Brandywine Realty Trust (BDN) 10-K 22 Feb 24 2023 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2023	Feb. 20, 2024	Jun. 30, 2023
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity Registrant Name	Brandywine Realty Trust
Entity Incorporation, State or Country Code	MD
Entity File Number	001-9106
Entity Tax Identification Number	23-2413352
Entity Address, Address Line One	2929 Arch Street
Entity Address, Address Line Two	Suite 1800
Entity Address, City or Town	Philadelphia
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19104
City Area Code	610
Local Phone Number	325-5600
Title of 12(b) Security	Common Shares of Beneficial Interest
Trading Symbol	BDN
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 774,783,512
Entity Common Stock, Shares Outstanding		172,240,888
Documents Incorporated by Reference	Portions of the proxy statement for the 2023 Annual Meeting of Shareholders of Brandywine Realty Trust are incorporated by reference into Part III of this Form 10-K.
Entity Central Index Key	0000790816
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Central Index Key	0001060386

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Auditor Information [Abstract]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Philadelphia, Pennsylvania
Auditor Firm ID	238

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Real estate investments:
Operating properties	$ 3,542,232	$ 3,617,240
Accumulated depreciation	(1,131,792)	(1,063,060)
Right of use asset - operating leases, net	19,031	19,664
Operating real estate investments, net	2,429,471	2,573,844
Construction-in-progress	135,529	218,869
Land held for development	82,510	76,499
Prepaid leasehold interests in land held for development, net	27,762	35,576
Total real estate investments, net	2,675,272	2,904,788
Cash and cash equivalents	58,319	17,551
Restricted cash and escrows	9,215	0
Accounts receivable	11,977	11,003
Accrued rent receivable, net of allowance of $2,672 and $3,947 as of December 31, 2023 and December 31, 2022, respectively	186,708	179,771
Investment in unconsolidated real estate ventures	601,227	567,635
Deferred costs, net	95,984	96,639
Intangible assets, net	7,694	18,451
Other assets	86,051	78,667
Total assets	3,732,447	3,874,505
LIABILITIES AND BENEFICIARIES' EQUITY
Secured term loan, net	255,671	0
Unsecured credit facility	0	88,500
Unsecured term loan, net	318,499	248,168
Unsecured senior notes, net	1,564,662	1,628,370
Accounts payable and accrued expenses	123,825	132,440
Distributions payable	26,017	32,792
Deferred income, gains and rent	24,248	25,082
Intangible liabilities, net	8,270	10,322
Lease liability - operating leases	23,369	23,166
Other liabilities	63,729	52,331
Total liabilities	2,408,290	2,241,171
Commitments and contingencies (See Note 20)
Brandywine Realty Trust's Equity:
Common Shares of Brandywine Realty Trust's beneficial interest, $0.01 par value; shares authorized 400,000,000; 172,097,661 and 171,569,807 issued and outstanding as of December 31, 2023 and December 31, 2022, respectively	1,719	1,716
Additional paid-in-capital	3,163,949	3,153,229
Deferred compensation payable in common shares	19,965	19,601
Common shares in grantor trust, 1,194,127 and 1,179,643 issued and outstanding as of December 31, 2023 and December 31, 2022, respectively	(19,965)	(19,601)
Cumulative earnings	979,406	1,176,195
Accumulated other comprehensive income (loss)	(668)	3,897
Cumulative distributions	(2,827,022)	(2,709,405)
Total Brandywine Realty Trust's equity	1,317,384	1,625,632
Noncontrolling interests	6,773	7,702
Total beneficiaries' equity	1,324,157	1,633,334
Total liabilities and beneficiaries' equity	$ 3,732,447	$ 3,874,505

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Accrued rent receivable, allowance	$ 2,672	$ 3,947
Common stock, par or stated value per share (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common shares in grantor trust, issued and outstanding (in shares)	1,194,127	1,179,643

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue
Total revenue	$ 514,651	$ 506,100	$ 486,819
Operating expenses
Property operating expenses	129,885	130,209	121,890
Real estate taxes	49,974	53,645	53,621
Third party management expenses	10,088	10,547	12,800
Depreciation and