dollars per share)	$ 1.61	$ 0.04	$ 1.66	$ 0.10
Diluted income per Common Share (in dollars per share)	$ 1.60	$ 0.04	$ 1.66	$ 0.10
Basic weighted average shares outstanding (in shares)	171,554,662	177,176,870	173,362,044	177,048,621
Diluted weighted average shares outstanding (in shares)	172,008,126	177,732,226	173,717,070	177,599,840
Rents
Revenue
Revenue	$ 121,277	$ 139,228	$ 392,661	$ 415,113
Rents | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Revenue	121,277	139,228	392,661	415,113
Third party management fees, labor reimbursement and leasing
Revenue
Service and other revenue	4,324	4,938	13,339	14,041
Third party management fees, labor reimbursement and leasing | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Service and other revenue	4,324	4,938	13,339	14,041
Other
Revenue
Service and other revenue	505	1,165	2,031	4,224
Other | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Service and other revenue	$ 505	$ 1,165	$ 2,031	$ 4,224

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income		$ 276,133	$ 6,820	$ 288,240	$ 17,655
Comprehensive income (loss):
Unrealized gain (loss) on derivative financial instruments		1,040	(1,586)	(6,979)	(9,209)
Amortization of interest rate contracts	[1]	188	188	564	582
Total comprehensive income (loss)		1,228	(1,398)	(6,415)	(8,627)
Comprehensive income		277,361	5,422	281,825	9,028
Comprehensive income attributable to noncontrolling interest		(1,619)	(40)	(1,665)	(107)
Comprehensive income attributable to Brandywine Realty Trust		275,742	5,382	280,160	8,921
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Net income		276,133	6,820	288,240	17,655
Comprehensive income (loss):
Unrealized gain (loss) on derivative financial instruments		1,040	(1,586)	(6,979)	(9,209)
Amortization of interest rate contracts	[1]	188	188	564	582
Total comprehensive income (loss)		1,228	(1,398)	(6,415)	(8,627)
Comprehensive income		277,361	5,422	281,825	9,028
Comprehensive income attributable to noncontrolling interest		2	(11)	(20)	(58)
Comprehensive income attributable to Brandywine Realty Trust		$ 277,363	$ 5,411	$ 281,805	$ 8,970
[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	Cumulative effect of accounting change	Cumulative effect of accounting changeCumulative Earnings
Beginning balance (in shares) at Dec. 31, 2018		176,873,324	977,120
Beginning balance at Dec. 31, 2018	$ 1,811,028	$ 1,770	$ 14,021	$ 3,200,312	$ (14,021)	$ 775,625	$ 5,029	$ (2,183,909)	$ 12,201	$ (5,336)	$ (5,336)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	4,583					4,523			60
Other comprehensive income (loss)	(2,483)						(2,469)		(14)
Issuance of partnership interest in consolidated real estate ventures	22								22
Repurchase and retirement of Common Shares of Beneficial Interest (in shares)		(1,337,169)
Repurchase and retirement of Common Shares of Beneficial Interest	(17,281)	$ (13)		(17,268)
Share-based compensation activity (in shares)		465,883	41,342
Share-based compensation activity	3,677	$ 4		3,673
Share Issuance from/(to) Deferred Compensation Plan (in shares)		(458)	(5,920)
Share Issuance from/(to) Deferred Compensation Plan	0		$ 619		(619)
Reallocation of Noncontrolling interest	0			57					(57)
Distributions declared	(33,747)							(33,560)	(187)
Ending balance (in shares) at Mar. 31, 2019		176,001,580	1,012,542
Ending balance at Mar. 31, 2019	1,760,463	$ 1,761	$ 14,640	3,186,774	(14,640)	774,812	2,560	(2,217,469)	12,025
Beginning balance (in shares) at Dec. 31, 2018		176,873,324	977,120
Beginning balance at Dec. 31, 2018	1,811,028	$ 1,770	$ 14,021	3,200,312	(14,021)	775,625	5,029	(2,183,909)	12,201	$ (5,336)	$ (5,336)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	17,655
Other comprehensive income (loss)	$ (8,627)
Repurchase and retirement of Common Shares of Beneficial Interest (in shares)	(1,337,169)
Repurchase and retirement of Common Shares of Beneficial Interest	$ (17,300)
Ending balance (in shares) at Sep. 30, 2019		176,194,918	1,105,542
Ending balance at Sep. 30, 2019	1,702,437	$ 1,763	$ 16,216	3,189,350	(16,216)	787,789	(3,550)	(2,284,610)	11,695
Beginning balance (in shares) at Mar. 31, 2019		176,001,580	1,012,542
Beginning balance at Mar. 31, 2019	1,760,463	$ 1,761	$ 14,640	3,186,774	(14,640)	774,812	2,560	(2,217,469)	12,025
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	6,252					6,205			47
Other comprehensive income (loss)	(4,746)						(4,720)		(26)
Issuance of partnership interest in consolidated real estate ventures	3								3
Redemption of LP Units (in shares)		1,245
Redemption of LP Units	0			16					(16)
Share-based compensation activity (in shares)		94,150
Share-based compensation activity	1,451	$ 2		1,449
Share Issuance from/(to) Deferred Compensation Plan (in shares)		100,908	100,908
Share Issuance from/(to) Deferred Compensation Plan	0		$ 1,599		(1,599)
Distributions declared	(33,758)							(33,571)	(187)
Ending balance (in shares) at Jun. 30, 2019		176,197,883	1,113,450
Ending balance at Jun. 30, 2019	1,729,665	$ 1,763	$ 16,239	3,188,239	(16,239)	781,017	(2,160)	(2,251,040)	11,846
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	6,820					6,772			48
Other comprehensive income (loss)	(1,398)						(1,390)		(8)
Issuance of partnership interest in consolidated real estate ventures	2								2
Share-based compensation activity	1,105			1,105
Share Issuance from/(to) Deferred Compensation Plan (in shares)		(2,965)	(7,908)
Share Issuance from/(to) Deferred Compensation Plan	0		$ (23)		23
Reallocation of Noncontrolling interest	0			6					(6)
Distributions declared	(33,757)							(33,570)	(187)
Ending balance (in shares) at Sep. 30, 2019		176,194,918	1,105,542
Ending balance at Sep. 30, 2019	1,702,437	$ 1,763	$ 16,216	3,189,350	(16,216)	787,789	(3,550)	(2,284,610)	11,695
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	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	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	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	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

Consolidated Statements of Be_2

Consolidated Statements of Beneficiaries' Equity (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
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 Interests	BRANDYWINE OPERATING PARTNERSHIP, L.P.	BRANDYWINE OPERATING PARTNERSHIP, L.P.Accumulated Other Comprehensive Income (Loss)	BRANDYWINE OPERATING PARTNERSHIP, L.P.Noncontrolling Interests	BRANDYWINE OPERATING PARTNERSHIP, L.P.General Partner Capital	BRANDYWINE OPERATING PARTNERSHIP, L.P.Cumulative effect of accounting change	BRANDYWINE OPERATING PARTNERSHIP, L.P.Cumulative effect of accounting changeGeneral Partner Capital
Beginning balance (in shares) at Dec. 31, 2018							176,873,324
Beginning Balance at Dec. 31, 2018				$ 1,798,508	$ 4,725	$ 2,192	$ 1,791,591	$ (5,336)	$ (5,336)
Net income	$ 4,583		$ 60	4,583		34	$ 4,549
Other comprehensive income (loss)	(2,483)	$ (2,469)	(14)	(2,483)	(2,483)
Deferred compensation obligation (in shares)							(458)
Deferred compensation obligation	0			0
Repurchase and retirement of LP units (in shares)							(1,337,169)
Repurchase and retirement of LP units				(17,281)			$ (17,281)
Issuance of partnership interest in consolidated real estate ventures	22		22	22		22
Share-based compensation activity (in shares)							465,883
Share-based compensation activity	3,677			3,677			$ 3,677
Adjustment of redeemable partnership units to liquidation value at period end				(3,088)			(3,088)
Distributions declared to general partnership unitholders				(33,560)			$ (33,560)
Ending balance (in shares) at Mar. 31, 2019							176,001,580
Ending Balance at Mar. 31, 2019				1,745,042	2,242	2,248	$ 1,740,552
Beginning balance (in shares) at Dec. 31, 2018							176,873,324
Beginning Balance at Dec. 31, 2018				1,798,508	4,725	2,192	$ 1,791,591	$ (5,336)	$ (5,336)
Net income	17,655			17,655
Other comprehensive income (loss)	(8,627)			(8,627)
Ending balance (in shares) at Sep. 30, 2019							176,194,918
Ending Balance at Sep. 30, 2019				1,687,709	(3,902)	2,277	$ 1,689,334
Beginning balance (in shares) at Mar. 31, 2019							176,001,580
Beginning Balance at Mar. 31, 2019				1,745,042	2,242	2,248	$ 1,740,552
Net income	6,252		47	6,252		13	$ 6,239
Other comprehensive income (loss)	(4,746)	(4,720)	(26)	(4,746)	(4,746)
Deferred compensation obligation (in shares)							100,908
Deferred compensation obligation	0			0
Repurchase and retirement of LP units (in shares)							1,245
Repurchase and retirement of LP units				0
Issuance of partnership interest in consolidated real estate ventures	3		3	3		3
Share-based compensation activity (in shares)							94,150
Share-based compensation activity	1,451			1,451			$ 1,451
Adjustment of redeemable partnership units to liquidation value at period end				1,014			1,014
Distributions declared to general partnership unitholders				(33,571)			$ (33,571)
Ending balance (in shares) at Jun. 30, 2019							176,197,883
Ending Balance at Jun. 30, 2019				1,715,445	(2,504)	2,264	$ 1,715,685
Net income	6,820		48	6,820		11	$ 6,809
Other comprehensive income (loss)	(1,398)	(1,390)	(8)	(1,398)	(1,398)
Deferred compensation obligation (in shares)							(2,965)
Deferred compensation obligation	0			0
Issuance of partnership interest in consolidated real estate ventures	2		2	2		2
Share-based compensation activity	1,105			1,105			$ 1,105
Adjustment of redeemable partnership units to liquidation value at period end				(695)			(695)
Distributions declared to general partnership unitholders				(33,570)			$ (33,570)
Ending balance (in shares) at Sep. 30, 2019							176,194,918
Ending Balance at Sep. 30, 2019				1,687,709	(3,902)	2,277	$ 1,689,334
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	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	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	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	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

Consolidated Statements of Pa_2

Consolidated Statements of Partners' Equity (Parenthetical) - $ / shares	3 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
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, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 288,240	$ 17,655
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	145,314	158,738
Amortization of deferred financing costs	2,195	2,026
Amortization of debt discount/(premium), net	(55)	527
Amortization of stock compensation costs	5,544	6,145
Straight-line rent income	(8,903)	(8,287)
Amortization of acquired above (below) market leases, net	(3,657)	(7,236)
Ground rent expense	1,092	1,103
Provision for doubtful accounts	1,041	611
Net gain on real estate venture transactions	0	(3,594)
Net gain on sale of interests in real estate	(274,688)	(1,857)
Loss from Real Estate Ventures, net of distributions	9,880	5,134
Income tax provision (benefit)	(224)	46
Changes in assets and liabilities:
Accounts receivable	(6,263)	2,086
Other assets	(7,527)	(13,089)
Accounts payable and accrued expenses	10,782	194
Deferred income, gains and rent	(8,856)	(3,640)
Other liabilities	8,549	(1,312)
Net cash provided by operating activities	162,464	155,250
Cash flows from investing activities:
Acquisition of properties	(11,432)	0
Proceeds from the sale of properties	122,055	41,546
Proceeds from real estate venture sales	0	675
Proceeds from repayment of mortgage notes receivable	0	3,341
Capital expenditures for tenant improvements	(55,262)	(53,383)
Capital expenditures for redevelopments	(18,664)	(33,905)
Capital expenditures for developments	(51,435)	(55,002)
Advances for the purchase of tenant assets, net of repayments	1,265	(178)
Investment in unconsolidated Real Estate Ventures	(719)	(253)
Deposits for real estate	0	(1,990)
Capital distributions from Real Estate Ventures	6,916	35,206
Leasing costs paid	(16,747)	(13,184)
Net cash used in investing activities	(24,023)	(77,127)
Cash flows from financing activities:
Repayments of mortgage notes payable	(6,105)	(5,669)
Proceeds from credit facility borrowings	170,500	333,000
Repayments of credit facility borrowings	(170,500)	(279,000)
Proceeds from the exercise of stock options	47	800
Shares used for employee taxes upon vesting of share awards	(1,346)	(1,554)
Partner contributions to consolidated real estate venture	0	25
Repurchase and retirement of common shares	(60,000)	(17,282)
Distributions paid to shareholders	(98,651)	(100,573)
Distributions to noncontrolling interest	(561)	(560)
Net cash used in financing activities	(166,616)	(70,813)
Increase/(Decrease) in cash and cash equivalents and restricted cash	(28,175)	7,310
Cash and cash equivalents and restricted cash at beginning of year	91,170	23,211
Cash and cash equivalents and restricted cash at end of period	62,995	30,521
Reconciliation of cash and cash equivalents and restricted cash:
Cash and cash equivalents, beginning of period	90,499	22,842
Restricted cash, beginning of period	671	369
Cash and cash equivalents and restricted cash at beginning of year	91,170	23,211
Cash and cash equivalents, end of period	62,256	29,925
Restricted cash, end of period	739	596
Cash and cash equivalents and restricted cash at end of period	62,995	30,521
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the nine months ended September 30, 2020 and 2019 of $3,462 and $2,246, respectively	51,733	56,455
Cash paid for income taxes	719	1,169
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	32,705	33,759
Change in investment in real estate ventures as a result of dispositions	0	3,461
Change in operating real estate from deconsolidation of operating properties	269,268	0
Change in investment in real estate ventures from deconsolidation of operating properties	(263,358)	0
Change in mortgage notes payable from deconsolidation of operating properties	(220,271)	0
Change in capital expenditures financed through accounts payable at period end	(8,244)	(6,011)
Change in capital expenditures financed through retention payable at period end	754	(3,356)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Cash flows from operating activities:
Net income	288,240	17,655
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	145,314	158,738
Amortization of deferred financing costs	2,195	2,026
Amortization of debt discount/(premium), net	(55)	527
Amortization of stock compensation costs	5,544	6,145
Straight-line rent income	(8,903)	(8,287)
Amortization of acquired above (below) market leases, net	(3,657)	(7,236)
Ground rent expense	1,092	1,103
Provision for doubtful accounts	1,041	611
Net gain on real estate venture transactions	0	(3,594)
Net gain on sale of interests in real estate	(274,688)	(1,857)
Loss from Real Estate Ventures, net of distributions	9,880	5,134
Income tax provision (benefit)	(224)	46
Changes in assets and liabilities:
Accounts receivable	(6,263)	2,086
Other assets	(7,527)	(13,089)
Accounts payable and accrued expenses	10,782	194
Deferred income, gains and rent	(8,856)	(3,640)
Other liabilities	8,549	(1,312)
Net cash provided by operating activities	162,464	155,250
Cash flows from investing activities:
Acquisition of properties	(11,432)	0
Proceeds from the sale of properties	122,055	41,546
Proceeds from real estate venture sales	0	675
Proceeds from repayment of mortgage notes receivable	0	3,341
Capital expenditures for tenant improvements	(55,262)	(53,383)
Capital expenditures for redevelopments	(18,664)	(33,905)
Capital expenditures for developments	(51,435)	(55,002)
Advances for the purchase of tenant assets, net of repayments	1,265	(178)
Investment in unconsolidated Real Estate Ventures	(719)	(253)
Deposits for real estate	0	(1,990)
Capital distributions from Real Estate Ventures	6,916	35,206
Leasing costs paid	(16,747)	(13,184)
Net cash used in investing activities	(24,023)	(77,127)
Cash flows from financing activities:
Repayments of mortgage notes payable	(6,105)	(5,669)
Proceeds from credit facility borrowings	170,500	333,000
Repayments of credit facility borrowings	(170,500)	(279,000)
Proceeds from the exercise of stock options	47	800
Shares used for employee taxes upon vesting of share awards	(1,346)	(1,554)
Partner contributions to consolidated real estate venture	0	25
Repurchase and retirement of common shares	(60,000)	(17,282)
Distributions paid to shareholders	(99,212)	(101,133)
Net cash used in financing activities	(166,616)	(70,813)
Increase/(Decrease) in cash and cash equivalents and restricted cash	(28,175)	7,310
Cash and cash equivalents and restricted cash at beginning of year	91,170	23,211
Cash and cash equivalents and restricted cash at end of period	62,995	30,521
Reconciliation of cash and cash equivalents and restricted cash:
Cash and cash equivalents, beginning of period	90,499	22,842
Restricted cash, beginning of period	671	369
Cash and cash equivalents and restricted cash at beginning of year	91,170	23,211
Cash and cash equivalents, end of period	62,256	29,925
Restricted cash, end of period	739	596
Cash and cash equivalents and restricted cash at end of period	62,995	30,521
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the nine months ended September 30, 2020 and 2019 of $3,462 and $2,246, respectively	51,733	56,455
Cash paid for income taxes	719	1,169
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	32,705	33,759
Change in investment in real estate ventures as a result of dispositions	0	3,461
Change in operating real estate from deconsolidation of operating properties	269,268	0
Change in investment in real estate ventures from deconsolidation of operating properties	(263,358)	0
Change in mortgage notes payable from deconsolidation of operating properties	(220,271)	0
Change in capital expenditures financed through accounts payable at period end	(8,244)	(6,011)
Change in capital expenditures financed through retention payable at period end	$ 754	$ (3,356)

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Capitalized interest	$ 3,462	$ 2,246
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Capitalized interest	$ 3,462	$ 2,246

Organization of the Parent Comp

Organization of the Parent Company and The Operating Partnership	9 Months Ended
	Sep. 30, 2020
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, 2020 , owned a 99.4% 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, 2020 , the Company owned 92 properties that contained an aggregate of approximately 14.7 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, 2020 : Number of Properties Rentable Square Feet Office properties 84 13,641,289 Mixed-use properties 5 780,184 Core Properties 89 14,421,473 Development property 1 205,803 Redevelopment properties 2 64,070 The Properties 92 14,691,346 In addition to the Properties, as of September 30, 2020 , the Company owned 228.5 acres of land held for development, of which 35.2 acres were held for sale. The Company also held leasehold interests in two land parcels totaling 1.8 acres, each acquired through prepaid 99 -year ground leases, and held options to purchase approximately 55.5 additional acres of undeveloped land. As of September 30, 2020 , 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 14.2 million square feet, of which 0.2 million square feet relates to 35.2 acres held for sale. As of September 30, 2020 , the Company also owned economic interests in eight unconsolidated real estate ventures (collectively, the “Real Estate Ventures”) (see Note 4, ''Investment in Unconsolidated Real Estate Ventures ” for further information). The Properties and the properties owned by the Real Estate Ventures are 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, 2020 , the management company subsidiaries were managing properties containing an aggregate of approximately 24.4 million net rentable square feet, of which approximately 14.7 million net rentable square feet related to Properties owned by the Company and approximately 9.7 million net rentable square feet related to properties owned by third parties and 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, 2020
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, 2020 , the results of its operations for the three and nine months ended September 30, 2020 and 2019 and its cash flows for the nine months ended September 30, 2020 and 2019 . 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 2019 Annual Report on Form 10-K filed with the SEC on March 2, 2020. The consolidated balance sheet at December 31, 2019 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, 2019 contains a discussion of our significant accounting policies under Note 2, "Summary of Significant Accounting Policies" . There have been no significant changes in our significant accounting policies since December 31, 2019 . Risks and Uncertainties - COVID-19 Currently, one of the most significant risks and uncertainties is the potential adverse effect of the ongoing global COVID-19 pandemic, which has significantly slowed global economic activity, caused significant volatility in financial markets, and resulted in unprecedented job losses, causing many to fear an imminent global recession. The responses of many countries, including the U.S., have included mandatory quarantines, restrictions on business activities, including construction activities, restrictions on group gatherings, restrictions on travel and mandatory closures. These actions are creating disruption in the global economy and supply chains and adversely impacting many industries, including owners and developers of real estate. Moreover, there is significant uncertainty around the breadth and duration of business disruptions related to COVID-19, as well as its impact on the U.S. economy and consumer confidence. Demand for space at our properties is dependent on a variety of macroeconomic factors, such as employment levels, interest rates, changes in stock market valuations, rent levels and availability of competing space. The extent to which COVID-19 impacts our results will depend on future developments, many of which are highly uncertain and cannot be predicted, including new information which may emerge concerning the severity of COVID-19 and future action plans. The COVID-19 pandemic has caused continued negative economic impacts, market volatility, and business disruption, which could negatively impact our tenants’ ability to pay rent, our ability to lease vacant space, and our ability to complete development and redevelopment projects. These consequences, in turn, could materially impact our results of operations. Accounting Standards Updates In May 2020, the SEC adopted amendments to requirements for companies relating to significant acquisitions and dispositions of businesses as well as amendments to the significance tests in the ‘significant subsidiary’ definition. Additionally, significant modifications were made to the requirements related to the presentation of pro forma financial information. The amendments are effective on January 1, 2021, with early adoption permitted. The Company has elected to early adopt the amendments as of September 30, 2020. On April 10, 2020, the Financial Accounting Standards Board (the "FASB") issued a Staff Q&A to respond to some frequently asked questions about accounting for lease concessions related to the effects of the COVID-19 pandemic. Consequently, for concessions related to the effects of the COVID-19 pandemic, an entity will not have to analyze each contract to determine whether enforceable rights and obligations for concessions exist in the contract and can elect to apply or not apply the lease modification guidance to those contracts. Entities may make the elections for any lessor-provided concessions related to the effects of the COVID-19 pandemic (e.g., deferrals of lease payments, cash payments made to the lessee, reduced future lease payments) as long as the concession does not result in a substantial increase in the rights of the lessor or the obligations of the lessee. The Company has elected to account for lease concessions as though the enforceable rights and obligations for the concessions existed in the original lease. To date, the impact of lease concessions granted has not had a material effect on the financial statements. The Company will continue to evaluate the impact of lease concessions and the appropriate accounting for those concessions. 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. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments Credit Losses (Topic 326), which changes how entities measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance replaces the current incurred loss model with an expected loss approach, resulting in more timely recognition of such losses. In November 2018, the FASB released ASU 2018-19, Codification Improvements to Topic 326, Financial Instrument - Credit Losses, which clarifies that receivables arising from operating leases are not within the scope of Subtopic 326-20. The guidance was effective for the Company as of January 1, 2020. The Company adopted ASU 2016-13 effective January 1, 2020 and it did not have a material impact on the consolidated financial statements.

Real Estate Investments

Real Estate Investments	9 Months Ended
	Sep. 30, 2020
Real Estate [Abstract]
REAL ESTATE INVESTMENTS	3. REAL ESTATE INVESTMENTS As of September 30, 2020 and December 31, 2019 , the gross carrying value of the operating properties was as follows (in thousands): September 30, 2020 December 31, 2019 Land $ 437,617 $ 489,702 Building and improvements 2,851,185 3,049,395 Tenant improvements 426,963 467,362 Total $ 3,715,765 $ 4,006,459 Acquisitions The following table summarizes the property acquisitions during the nine months ended September 30, 2020 (dollars in thousands): Property/Portfolio Name Acquisition Date Location Property Type Rentable Square Feet/Acres Purchase Price 145 King of Prussia Road February 27, 2020 Radnor, PA Land 7.75 acres $ 11,250 Dispositions The following table summarizes the property dispositions during the nine months ended September 30, 2020 (dollars in thousands): Property/Portfolio Name Disposition Date Location Property Type Rentable Square Feet/Acres Sales Price Gain/(Loss) on Sale (a) 52 East Swedesford Road March 19, 2020 Malvern, PA Office 131,077 $ 18,000 $ 2,336 Keith Valley June 15, 2020 Horsham, PA Land 14.0 Acres $ 4,000 $ 201 One and Two Commerce Square (b) July 21, 2020 Philadelphia, PA Office 1,896,142 $ 115,000 $ 271,905 (a) Gain/(Loss) on Sale is net of closing and other transaction related costs. (b) The Company sold a preferred equity interest representing a 30% equity interest in two office buildings located in Philadelphia, Pennsylvania, to an unrelated third party for $115.0 million (the "Commerce Square Venture Transaction"), which resulted in deconsolidation of the properties and formation of Brandywine Commerce I LP and Brandywine Commerce II LP (collectively, the "Commerce Square Venture"). The transaction valued the properties at $600.0 million . The Company recorded its investment at fair value and recognized a gain of $271.9 million in "Net gain on disposition of real estate" on the Consolidated Statements of Operations during the three months ended September 30, 2020. See Note 4, ''Investment in Unconsolidated Real Estate Ventures ," for further information. Held for Sale As of September 30, 2020 and December 31, 2019, the Company determined that the sale of two parcels of land within the Other segment totaling 35.2 acres was probable and classified these properties as held for sale. As such, $7.3 million

Investment in Unconsolidated Re

Investment in Unconsolidated Real Estate Ventures	9 Months Ended
	Sep. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES	4. INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES As of September 30, 2020 , the Company held ownership interests in eight unconsolidated real estate ventures for a net aggregate investment balance of $367.8 million , which includes a negative investment balance in one unconsolidated real estate venture of $9.7 million , reflected within "Other liabilities" on the consolidated balance sheets. As of September 30, 2020 , four of the real estate ventures owned properties that contained an aggregate of approximately 7.3 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 1.3 acres of land in active development; and one real estate venture owned a residential tower that contained 321 apartment units. The Company accounts for its interests in the Real Estate Ventures, which range from 15% to 70% , using the equity method. Certain of the Real Estate Ventures are subject to specified priority allocations of distributable cash. The Company earned management fees from its Real Estate Ventures of $1.3 million and $3.2 million for the three and nine months ended September 30, 2020 , respectively, and $1.0 million and $3.2 million for the three and nine months ended September 30, 2019 , respectively. The Company earned leasing commission income from its Real Estate Ventures of $0.2 million and $0.9 million for the three and nine months ended September 30, 2020 , respectively, and $0.3 million and $0.8 million for the three and nine months ended September 30, 2019 , respectively. The Company had outstanding accounts receivable balances from its Real Estate Ventures of $1.4 million and $0.8 million as of September 30, 2020 and December 31, 2019 , 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 Real Estate Ventures. The following is a summary of the financial position of the Real Estate Ventures in which the Company held interests as of September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 December 31, 2019 Net property $ 1,363,889 $ 834,367 Other assets 442,834 342,002 Other liabilities 323,442 290,071 Debt, net 833,716 585,068 Equity (a) 649,565 301,230 (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 Real Estate Ventures in which the Company held interests during the three and nine -month periods ended September 30, 2020 and 2019 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Revenue $ 43,109 $ 32,726 $ 105,554 $ 101,148 Operating expenses (23,870 ) (17,869 ) (59,838 ) (53,956 ) Interest expense, net (6,175 ) (6,180 ) (16,320 ) (16,421 ) Depreciation and amortization (22,345 ) (13,094 ) (47,493 ) (40,279 ) Gain on early extinguishment of debt — 4,371 — 4,371 Net loss $ (9,281 ) $ (46 ) $ (18,097 ) $ (5,137 ) Ownership interest % Various Various Various Various Company's share of net income (loss) $ (5,812 ) $ (1,945 ) $ (9,892 ) $ (4,765 ) Basis adjustments and other 24 (20 ) 10 (49 ) Equity in loss of Real Estate Ventures $ (5,788 ) $ (1,965 ) $ (9,882 ) $ (4,814 ) Commerce Square Venture On July 21, 2020, the Company sold a 30% preferred equity interest in the entities that own One Commerce Square and Two Commerce Square. After the transaction, the Company owns approximately 32% of the equity interest in Commerce Square Venture through preferred equity interest holdings and approximately 38% of the equity interest in Commerce Square Venture as the sole common equity holder, for a combined approximately 70% equity interest in the venture. The properties held by the newly formed joint ventures remain encumbered by the existing mortgages, which had a $222.1 million principal balance outstanding on the transaction date. Based on the facts and circumstances at the formation of the Commerce Square Venture, the Company determined that the venture is not a variable interest entity. As a result, the Company used the voting interest model under the accounting standard for consolidation in order to determine whether to consolidate the Commerce Square Venture. Based upon each member's substantive participating rights over the activities of the Commerce Square Venture under the operating and related agreements of the Commerce Square Venture, the Company does not have a controlling interest in the properties as the third party investor holds substantive participating rights in the properties. Therefore, the Company deconsolidated the properties and the venture is accounted for under the equity method of accounting. As a result, the Company measured its equity interest at fair value based on the fair value of the Commerce Square Venture properties and the distribution provisions of the real estate venture agreement. Since the Company retains a non-controlling interest in the Commerce Square Venture and there are no other facts and circumstances that preclude sale recognition, the contribution qualifies as the sale of a nonfinancial asset under the relevant guidance. Under the conventional approach of accounting for equity method investments, an investor applies its percentage ownership interest to the venture’s net income or loss to determine the investor’s share of the earnings or losses of the venture. This approach is inappropriate if the venture’s capital structure gives different rights and priorities to its investors. Therefore, the Company follows the hypothetical liquidation at book value (“HLBV”) method in determining its share of the venture’s earnings or losses for the reporting period as this method better reflects the Company’s claim on the venture’s book value at the end of each reporting period. Earnings for this equity method investment are recognized in accordance with the investment agreement and, where applicable, based upon the allocation of the investment’s net assets at book value as if the investment was hypothetically liquidated at the end of each reporting period.

Leases

Leases	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
LEASES	5. 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, 2020 and 2019 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Lease Revenue 2020 2019 2020 2019 Fixed contractual payments $ 95,751 $ 105,073 $ 302,146 $ 314,999 Variable lease payments 22,716 27,475 80,824 83,989 Total $ 118,467 $ 132,548 $ 382,970 $ 398,988

Intangible Assets and Liabiliti

Intangible Assets and Liabilities	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS AND LIABILITIES	6. INTANGIBLE ASSETS AND LIABILITIES As of September 30, 2020 and December 31, 2019 , the Company’s intangible assets/liabilities were comprised of the following (in thousands): September 30, 2020 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 89,504 $ (39,302 ) $ 50,202 Tenant relationship value 2,610 (2,399 ) 211 Above market leases acquired 1,140 (838 ) 302 Total intangible assets, net $ 93,254 $ (42,539 ) $ 50,715 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 29,189 $ (11,689 ) $ 17,500 December 31, 2019 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 167,357 $ (84,123 ) $ 83,234 Tenant relationship value 5,268 (4,815 ) 453 Above market leases acquired 4,956 (3,792 ) 1,164 Total intangible assets, net $ 177,581 $ (92,730 ) $ 84,851 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 44,757 $ (22,494 ) $ 22,263 As of September 30, 2020 , the Company’s annual amortization for its intangible assets/liabilities, assuming no prospective early lease terminations, was as follows (dollars in thousands): Assets Liabilities 2020 (three months remaining) $ 4,273 $ 1,011 2021 14,789 3,601 2022 9,627 2,065 2023 7,564 1,651 2024 5,214 1,425 Thereafter 9,248 7,747 Total $ 50,715 $ 17,500

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
DEBT OBLIGATIONS	7. DEBT OBLIGATIONS The following table sets forth information regarding the Company’s consolidated debt obligations outstanding as of September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 December 31, 2019 Effective Interest Rate Maturity Date MORTGAGE DEBT: Two Logan Square (a) $ 79,781 $ 81,103 3.98% October 2020 Four Tower Bridge 9,107 9,291 4.50% February 2021 One Commerce Square (b) — 116,571 3.64% April 2023 Two Commerce Square (b) — 108,472 4.51% April 2023 Principal balance outstanding 88,888 315,437 Plus: fair market value premium (discount), net 25 (1,383 ) Less: deferred financing costs — (242 ) Mortgage indebtedness $ 88,913 $ 313,812 UNSECURED DEBT Seven-Year Term Loan - Swapped to fixed $ 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) - Swapped to fixed 25,774 25,774 3.30% 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 10,626 12,090 Less: deferred financing costs (8,638 ) (10,094 ) Total unsecured indebtedness $ 1,830,598 $ 1,830,606 Total Debt Obligations $ 1,919,511 $ 2,144,418 (a) On October 21, 2020, the Company acquired the mortgage on this property from the lender. See Note 15, "Subsequent Events," for further information. (b) The properties encumbered by these mortgages were deconsolidated as a result of the Commerce Square Venture Transaction.. See Note 3, ''Real Estate Investments ," for further information. In addition to the debt described above, 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, 2020 , the weighted-average interest rate on Unsecured Credit Facility borrowings was 1.6% resulting in a nominal amount of interest expense. As of September 30, 2020 , the Company had no borrowings under the Unsecured Credit Facility. 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, 2020 . Certain of the covenants restrict the Company’s ability to obtain alternative sources of capital. As of September 30, 2020 , the Company’s aggregate scheduled principal payments of debt obligations are as follows (in thousands): 2020 (three months remaining) $ 79,845 2021 9,043 2022 250,000 2023 350,000 2024 350,000 Thereafter 878,610 Total principal payments 1,917,498 Net unamortized premiums/(discounts) 10,651 Net deferred financing costs (8,638 ) Outstanding indebtedness $ 1,919,511

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	8. 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, 2020 and December 31, 2019 , 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, 2020 and December 31, 2019 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, 2020 December 31, 2019 Carrying Amount (a) Fair Value Carrying Amount (a) Fair Value Unsecured notes payable $ 1,503,035 $ 1,566,650 $ 1,503,435 $ 1,591,830 Variable rate debt $ 327,563 $ 308,519 $ 327,171 $ 309,947 Mortgage notes payable $ 88,913 $ 89,034 $ 313,812 $ 317,031 Notes receivable $ 44,430 $ 47,415 $ 44,430 $ 43,322 (a) Net of deferred financing costs of $7.6 million and $8.7 million for unsecured notes payable, $1.0 million and $1.4 million for variable rate debt and $0.0 million and $0.2 million for mortgage notes payable as of September 30, 2020 and December 31, 2019 . On June 26, 2018, the Company provided a $44.4 million mortgage loan to Brandywine 1919 Ventures, an unconsolidated real estate venture in which the Company holds a 50% ownership interest, and recorded a related party note receivable of $44.4 million within 'Other assets' on the consolidated balance sheets. Refer to Note 4, ''Investment in Unconsolidated Real Estate Ventures " to the consolidated financial statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 for further detail regarding this financing. The Company used quoted market prices as of September 30, 2020 and December 31, 2019 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 mortgage notes payable and 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 fair value of the mortgage notes payable was determined using a discounted cash flow model that considered the contractual interest and principal payments discounted at a blended market rate for loans with similar terms, maturities and loan-to-value. These inputs have been categorized as Level 3 because the Company considers the rates used in the valuation techniques to be unobservable. 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, 2020 and December 31, 2019 . 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, 2020 . Current estimates of fair value may differ from the amounts presented herein.

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	9. DERIVATIVE FINANCIAL INSTRUMENTS The following table summarizes the terms and fair values of the Company’s derivative financial instruments as of September 30, 2020 and December 31, 2019 . 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 9/30/2020 12/31/2019 9/30/2020 12/31/2019 Liabilities Swap Interest Rate Cash Flow (a) $ 250,000 $ 250,000 2.868 % October 8, 2015 October 8, 2022 $ (7,597 ) $ (562 ) Swap Interest Rate Cash Flow (a) 25,774 25,774 3.300 % December 22, 2011 January 30, 2021 (234 ) (94 ) $ 275,774 $ 275,774 (a) Hedging unsecured variable rate debt. 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, 2020 and December 31, 2019 . 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, 2020 . Current estimates of fair value may differ from the amounts presented herein.

Limited Partners' Non-Controlli

Limited Partners' Non-Controlling Interests in the Parent Company	9 Months Ended
	Sep. 30, 2020
Noncontrolling Interest [Abstract]
LIMITED PARTNERS' NON-CONTROLLING INTERESTS IN THE PARENT COMPANY	10. 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 $10.5 million and $9.3 million as of September 30, 2020 and December 31, 2019 , 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 closing price of the common shares on the balance sheet date) was approximately $10.2 million and $15.5 million as of September 30, 2020 and December 31, 2019 , respectively.

Beneficiaries Equity of the Par

Beneficiaries Equity of the Parent Company	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
BENEFICIARIES' EQUITY OF THE PARENT COMPANY	11. 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, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 276,133 $ 276,133 $ 6,820 $ 6,820 Net income attributable to noncontrolling interests (1,612 ) (1,612 ) (48 ) (48 ) Nonforfeitable dividends allocated to unvested restricted shareholders (93 ) (93 ) (93 ) (93 ) Net income attributable to common shareholders $ 274,428 $ 274,428 $ 6,679 $ 6,679 Denominator Weighted-average shares outstanding 170,573,028 170,573,028 176,195,244 176,195,244 Contingent securities/Share based compensation — 453,464 — 555,356 Weighted-average shares outstanding 170,573,028 171,026,492 176,195,244 176,750,600 Earnings per Common Share: Net income attributable to common shareholders $ 1.61 $ 1.60 $ 0.04 $ 0.04 Nine Months Ended September 30, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 288,240 $ 288,240 $ 17,655 $ 17,655 Net income attributable to noncontrolling interests (1,701 ) (1,701 ) (155 ) (155 ) Nonforfeitable dividends allocated to unvested restricted shareholders (317 ) (317 ) (305 ) (305 ) Net income attributable to common shareholders $ 286,222 $ 286,222 $ 17,195 $ 17,195 Denominator Weighted-average shares outstanding 172,380,410 172,380,410 176,066,507 176,066,507 Contingent securities/Share based compensation — 355,026 — 551,219 Weighted-average shares outstanding 172,380,410 172,735,436 176,066,507 176,617,726 Earnings per Common Share: Net income attributable to common shareholders $ 1.66 $ 1.66 $ 0.10 $ 0.10 Redeemable common limited partnership units totaling 981,634 at September 30, 2020 and 981,626 at September 30, 2019 , 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, 2020 and 2019 , 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 15, 2020 the Parent Company declared a distribution of $0.19 per common share, totaling $32.7 million , which was paid on October 21, 2020 to shareholders of record as of October 7, 2020. 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, 2020 , the Company repurchased and retired 6,248,483 common shares at an average price of $9.60 per share, totaling $60.0 million . During the nine months ended September 30, 2019 , the Company repurchased and retired 1,337,169 common shares at an average price of $12.92 per share, totaling $17.3 million .

Partners' Equity Of The Parent

Partners' Equity Of The Parent Company	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
PARTNERS' EQUITY OF THE PARENT COMPANY	12. 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, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 276,133 $ 276,133 $ 6,820 $ 6,820 Net (income) loss attributable to noncontrolling interests 2 2 (11 ) (11 ) Nonforfeitable dividends allocated to unvested restricted unitholders (93 ) (93 ) (93 ) (93 ) Net income attributable to common unitholders $ 276,042 $ 276,042 $ 6,716 $ 6,716 Denominator Weighted-average units outstanding 171,554,662 171,554,662 177,176,870 177,176,870 Contingent securities/Share based compensation — 453,464 — 555,356 Total weighted-average units outstanding 171,554,662 172,008,126 177,176,870 177,732,226 Earnings per Common Partnership Unit: Net income attributable to common unitholders 1.61 1.60 0.04 0.04 Nine Months Ended September 30, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 288,240 $ 288,240 $ 17,655 $ 17,655 Net income attributable to noncontrolling interests (20 ) (20 ) (58 ) (58 ) Nonforfeitable dividends allocated to unvested restricted unitholders (317 ) (317 ) (305 ) (305 ) Net income attributable to common unitholders $ 287,903 $ 287,903 $ 17,292 $ 17,292 Denominator Weighted-average units outstanding 173,362,044 173,362,044 177,048,621 177,048,621 Contingent securities/Share based compensation — 355,026 — 551,219 Total weighted-average units outstanding 173,362,044 173,717,070 177,048,621 177,599,840 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 1.66 $ 1.66 $ 0.10 $ 0.10 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, 2020 and 2019 , 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 15, 2020 the Operating Partnership declared a distribution of $0.19 per common partnership unit, totaling $32.7 million , which was paid on October 21, 2020 to unitholders of record as of October 7, 2020. 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, 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 common share repurchases. During the nine months ended September 30, 2019 , the Company retired 1,337,169 common partnership units at an average price of $12.92 per unit, totaling $17.3 million

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
SEGMENT INFORMATION	13. SEGMENT INFORMATION As of September 30, 2020 , 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, 2020 December 31, 2019 Philadelphia CBD (a) $ 1,414,041 $ 1,726,299 Pennsylvania Suburbs 1,000,214 1,003,890 Austin, Texas 726,295 721,255 Metropolitan Washington, D.C. 488,139 468,035 Other 87,076 86,980 Operating Properties $ 3,715,765 $ 4,006,459 Right of use asset - operating leases, net $ 21,145 $ 21,656 Corporate Construction-in-progress $ 186,853 $ 180,718 Land held for development (b) $ 115,474 $ 96,124 Prepaid leasehold interests in land held for development, net (c) $ 39,287 $ 39,592 (a) Decrease primarily due to the Commerce Square Venture Transaction. See Note 3, ''Real Estate Investments ," for further information. (b) Does not include 35.2 acres of land classified as held for sale as of September 30, 2020 and December 31, 2019 . (c) Includes leasehold interests in prepaid 99 -year ground leases at 3025 and 3001-3003 JFK Boulevard, in Philadelphia, Pennsylvania as of September 30, 2020 and December 31, 2019 . Net operating income: Three Months Ended September 30, 2020 2019 Total revenue Operating expenses (a) Net operating income (loss) Total revenue Operating expenses (a) Net operating income (loss) Philadelphia CBD $ 52,640 $ (18,522 ) $ 34,118 $ 66,105 $ (24,773 ) $ 41,332 Pennsylvania Suburbs 34,649 (11,141 ) 23,508 34,818 (11,667 ) 23,151 Austin, Texas 25,328 (9,944 ) 15,384 26,280 (9,302 ) 16,978 Metropolitan Washington, D.C. 9,675 (5,236 ) 4,439 13,179 (5,999 ) 7,180 Other 3,188 (2,374 ) 814 3,706 (2,691 ) 1,015 Corporate 626 (1,782 ) (1,156 ) 1,243 (1,642 ) (399 ) Operating properties $ 126,106 $ (48,999 ) $ 77,107 $ 145,331 $ (56,074 ) $ 89,257 Nine Months Ended September 30, 2020 2019 Total revenue Operating expenses (a) Net operating income (loss) Total revenue Operating expenses (a) Net operating income (loss) Philadelphia CBD $ 181,203 $ (65,615 ) $ 115,588 $ 196,859 $ (75,311 ) 121,548 Pennsylvania Suburbs 106,569 (34,980 ) 71,589 104,744 (36,466 ) 68,278 Austin, Texas 76,921 (30,032 ) 46,889 77,234 (28,182 ) 49,052 Metropolitan Washington, D.C. 30,520 (15,678 ) 14,842 40,372 (18,542 ) 21,830 Other 10,221 (7,434 ) 2,787 10,352 (7,226 ) 3,126 Corporate 2,597 (4,652 ) (2,055 ) 3,817 (4,969 ) (1,152 ) Operating properties $ 408,031 $ (158,391 ) $ 249,640 $ 433,378 $ (170,696 ) $ 262,682 (a) Includes property operating expenses, real estate taxes and third party management expense. 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, 2020 December 31, 2019 2020 2019 2020 2019 Philadelphia CBD (a) $ 277,161 $ 17,524 $ (2,737 ) $ 55 $ (2,575 ) $ 217 Metropolitan Washington, D.C. 100,325 102,840 (1,367 ) (528 ) (2,463 ) (963 ) MAP Venture (b) (9,715 ) (70 ) (1,684 ) (1,602 ) (4,844 ) (4,414 ) Other — — — 110 — 346 Total $ 367,771 $ 120,294 $ (5,788 ) $ (1,965 ) $ (9,882 ) $ (4,814 ) (a) Increase primarily due to the Commerce Square Venture Transaction. See Note 3, ''Real Estate Investments ," for further information. (b) Included in "Other liabilities" on the consolidated balance sheets. 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 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, 2020 2019 2020 2019 Net income $ 276,133 $ 6,820 $ 288,240 $ 17,655 Plus: Interest expense 16,310 20,400 56,510 61,273 Interest expense - amortization of deferred financing costs 715 694 2,195 2,026 Depreciation and amortization 43,533 55,627 145,314 158,738 General and administrative expenses 7,069 6,974 23,973 25,217 Equity in loss of Real Estate Ventures 5,788 1,965 9,882 4,814 Less: Interest income 467 558 1,487 1,636 Income tax (provision) benefit (2 ) — 224 (46 ) Net gain on disposition of real estate 271,901 356 274,487 356 Net gain on sale of undepreciated real estate — 250 201 1,501 Net gain on real estate venture transactions 75 2,059 75 3,594 Consolidated net operating income $ 77,107 $ 89,257 $ 249,640 $ 262,682

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	14. 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. Letters-of-Credit Under certain mortgages, the Company has funded required leasing and capital reserve accounts for the benefit of the mortgage lenders with letters-of-credit. There were no letters-of-credit for a mortgage lender as of September 30, 2020 . Certain of the tenant rents at properties that secure these mortgage loans are deposited into the loan servicer’s depository accounts, which are used to fund debt service, operating expenses, capital expenditures and the escrow and reserve accounts, as necessary. Any excess cash is included in cash and cash equivalents. 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, 2020 , the Company’s Real Estate Ventures had aggregate indebtedness of $842.2 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, 2020 , 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 Real Estate Ventures, including 4040 Wilson, the Company has provided, and expects to continue to provide, cost overrun and completion guarantees, with rights of contribution among partners or members in the real estate ventures, as well as customary environmental indemnities and guarantees of customary exceptions to nonrecourse provisions in loan agreements. Other Commitments or Contingencies In connection with the Schuylkill Yards Project, the Company entered into a neighborhood engagement program and, as of September 30, 2020 , had $7.7 million of future fixed contractual obligations. The Company also committed to fund additional contributions under the program. As of September 30, 2020 , the Company estimates that these additional contributions, which are not fixed under the terms of agreement, will be $2.6 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. As of September 30, 2020 , the Company was under contract to acquire an office property containing approximately 170,000 rentable square feet located in Radnor, Pennsylvania for a purchase price of $20.3 million . The Company has paid $1.0 million towards the purchase price in the form of a non-refundable deposit and the transaction is expected to close during the fourth quarter of 2020. 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.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	15. SUBSEQUENT EVENTS On October 21, 2020, the Company acquired the $79.8 million

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2020
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, 2020 , the results of its operations for the three and nine months ended September 30, 2020 and 2019 and its cash flows for the nine months ended September 30, 2020 and 2019 . 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 2019 Annual Report on Form 10-K filed with the SEC on March 2, 2020. The consolidated balance sheet at December 31, 2019 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, 2019 contains a discussion of our significant accounting policies under Note 2, "Summary of Significant Accounting Policies" . There have been no significant changes in our significant accounting policies since December 31, 2019 .
Significant Risks and Uncertainties	Risks and Uncertainties - COVID-19 Currently, one of the most significant risks and uncertainties is the potential adverse effect of the ongoing global COVID-19 pandemic, which has significantly slowed global economic activity, caused significant volatility in financial markets, and resulted in unprecedented job losses, causing many to fear an imminent global recession. The responses of many countries, including the U.S., have included mandatory quarantines, restrictions on business activities, including construction activities, restrictions on group gatherings, restrictions on travel and mandatory closures. These actions are creating disruption in the global economy and supply chains and adversely impacting many industries, including owners and developers of real estate. Moreover, there is significant uncertainty around the breadth and duration of business disruptions related to COVID-19, as well as its impact on the U.S. economy and consumer confidence. Demand for space at our properties is dependent on a variety of macroeconomic factors, such as employment levels, interest rates, changes in stock market valuations, rent levels and availability of competing space. The extent to which COVID-19 impacts our results will depend on future developments, many of which are highly uncertain and cannot be predicted, including new information which may emerge concerning the severity of COVID-19 and future action plans. The COVID-19 pandemic has caused continued negative economic impacts, market volatility, and business disruption, which could negatively impact our tenants’ ability to pay rent, our ability to lease vacant space, and our ability to complete development and redevelopment projects. These consequences, in turn, could materially impact our results of operations.
Adoption of New Accounting Guidance	Accounting Standards Updates In May 2020, the SEC adopted amendments to requirements for companies relating to significant acquisitions and dispositions of businesses as well as amendments to the significance tests in the ‘significant subsidiary’ definition. Additionally, significant modifications were made to the requirements related to the presentation of pro forma financial information. The amendments are effective on January 1, 2021, with early adoption permitted. The Company has elected to early adopt the amendments as of September 30, 2020. On April 10, 2020, the Financial Accounting Standards Board (the "FASB") issued a Staff Q&A to respond to some frequently asked questions about accounting for lease concessions related to the effects of the COVID-19 pandemic. Consequently, for concessions related to the effects of the COVID-19 pandemic, an entity will not have to analyze each contract to determine whether enforceable rights and obligations for concessions exist in the contract and can elect to apply or not apply the lease modification guidance to those contracts. Entities may make the elections for any lessor-provided concessions related to the effects of the COVID-19 pandemic (e.g., deferrals of lease payments, cash payments made to the lessee, reduced future lease payments) as long as the concession does not result in a substantial increase in the rights of the lessor or the obligations of the lessee. The Company has elected to account for lease concessions as though the enforceable rights and obligations for the concessions existed in the original lease. To date, the impact of lease concessions granted has not had a material effect on the financial statements. The Company will continue to evaluate the impact of lease concessions and the appropriate accounting for those concessions. 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. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments Credit Losses (Topic 326), which changes how entities measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The guidance replaces the current incurred loss model with an expected loss approach, resulting in more timely recognition of such losses. In November 2018, the FASB released ASU 2018-19, Codification Improvements to Topic 326, Financial Instrument - Credit Losses, which clarifies that receivables arising from operating leases are not within the scope of Subtopic 326-20. The guidance was effective for the Company as of January 1, 2020. The Company adopted ASU 2016-13 effective January 1, 2020 and it did not have a material impact on the consolidated financial statements.

Organization of the Parent Co_2

Organization of the Parent Company and The Operating Partnership (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 : Number of Properties Rentable Square Feet Office properties 84 13,641,289 Mixed-use properties 5 780,184 Core Properties 89 14,421,473 Development property 1 205,803 Redevelopment properties 2 64,070 The Properties 92 14,691,346

Real Estate Investments (Tables

Real Estate Investments (Tables)	9 Months Ended
	Sep. 30, 2020
Real Estate [Abstract]
Gross Carrying Value of Operating Properties	As of September 30, 2020 and December 31, 2019 , the gross carrying value of the operating properties was as follows (in thousands): September 30, 2020 December 31, 2019 Land $ 437,617 $ 489,702 Building and improvements 2,851,185 3,049,395 Tenant improvements 426,963 467,362 Total $ 3,715,765 $ 4,006,459
Summary of Properties Acquired	The following table summarizes the property acquisitions during the nine months ended September 30, 2020 (dollars in thousands): Property/Portfolio Name Acquisition Date Location Property Type Rentable Square Feet/Acres Purchase Price 145 King of Prussia Road February 27, 2020 Radnor, PA Land 7.75 acres $ 11,250
Summary of Properties Sold	The following table summarizes the property dispositions during the nine months ended September 30, 2020 (dollars in thousands): Property/Portfolio Name Disposition Date Location Property Type Rentable Square Feet/Acres Sales Price Gain/(Loss) on Sale (a) 52 East Swedesford Road March 19, 2020 Malvern, PA Office 131,077 $ 18,000 $ 2,336 Keith Valley June 15, 2020 Horsham, PA Land 14.0 Acres $ 4,000 $ 201 One and Two Commerce Square (b) July 21, 2020 Philadelphia, PA Office 1,896,142 $ 115,000 $ 271,905 (a) Gain/(Loss) on Sale is net of closing and other transaction related costs. (b) The Company sold a preferred equity interest representing a 30% equity interest in two office buildings located in Philadelphia, Pennsylvania, to an unrelated third party for $115.0 million (the "Commerce Square Venture Transaction"), which resulted in deconsolidation of the properties and formation of Brandywine Commerce I LP and Brandywine Commerce II LP (collectively, the "Commerce Square Venture"). The transaction valued the properties at $600.0 million . The Company recorded its investment at fair value and recognized a gain of $271.9 million in "Net gain on disposition of real estate" on the Consolidated Statements of Operations during the three months ended September 30, 2020. See Note 4, ''Investment in Unconsolidated Real Estate Ventures ," for further information.

Investment in Unconsolidated _2

Investment in Unconsolidated Real Estate Ventures (Tables)	9 Months Ended
	Sep. 30, 2020
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 Real Estate Ventures in which the Company held interests as of September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 December 31, 2019 Net property $ 1,363,889 $ 834,367 Other assets 442,834 342,002 Other liabilities 323,442 290,071 Debt, net 833,716 585,068 Equity (a) 649,565 301,230 (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 Real Estate Ventures in which the Company held interests during the three and nine -month periods ended September 30, 2020 and 2019 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2020 2019 2020 2019 Revenue $ 43,109 $ 32,726 $ 105,554 $ 101,148 Operating expenses (23,870 ) (17,869 ) (59,838 ) (53,956 ) Interest expense, net (6,175 ) (6,180 ) (16,320 ) (16,421 ) Depreciation and amortization (22,345 ) (13,094 ) (47,493 ) (40,279 ) Gain on early extinguishment of debt — 4,371 — 4,371 Net loss $ (9,281 ) $ (46 ) $ (18,097 ) $ (5,137 ) Ownership interest % Various Various Various Various Company's share of net income (loss) $ (5,812 ) $ (1,945 ) $ (9,892 ) $ (4,765 ) Basis adjustments and other 24 (20 ) 10 (49 ) Equity in loss of Real Estate Ventures $ (5,788 ) $ (1,965 ) $ (9,882 ) $ (4,814 )

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 and 2019 (in thousands): Three Months Ended September 30, Nine Months Ended September 30, Lease Revenue 2020 2019 2020 2019 Fixed contractual payments $ 95,751 $ 105,073 $ 302,146 $ 314,999 Variable lease payments 22,716 27,475 80,824 83,989 Total $ 118,467 $ 132,548 $ 382,970 $ 398,988

Intangible Assets and Liabili_2

Intangible Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets and Liabilities	As of September 30, 2020 and December 31, 2019 , the Company’s intangible assets/liabilities were comprised of the following (in thousands): September 30, 2020 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 89,504 $ (39,302 ) $ 50,202 Tenant relationship value 2,610 (2,399 ) 211 Above market leases acquired 1,140 (838 ) 302 Total intangible assets, net $ 93,254 $ (42,539 ) $ 50,715 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 29,189 $ (11,689 ) $ 17,500 December 31, 2019 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 167,357 $ (84,123 ) $ 83,234 Tenant relationship value 5,268 (4,815 ) 453 Above market leases acquired 4,956 (3,792 ) 1,164 Total intangible assets, net $ 177,581 $ (92,730 ) $ 84,851 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 44,757 $ (22,494 ) $ 22,263
Summary of Amortization for Intangible Assets and Liabilities	As of September 30, 2020 , the Company’s annual amortization for its intangible assets/liabilities, assuming no prospective early lease terminations, was as follows (dollars in thousands): Assets Liabilities 2020 (three months remaining) $ 4,273 $ 1,011 2021 14,789 3,601 2022 9,627 2,065 2023 7,564 1,651 2024 5,214 1,425 Thereafter 9,248 7,747 Total $ 50,715 $ 17,500

Debt Obligations (Tables)

Debt Obligations (Tables)	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Consolidated debt obligations	The following table sets forth information regarding the Company’s consolidated debt obligations outstanding as of September 30, 2020 and December 31, 2019 (in thousands): September 30, 2020 December 31, 2019 Effective Interest Rate Maturity Date MORTGAGE DEBT: Two Logan Square (a) $ 79,781 $ 81,103 3.98% October 2020 Four Tower Bridge 9,107 9,291 4.50% February 2021 One Commerce Square (b) — 116,571 3.64% April 2023 Two Commerce Square (b) — 108,472 4.51% April 2023 Principal balance outstanding 88,888 315,437 Plus: fair market value premium (discount), net 25 (1,383 ) Less: deferred financing costs — (242 ) Mortgage indebtedness $ 88,913 $ 313,812 UNSECURED DEBT Seven-Year Term Loan - Swapped to fixed $ 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) - Swapped to fixed 25,774 25,774 3.30% 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 10,626 12,090 Less: deferred financing costs (8,638 ) (10,094 ) Total unsecured indebtedness $ 1,830,598 $ 1,830,606 Total Debt Obligations $ 1,919,511 $ 2,144,418 (a) On October 21, 2020, the Company acquired the mortgage on this property from the lender. See Note 15, "Subsequent Events," for further information. (b) The properties encumbered by these mortgages were deconsolidated as a result of the Commerce Square Venture Transaction.. See Note 3, ''Real Estate Investments ," for further information.
Schedule of maturities of long-term debt	As of September 30, 2020 , the Company’s aggregate scheduled principal payments of debt obligations are as follows (in thousands): 2020 (three months remaining) $ 79,845 2021 9,043 2022 250,000 2023 350,000 2024 350,000 Thereafter 878,610 Total principal payments 1,917,498 Net unamortized premiums/(discounts) 10,651 Net deferred financing costs (8,638 ) Outstanding indebtedness $ 1,919,511

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 December 31, 2019 Carrying Amount (a) Fair Value Carrying Amount (a) Fair Value Unsecured notes payable $ 1,503,035 $ 1,566,650 $ 1,503,435 $ 1,591,830 Variable rate debt $ 327,563 $ 308,519 $ 327,171 $ 309,947 Mortgage notes payable $ 88,913 $ 89,034 $ 313,812 $ 317,031 Notes receivable $ 44,430 $ 47,415 $ 44,430 $ 43,322 (a) Net of deferred financing costs of $7.6 million and $8.7 million for unsecured notes payable, $1.0 million and $1.4 million for variable rate debt and $0.0 million and $0.2 million for mortgage notes payable as of September 30, 2020 and December 31, 2019 .

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 and December 31, 2019 . 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 9/30/2020 12/31/2019 9/30/2020 12/31/2019 Liabilities Swap Interest Rate Cash Flow (a) $ 250,000 $ 250,000 2.868 % October 8, 2015 October 8, 2022 $ (7,597 ) $ (562 ) Swap Interest Rate Cash Flow (a) 25,774 25,774 3.300 % December 22, 2011 January 30, 2021 (234 ) (94 ) $ 275,774 $ 275,774 (a) Hedging unsecured variable rate debt.

Beneficiaries Equity of the P_2

Beneficiaries Equity of the Parent Company (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 276,133 $ 276,133 $ 6,820 $ 6,820 Net income attributable to noncontrolling interests (1,612 ) (1,612 ) (48 ) (48 ) Nonforfeitable dividends allocated to unvested restricted shareholders (93 ) (93 ) (93 ) (93 ) Net income attributable to common shareholders $ 274,428 $ 274,428 $ 6,679 $ 6,679 Denominator Weighted-average shares outstanding 170,573,028 170,573,028 176,195,244 176,195,244 Contingent securities/Share based compensation — 453,464 — 555,356 Weighted-average shares outstanding 170,573,028 171,026,492 176,195,244 176,750,600 Earnings per Common Share: Net income attributable to common shareholders $ 1.61 $ 1.60 $ 0.04 $ 0.04 Nine Months Ended September 30, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 288,240 $ 288,240 $ 17,655 $ 17,655 Net income attributable to noncontrolling interests (1,701 ) (1,701 ) (155 ) (155 ) Nonforfeitable dividends allocated to unvested restricted shareholders (317 ) (317 ) (305 ) (305 ) Net income attributable to common shareholders $ 286,222 $ 286,222 $ 17,195 $ 17,195 Denominator Weighted-average shares outstanding 172,380,410 172,380,410 176,066,507 176,066,507 Contingent securities/Share based compensation — 355,026 — 551,219 Weighted-average shares outstanding 172,380,410 172,735,436 176,066,507 176,617,726 Earnings per Common Share: Net income attributable to common shareholders $ 1.66 $ 1.66 $ 0.10 $ 0.10

Partners' Equity Of The Paren_2

Partners' Equity Of The Parent Company (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 276,133 $ 276,133 $ 6,820 $ 6,820 Net income attributable to noncontrolling interests (1,612 ) (1,612 ) (48 ) (48 ) Nonforfeitable dividends allocated to unvested restricted shareholders (93 ) (93 ) (93 ) (93 ) Net income attributable to common shareholders $ 274,428 $ 274,428 $ 6,679 $ 6,679 Denominator Weighted-average shares outstanding 170,573,028 170,573,028 176,195,244 176,195,244 Contingent securities/Share based compensation — 453,464 — 555,356 Weighted-average shares outstanding 170,573,028 171,026,492 176,195,244 176,750,600 Earnings per Common Share: Net income attributable to common shareholders $ 1.61 $ 1.60 $ 0.04 $ 0.04 Nine Months Ended September 30, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 288,240 $ 288,240 $ 17,655 $ 17,655 Net income attributable to noncontrolling interests (1,701 ) (1,701 ) (155 ) (155 ) Nonforfeitable dividends allocated to unvested restricted shareholders (317 ) (317 ) (305 ) (305 ) Net income attributable to common shareholders $ 286,222 $ 286,222 $ 17,195 $ 17,195 Denominator Weighted-average shares outstanding 172,380,410 172,380,410 176,066,507 176,066,507 Contingent securities/Share based compensation — 355,026 — 551,219 Weighted-average shares outstanding 172,380,410 172,735,436 176,066,507 176,617,726 Earnings per Common Share: Net income attributable to common shareholders $ 1.66 $ 1.66 $ 0.10 $ 0.10
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings Per Share (EPS), Basic and Diluted	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, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 276,133 $ 276,133 $ 6,820 $ 6,820 Net (income) loss attributable to noncontrolling interests 2 2 (11 ) (11 ) Nonforfeitable dividends allocated to unvested restricted unitholders (93 ) (93 ) (93 ) (93 ) Net income attributable to common unitholders $ 276,042 $ 276,042 $ 6,716 $ 6,716 Denominator Weighted-average units outstanding 171,554,662 171,554,662 177,176,870 177,176,870 Contingent securities/Share based compensation — 453,464 — 555,356 Total weighted-average units outstanding 171,554,662 172,008,126 177,176,870 177,732,226 Earnings per Common Partnership Unit: Net income attributable to common unitholders 1.61 1.60 0.04 0.04 Nine Months Ended September 30, 2020 2019 Basic Diluted Basic Diluted Numerator Net income $ 288,240 $ 288,240 $ 17,655 $ 17,655 Net income attributable to noncontrolling interests (20 ) (20 ) (58 ) (58 ) Nonforfeitable dividends allocated to unvested restricted unitholders (317 ) (317 ) (305 ) (305 ) Net income attributable to common unitholders $ 287,903 $ 287,903 $ 17,292 $ 17,292 Denominator Weighted-average units outstanding 173,362,044 173,362,044 177,048,621 177,048,621 Contingent securities/Share based compensation — 355,026 — 551,219 Total weighted-average units outstanding 173,362,044 173,717,070 177,048,621 177,599,840 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 1.66 $ 1.66 $ 0.10 $ 0.10

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2020
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, 2020 December 31, 2019 Philadelphia CBD (a) $ 1,414,041 $ 1,726,299 Pennsylvania Suburbs 1,000,214 1,003,890 Austin, Texas 726,295 721,255 Metropolitan Washington, D.C. 488,139 468,035 Other 87,076 86,980 Operating Properties $ 3,715,765 $ 4,006,459 Right of use asset - operating leases, net $ 21,145 $ 21,656 Corporate Construction-in-progress $ 186,853 $ 180,718 Land held for development (b) $ 115,474 $ 96,124 Prepaid leasehold interests in land held for development, net (c) $ 39,287 $ 39,592 (a) Decrease primarily due to the Commerce Square Venture Transaction. See Note 3, ''Real Estate Investments ," for further information. (b) Does not include 35.2 acres of land classified as held for sale as of September 30, 2020 and December 31, 2019 . (c) Includes leasehold interests in prepaid 99 -year ground leases at 3025 and 3001-3003 JFK Boulevard, in Philadelphia, Pennsylvania as of September 30, 2020 and December 31, 2019 . Net operating income: Three Months Ended September 30, 2020 2019 Total revenue Operating expenses (a) Net operating income (loss) Total revenue Operating expenses (a) Net operating income (loss) Philadelphia CBD $ 52,640 $ (18,522 ) $ 34,118 $ 66,105 $ (24,773 ) $ 41,332 Pennsylvania Suburbs 34,649 (11,141 ) 23,508 34,818 (11,667 ) 23,151 Austin, Texas 25,328 (9,944 ) 15,384 26,280 (9,302 ) 16,978 Metropolitan Washington, D.C. 9,675 (5,236 ) 4,439 13,179 (5,999 ) 7,180 Other 3,188 (2,374 ) 814 3,706 (2,691 ) 1,015 Corporate 626 (1,782 ) (1,156 ) 1,243 (1,642 ) (399 ) Operating properties $ 126,106 $ (48,999 ) $ 77,107 $ 145,331 $ (56,074 ) $ 89,257 Nine Months Ended September 30, 2020 2019 Total revenue Operating expenses (a) Net operating income (loss) Total revenue Operating expenses (a) Net operating income (loss) Philadelphia CBD $ 181,203 $ (65,615 ) $ 115,588 $ 196,859 $ (75,311 ) 121,548 Pennsylvania Suburbs 106,569 (34,980 ) 71,589 104,744 (36,466 ) 68,278 Austin, Texas 76,921 (30,032 ) 46,889 77,234 (28,182 ) 49,052 Metropolitan Washington, D.C. 30,520 (15,678 ) 14,842 40,372 (18,542 ) 21,830 Other 10,221 (7,434 ) 2,787 10,352 (7,226 ) 3,126 Corporate 2,597 (4,652 ) (2,055 ) 3,817 (4,969 ) (1,152 ) Operating properties $ 408,031 $ (158,391 ) $ 249,640 $ 433,378 $ (170,696 ) $ 262,682 (a) Includes property operating expenses, real estate taxes and third party management expense. 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, 2020 December 31, 2019 2020 2019 2020 2019 Philadelphia CBD (a) $ 277,161 $ 17,524 $ (2,737 ) $ 55 $ (2,575 ) $ 217 Metropolitan Washington, D.C. 100,325 102,840 (1,367 ) (528 ) (2,463 ) (963 ) MAP Venture (b) (9,715 ) (70 ) (1,684 ) (1,602 ) (4,844 ) (4,414 ) Other — — — 110 — 346 Total $ 367,771 $ 120,294 $ (5,788 ) $ (1,965 ) $ (9,882 ) $ (4,814 ) (a) Increase primarily due to the Commerce Square Venture Transaction. See Note 3, ''Real Estate Investments ," for further information. (b) Included in "Other liabilities" on the consolidated balance sheets.
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, 2020 2019 2020 2019 Net income $ 276,133 $ 6,820 $ 288,240 $ 17,655 Plus: Interest expense 16,310 20,400 56,510 61,273 Interest expense - amortization of deferred financing costs 715 694 2,195 2,026 Depreciation and amortization 43,533 55,627 145,314 158,738 General and administrative expenses 7,069 6,974 23,973 25,217 Equity in loss of Real Estate Ventures 5,788 1,965 9,882 4,814 Less: Interest income 467 558 1,487 1,636 Income tax (provision) benefit (2 ) — 224 (46 ) Net gain on disposition of real estate 271,901 356 274,487 356 Net gain on sale of undepreciated real estate — 250 201 1,501 Net gain on real estate venture transactions 75 2,059 75 3,594 Consolidated net operating income $ 77,107 $ 89,257 $ 249,640 $ 262,682

Organization of The Parent Co_3

Organization of The Parent Company and The Operating Partnership - Textual (Details)	9 Months Ended
	Sep. 30, 2020aft²parcelproperty
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of properties | property	92
Net rentable area (in square feet)	14,691,346
Parent Company
Organization of The Parent Company and The Operating Partnership [Line Items]
Areas of land held for development (in acres) | a	228.5
Area of land held for sale (in acres) | a	35.2
Area of additional undeveloped parcels of land with option to purchase (in acres) | a	55.5
Total potential development capacity (in square feet)	14,200,000
Parent Company | Land Parcel One
Organization of The Parent Company and The Operating Partnership [Line Items]
Lease agreement term	99 years
Parent Company | Land Parcel Two
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)	200,000
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	1.8
Number of parcels of land | parcel	2
Wholly-owned Management Company Subsidiaries
Organization of The Parent Company and The Operating Partnership [Line Items]
Net rentable area (in square feet)	24,400,000
Wholly-owned Management Company Subsidiaries | Wholly Owned Properties
Organization of The Parent Company and The Operating Partnership [Line Items]
Net rentable area (in square feet)	14,700,000
Wholly-owned Management Company Subsidiaries | Partially Owned Properties
Organization of The Parent Company and The Operating Partnership [Line Items]
Net rentable area (in square feet)	9,700,000
Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	99.40%
Unconsolidated Real Estate Ventures | Unconsolidated Properties
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of properties | property	8

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, 2020ft²property
Real Estate Properties [Line Items]
Number of properties | property	92
Net rentable area (in square feet) | ft²	14,691,346
Office properties
Real Estate Properties [Line Items]
Number of properties | property	84
Net rentable area (in square feet) | ft²	13,641,289
Mixed-use properties
Real Estate Properties [Line Items]
Number of properties | property	5
Net rentable area (in square feet) | ft²	780,184
Core Properties
Real Estate Properties [Line Items]
Number of properties | property	89
Net rentable area (in square feet) | ft²	14,421,473
Development property
Real Estate Properties [Line Items]
Number of properties | property	1
Net rentable area (in square feet) | ft²	205,803
Redevelopment properties
Real Estate Properties [Line Items]
Number of properties | property	2
Net rentable area (in square feet) | ft²	64,070

Real Estate Investments - Gross

Real Estate Investments - Gross Carrying Value of Operating Properties (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Real Estate [Abstract]
Land	$ 437,617	$ 489,702
Building and improvements	2,851,185	3,049,395
Tenant improvements	426,963	467,362
Total	$ 3,715,765	$ 4,006,459

Real Estate Investments - Summa

Real Estate Investments - Summary of Properties Acquired (Details) $ in Thousands	Feb. 27, 2020USD ($)a	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)
Real Estate [Line Items]
Purchase price		$ 11,432	$ 0
Land | 145 King of Prussia Road
Real Estate [Line Items]
Area of land (in acres) | a	7.75
Purchase price	$ 11,250

Real Estate Investments - Sum_2

Real Estate Investments - Summary of Properties Sold (Details) $ in Thousands	Jul. 21, 2020USD ($)ft²	Jun. 15, 2020USD ($)a	Mar. 19, 2020USD ($)ft²	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from the sale of properties						$ 122,055	$ 41,546
Gain (loss) on sale				$ 271,901	$ 356	$ 274,487	$ 356
One and Two Commerce Square
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of ownership interest percentage	30.00%
Total sale price for property sold	$ 115,000
Value of properties sold	$ 600,000
Gain on sale				$ 271,900
Office properties | 52 East Swedesford Road
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable area (in square feet) | ft²			131,077
Proceeds from the sale of properties			$ 18,000
Gain (loss) on sale			$ 2,336
Office properties | One and Two Commerce Square
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable area (in square feet) | ft²	1,896,142
Proceeds from the sale of properties	$ 115,000
Gain (loss) on sale	$ 271,905
Land | Keith Valley
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of land (in acres) | a		14
Proceeds from the sale of properties		$ 4,000
Gain (loss) on sale		$ 201

Real Estate Investments - Textu

Real Estate Investments - Textual (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)aparcel	Dec. 31, 2019USD ($)a
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, net | $	$ 7,349	$ 7,349
Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Area of land (in acres) | a	35.2	35.2
Other - Land | Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, net | $	$ 7,300
Other - Land | Held-for-sale | Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of parcels of land | parcel	2
Area of land (in acres) | a	35.2

Investment in Unconsolidated _3

Investment in Unconsolidated Real Estate Ventures - Textual (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)aft²investmentpropertyapartment	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)aft²investmentpropertyapartment	Sep. 30, 2019USD ($)	Jul. 21, 2020USD ($)ft²	Dec. 31, 2019USD ($)
Schedule of Equity Method Investments [Line Items]
Number of properties | property	92		92
Investment in Real Estate Ventures	$ 377,486		$ 377,486			$ 120,294
Accounts receivable	20,433		20,433			16,363
Debt, net	$ 1,919,511		$ 1,919,511			2,144,418
Minimum
Schedule of Equity Method Investments [Line Items]
Ownership percentage	15.00%		15.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Ownership percentage	70.00%		70.00%
Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Accounts receivable	$ 1,400		$ 1,400			800
Real Estate Venture | Management Fees
Schedule of Equity Method Investments [Line Items]
Service and other revenue	1,300	$ 1,000	3,200	$ 3,200
Real Estate Venture | Leasing Commission Income
Schedule of Equity Method Investments [Line Items]
Service and other revenue	200	$ 300	900	$ 800
Unconsolidated Real Estate Ventures
Schedule of Equity Method Investments [Line Items]
Investment in Real Estate Ventures	$ 367,800		$ 367,800
Unconsolidated Real Estate Ventures | Office properties
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | investment	4		4
Rentable area (in square feet) | ft²	7,300,000		7,300,000
Unconsolidated Real Estate Ventures | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Number of properties | property	8		8
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 | investment	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 | investment	1		1
Area of land (in acres) | a	1.3		1.3
Unconsolidated Real Estate Ventures | Residential Tower
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in Real Estate Ventures | investment	1		1
Number of apartment units (in units) | apartment	321		321
One and Two Commerce Square
Schedule of Equity Method Investments [Line Items]
Ownership percentage	70.00%		70.00%
Secured Debt
Schedule of Equity Method Investments [Line Items]
Debt, net	$ 88,913		$ 88,913			$ 313,812
Secured Debt | Philadelphia - Office
Schedule of Equity Method Investments [Line Items]
Debt, net					$ 222,100
Preferred Equity Securities | One and Two Commerce Square
Schedule of Equity Method Investments [Line Items]
Ownership percentage	32.00%		32.00%
Common Equity Securities | One and Two Commerce Square
Schedule of Equity Method Investments [Line Items]
Ownership percentage	38.00%		38.00%
Other Liabilities | Unconsolidated Real Estate Ventures
Schedule of Equity Method Investments [Line Items]
Investment in Real Estate Ventures	$ (9,700)		$ (9,700)
One and Two Commerce Square
Schedule of Equity Method Investments [Line Items]
Sale of ownership interest percentage					30.00%
One and Two Commerce Square | Office properties
Schedule of Equity Method Investments [Line Items]
Rentable area (in square feet) | ft²					1,896,142

Investment in Unconsolidated _4

Investment in Unconsolidated Real Estate Ventures - Summary of Financial Position of Real Estate Ventures (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Net property	$ 3,097,860			$ 3,371,231
Other assets	124,408			115,678
Other liabilities	40,537			15,985
Debt, net	1,919,511			2,144,418
Equity	1,815,782	$ 1,570,849	$ 1,603,814	1,688,303	$ 1,702,437	$ 1,729,665	$ 1,760,463	$ 1,811,028
Investment In Nonconsolidated Real Estate
Schedule of Equity Method Investments [Line Items]
Net property	1,363,889			834,367
Other assets	442,834			342,002
Other liabilities	323,442			290,071
Debt, net	833,716			585,068
Equity	$ 649,565			$ 301,230

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, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Revenue	$ 126,106			$ 145,331			$ 408,031	$ 433,378
Operating expenses	(99,601)			(118,675)			(327,678)	(354,651)
Interest expense	(16,310)			(20,400)			(56,510)	(61,273)
Depreciation and amortization	(43,533)			(55,627)			(145,314)	(158,738)
Net income	276,133	$ 4,020	$ 8,087	6,820	$ 6,252	$ 4,583	288,240	17,655
Equity in loss of Real Estate Ventures	(5,788)			(1,965)			(9,882)	(4,814)
Investment In Nonconsolidated Real Estate
Schedule of Equity Method Investments [Line Items]
Revenue	43,109			32,726			105,554	101,148
Operating expenses	(23,870)			(17,869)			(59,838)	(53,956)
Interest expense	(6,175)			(6,180)			(16,320)	(16,421)
Depreciation and amortization	(22,345)			(13,094)			(47,493)	(40,279)
Gain on early extinguishment of debt	0			4,371			0	4,371
Net income	(9,281)			(46)			(18,097)	(5,137)
Company's share of net loss	(5,812)			(1,945)			(9,892)	(4,765)
Basis adjustments and other	24			(20)			10	(49)
Equity in loss of Real Estate Ventures	$ (5,788)			$ (1,965)			$ (9,882)	$ (4,814)

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Fixed contractual payments	$ 95,751	$ 105,073	$ 302,146	$ 314,999
Variable lease payments	22,716	27,475	80,824	83,989
Total	$ 118,467	$ 132,548	$ 382,970	$ 398,988

Intangible Assets and Liabili_3

Intangible Assets and Liabilities - Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Intangible Assets [Line Items]
Intangible assets, total cost	$ 93,254	$ 177,581
Intangible assets, accumulated amortization	(42,539)	(92,730)
Intangible assets, net	50,715	84,851
Intangible liabilities, net		44,757
Acquired lease intangibles, accumulated amortization		(22,494)
Acquired lease intangibles, net	17,500	22,263
In-place lease value
Intangible Assets [Line Items]
Intangible assets, total cost	89,504	167,357
Intangible assets, accumulated amortization	(39,302)	(84,123)
Intangible assets, net	50,202	83,234
Tenant relationship value
Intangible Assets [Line Items]
Intangible assets, total cost	2,610	5,268
Intangible assets, accumulated amortization	(2,399)	(4,815)
Intangible assets, net	211	453
Above market leases acquired
Intangible Assets [Line Items]
Intangible assets, total cost	1,140	4,956
Intangible assets, accumulated amortization	(838)	(3,792)
Intangible assets, net	302	$ 1,164
Below market leases acquired
Intangible Assets [Line Items]
Intangible liabilities, net	29,189
Acquired lease intangibles, accumulated amortization	(11,689)
Acquired lease intangibles, net	$ 17,500

Intangible Assets and Liabili_4

Intangible Assets and Liabilities - Annual Amortization of Intangible Assets, Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
2020 (three months remaining)	$ 4,273
2021	14,789
2022	9,627
2023	7,564
2024	5,214
Thereafter	9,248
Intangible assets, net	50,715	$ 84,851
Liabilities
2020 (three months remaining)	1,011
2021	3,601
2022	2,065
2023	1,651
2024	1,425
Thereafter	7,747
Acquired lease intangibles, net	$ 17,500	$ 22,263

Debt Obligations - Consolidated

Debt Obligations - Consolidated Debt Obligations Outstanding (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Consolidated debt obligations
Plus: premiums/(discounts), net	$ 10,651
Less: deferred financing costs	(8,638)
Outstanding indebtedness	1,919,511	$ 2,144,418
Secured Debt
Consolidated debt obligations
Principal balance outstanding	88,888	315,437
Plus: premiums/(discounts), net	25	(1,383)
Less: deferred financing costs	0	(242)
Outstanding indebtedness	88,913	313,812
Secured Debt | Two Logan Square
Consolidated debt obligations
Principal balance outstanding	$ 79,781	81,103
Effective interest rate	3.98%
Secured Debt | Four Tower Bridge
Consolidated debt obligations
Principal balance outstanding	$ 9,107	9,291
Effective interest rate	4.50%
Secured Debt | One Commerce Square
Consolidated debt obligations
Principal balance outstanding	$ 0	116,571
Effective interest rate	3.64%
Secured Debt | Two Commerce Square
Consolidated debt obligations
Principal balance outstanding	$ 0	108,472
Effective interest rate	4.51%
Unsecured Debt
Consolidated debt obligations
Principal balance outstanding	$ 1,828,610	1,828,610
Plus: premiums/(discounts), net	10,626	12,090
Less: deferred financing costs	(8,638)	(10,094)
Outstanding indebtedness	1,830,598	1,830,606
Unsecured Debt | Seven-Year Term Loan - Swapped to fixed
Consolidated debt obligations
Principal balance outstanding	$ 250,000	250,000
Effective interest rate	2.87%
Unsecured Debt | $350.0M 3.95% Guaranteed Notes due 2023
Consolidated debt obligations
Principal balance outstanding	$ 350,000	350,000
Effective interest rate	3.87%
Unsecured Debt | $350.0M 4.10% Guaranteed Notes due 2024
Consolidated debt obligations
Principal balance outstanding	$ 350,000	350,000
Effective interest rate	3.78%
Unsecured Debt | $450.0M 3.95% Guaranteed Notes due 2027
Consolidated debt obligations
Principal balance outstanding	$ 450,000	450,000
Effective interest rate	4.03%
Unsecured Debt | $350.0M 4.55% Guaranteed Notes due 2029
Consolidated debt obligations
Principal balance outstanding	$ 350,000	350,000
Effective interest rate	4.30%
Unsecured Debt | Indenture IA (Preferred Trust I)
Consolidated debt obligations
Principal balance outstanding	$ 27,062	27,062
Unsecured Debt | Indenture IA (Preferred Trust I) | LIBOR
Consolidated debt obligations
Spread on variable rate	1.25%
Unsecured Debt | Indenture IB (Preferred Trust I) - Swapped to fixed
Consolidated debt obligations
Principal balance outstanding	$ 25,774	25,774
Effective interest rate	3.30%
Unsecured Debt | Indenture II (Preferred Trust II)
Consolidated debt obligations
Principal balance outstanding	$ 25,774	$ 25,774
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) - USD ($)	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 600,000,000
Weighted average interest rate	1.60%
LIBOR | Revolving Credit Facility
Debt Instrument [Line Items]
Spread on variable rate	1.10%
Unsecured Debt
Debt Instrument [Line Items]
Principal balance outstanding	$ 1,828,610,000	$ 1,828,610,000
Unsecured Debt | $600 million Unsecured Credit Facility
Debt Instrument [Line Items]
Principal balance outstanding	$ 0

Debt Obligations - Aggregate Sc

Debt Obligations - Aggregate Scheduled Principal Payments of Debt Obligation, Excluding Amortization of Discounts and Premiums (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
2020 (three months remaining)	$ 79,845
2021	9,043
2022	250,000
2023	350,000
2024	350,000
Thereafter	878,610
Total principal payments	1,917,498
Net unamortized premiums/(discounts)	10,651
Net deferred financing costs	(8,638)
Outstanding indebtedness	$ 1,919,511	$ 2,144,418

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, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage notes payable	$ 88,913	$ 313,812
Deferred financing costs, net	8,638
Unsecured notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred financing costs, net	8,638	10,094
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable	44,430	44,430
Carrying Amount | Unsecured notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unsecured notes payable	1,503,035	1,503,435
Deferred financing costs, net	7,600	8,700
Carrying Amount | Variable rate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Variable rate debt	327,563	327,171
Deferred financing costs, net	1,000	1,400
Carrying Amount | Mortgage notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage notes payable	88,913	313,812
Deferred financing costs, net	0	200
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Note receivable, fair value	47,415	43,322
Fair Value | Unsecured notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	1,566,650	1,591,830
Fair Value | Variable rate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	308,519	309,947
Fair Value | Mortgage notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	$ 89,034	$ 317,031

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Textual (Details) - Brandywine 1919 Ventures $ in Millions	Jun. 26, 2018USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage loan	$ 44.4
Equity method investment, ownership percentage	50.00%
Other Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage loan	$ 44.4

Derivative Financial Instrume_3

Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative, notional amount	$ 275,774	$ 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	$ (7,597)	(562)
3.300% Interest Rate Swap Maturing January 30, 2021 | Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Derivative liability, notional amount	$ 25,774	25,774
Derivative, fixed interest rate	3.30%
Derivative liability, fair value, gross liability	$ (234)	$ (94)

Limited Partners' Non-Control_2

Limited Partners' Non-Controlling Interests in the Parent Company (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Aggregate amount related to non-controlling interests classified within equity	$ 10.5	$ 9.3
Settlement value of non controlling interest in operating partnership	$ 10.2	$ 15.5

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, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator
Net income	$ 276,133	$ 4,020	$ 8,087	$ 6,820	$ 6,252	$ 4,583	$ 288,240	$ 17,655
Net income attributable to noncontrolling interests, Basic	(1,612)			(48)			(1,701)	(155)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(93)			(93)			(317)	(305)
Net income attributable to noncontrolling interests, Diluted	(1,612)			(48)			(1,701)	(155)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(93)			(93)			(317)	(305)
Net income attributable to Common Shareholders of Brandywine Realty Trust	274,428			6,679			286,222	17,195
Net income attributable to common shareholders, Diluted	$ 274,428			$ 6,679			$ 286,222	$ 17,195
Denominator
Basic weighted average shares outstanding (in shares)	170,573,028			176,195,244			172,380,410	176,066,507
Contingent securities/Share based compensation (in shares)	453,464			555,356			355,026	551,219
Diluted weighted average shares outstanding (in shares)	171,026,492			176,750,600			172,735,436	176,617,726
Earnings per Common Share:
Net income attributable to common shareholders, Basic (USD per share)	$ 1.61			$ 0.04			$ 1.66	$ 0.10
Net income attributable to common shareholders, Diluted (USD per share)	$ 1.60			$ 0.04			$ 1.66	$ 0.10

Beneficiaries Equity of the P_4

Beneficiaries Equity of the Parent Company - Textual (Details) - USD ($)	Sep. 15, 2020	Jun. 30, 2020	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Jan. 03, 2019
Class of Stock [Line Items]
Dividends, common stock	$ 32,700,000
Shares repurchased and retired (in shares)					6,248,483	1,337,169
Share price (in dollars per share)					$ 9.60	$ 12.92
Value of stock repurchased and retired		$ 6,141,000	$ 53,858,000	$ 17,281,000	$ 60,000,000	$ 17,300,000
Maximum
Class of Stock [Line Items]
Share repurchase, authorized amount							$ 150,000,000
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)					981,634	981,626

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, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator
Net income	$ 276,133	$ 4,020	$ 8,087	$ 6,820	$ 6,252	$ 4,583	$ 288,240	$ 17,655
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(93)			(93)			(317)	(305)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (93)			$ (93)			$ (317)	$ (305)
Denominator
Basic weighted average shares outstanding (in shares)	170,573,028			176,195,244			172,380,410	176,066,507
Contingent securities/Share based compensation (in shares)	453,464			555,356			355,026	551,219
Diluted weighted average shares outstanding (in shares)	171,026,492			176,750,600			172,735,436	176,617,726
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 1.61			$ 0.04			$ 1.66	$ 0.10
Net income attributable to common shareholders, Diluted (USD per share)	$ 1.60			$ 0.04			$ 1.66	$ 0.10
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Net income	$ 276,133	$ 4,020	$ 8,087	$ 6,820	$ 6,252	$ 4,583	$ 288,240	$ 17,655
Net income attributable to noncontrolling interests	2			(11)			(20)	(58)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(93)			(93)			(317)	(305)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(93)			(93)			(317)	(305)
Net income attributable to common unitholders, Basic	276,042			6,716			287,903	17,292
Net income attributable to common unitholders, Diluted	$ 276,042			$ 6,716			$ 287,903	$ 17,292
Denominator
Basic weighted average shares outstanding (in shares)	171,554,662			177,176,870			173,362,044	177,048,621
Contingent securities/Share based compensation (in shares)	453,464			555,356			355,026	551,219
Diluted weighted average shares outstanding (in shares)	172,008,126			177,732,226			173,717,070	177,599,840
Earnings per Common Partnership Unit:
Net income attributable to common shareholders, Basic (USD per share)	$ 1.61			$ 0.04			$ 1.66	$ 0.10
Net income attributable to common shareholders, Diluted (USD per share)	$ 1.60			$ 0.04			$ 1.66	$ 0.10

Partners' Equity Of The Paren_4

Partners' Equity Of The Parent Company - Textual (Details) $ / shares in Units, $ in Thousands	Sep. 15, 2020USD ($)$ / shares	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2020USD ($)$ / sharesshares	Sep. 30, 2019USD ($)$ / sharesshares
Earnings Per Common Partnership Unit [Line Items]
Dividends, common stock | $	$ 32,700
Shares repurchased and retired (in shares) | shares					6,248,483	1,337,169
Share price (in dollars per share) | $ / shares					$ 9.60	$ 12.92
Value of stock repurchased and retired | $		$ 6,141	$ 53,858	$ 17,281	$ 60,000	$ 17,300
Dividend declared
Earnings Per Common Partnership Unit [Line Items]
Dividends payable (in dollars per share) | $ / shares	$ 0.19
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings Per Common Partnership Unit [Line Items]
Dividends, common stock | $	$ 32,700
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 share) | $ / shares	$ 0.19

Segment Information (Textual) (

Segment Information (Textual) (Details)	9 Months Ended
	Sep. 30, 2020segment
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, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Operating properties	$ 3,715,765	$ 4,006,459
Operating Properties	3,715,765	4,006,459
Right of use asset - operating leases, net	21,145	21,656
Construction-in-progress	186,853	180,718
Land held for development	115,474	96,124
Prepaid leasehold interests in land held for development, net	39,287	39,592
Philadelphia CBD
Segment Reporting Information [Line Items]
Operating properties	1,414,041	1,726,299
Pennsylvania Suburbs
Segment Reporting Information [Line Items]
Operating properties	1,000,214	1,003,890
Austin, Texas
Segment Reporting Information [Line Items]
Operating properties	726,295	721,255
Metropolitan Washington, D.C.
Segment Reporting Information [Line Items]
Operating properties	488,139	468,035
Other
Segment Reporting Information [Line Items]
Operating properties	$ 87,076	$ 86,980

Segment Information - Real Es_2

Segment Information - Real Estate Investments, at Cost of Company's Reportable Segments (Additional Information) (Details) - a	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
3001-3003 and 3025 JFK Boulevard
Segment Reporting Information [Line Items]
Lease agreement term	99 years	99 years
Held-for-sale
Segment Reporting Information [Line Items]
Area of land (in acres)	35.2	35.2

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Total revenue	$ 126,106	$ 145,331	$ 408,031	$ 433,378
Operating expenses	(48,999)	(56,074)	(158,391)	(170,696)
Net operating income (loss)	77,107	89,257	249,640	262,682
Operating Segments | Philadelphia CBD
Segment Reporting Information [Line Items]
Total revenue	52,640	66,105	181,203	196,859
Operating expenses	(18,522)	(24,773)	(65,615)	(75,311)
Net operating income (loss)	34,118	41,332	115,588	121,548
Operating Segments | Pennsylvania Suburbs
Segment Reporting Information [Line Items]
Total revenue	34,649	34,818	106,569	104,744
Operating expenses	(11,141)	(11,667)	(34,980)	(36,466)
Net operating income (loss)	23,508	23,151	71,589	68,278
Operating Segments | Austin, Texas
Segment Reporting Information [Line Items]
Total revenue	25,328	26,280	76,921	77,234
Operating expenses	(9,944)	(9,302)	(30,032)	(28,182)
Net operating income (loss)	15,384	16,978	46,889	49,052
Operating Segments | Metropolitan Washington, D.C.
Segment Reporting Information [Line Items]
Total revenue	9,675	13,179	30,520	40,372
Operating expenses	(5,236)	(5,999)	(15,678)	(18,542)
Net operating income (loss)	4,439	7,180	14,842	21,830
Operating Segments | Other
Segment Reporting Information [Line Items]
Total revenue	3,188	3,706	10,221	10,352
Operating expenses	(2,374)	(2,691)	(7,434)	(7,226)
Net operating income (loss)	814	1,015	2,787	3,126
Corporate
Segment Reporting Information [Line Items]
Total revenue	626	1,243	2,597	3,817
Operating expenses	(1,782)	(1,642)	(4,652)	(4,969)
Net operating income (loss)	$ (1,156)	$ (399)	$ (2,055)	$ (1,152)

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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Investment in real estate ventures	$ 367,771		$ 367,771		$ 120,294
Equity in loss of real estate ventures	(5,788)	$ (1,965)	(9,882)	$ (4,814)
Philadelphia CBD
Segment Reporting Information [Line Items]
Investment in real estate ventures	277,161		277,161		17,524
Equity in loss of real estate ventures	(2,737)	55	(2,575)	217
Metropolitan Washington, D.C.
Segment Reporting Information [Line Items]
Investment in real estate ventures	100,325		100,325		102,840
Equity in loss of real estate ventures	(1,367)	(528)	(2,463)	(963)
MAP Venture
Segment Reporting Information [Line Items]
Investment in real estate ventures	(9,715)		(9,715)		(70)
Equity in loss of real estate ventures	(1,684)	(1,602)	(4,844)	(4,414)
Other
Segment Reporting Information [Line Items]
Investment in real estate ventures	0		0		$ 0
Equity in loss of real estate ventures	$ 0	$ 110	$ 0	$ 346

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, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting [Abstract]
Net income	$ 276,133	$ 4,020	$ 8,087	$ 6,820	$ 6,252	$ 4,583	$ 288,240	$ 17,655
Plus:
Interest expense	16,310			20,400			56,510	61,273
Interest expense - amortization of deferred financing costs	715			694			2,195	2,026
Depreciation and amortization	43,533			55,627			145,314	158,738
General and administrative expenses	7,069			6,974			23,973	25,217
Equity in loss of Real Estate Ventures	5,788			1,965			9,882	4,814
Less:
Interest income	467			558			1,487	1,636
Income tax (provision) benefit	(2)			0			224	(46)
Net gain on disposition of real estate	271,901			356			274,487	356
Net gain on sale of undepreciated real estate	0			250			201	1,501
Net gain on real estate venture transactions	75			2,059			75	3,594
Consolidated net operating income	$ 77,107			$ 89,257			$ 249,640	$ 262,682

Commitments and Contingencies (

Commitments and Contingencies (Details) ft² in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)ft²	Dec. 31, 2019USD ($)
Property Subject to or Available for Operating Lease [Line Items]
Debt, net	$ 1,919,511,000	$ 2,144,418,000
4040 Wilson Venture
Property Subject to or Available for Operating Lease [Line Items]
Debt, net	150,000,000
Guarantees, maximum exposure amount	41,300,000
Unconsolidated Real Estate Ventures
Property Subject to or Available for Operating Lease [Line Items]
Real estate ventures aggregate indebtedness	$ 842,200,000
Radnor PA Property
Property Subject to or Available for Operating Lease [Line Items]
Rentable area (in square feet) | ft²	170
Payments to acquire buildings	$ 20,300,000
Payments for deposits on real estate acquisitions	1,000,000
One and Two Commerce Square | Preferred Equity Investment
Property Subject to or Available for Operating Lease [Line Items]
Other commitments	20,000,000
Drexel Square
Property Subject to or Available for Operating Lease [Line Items]
Other commitments	7,700,000
Estimated potential additional contribution obligation	2,600,000
Mortgage Lenders
Property Subject to or Available for Operating Lease [Line Items]
Associated letter of credit	$ 0

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	Oct. 21, 2020USD ($)
Secured Debt | Two Logan Square | Subsequent Event
Subsequent Event [Line Items]
Acquisition of mortgage loan	$ 79.8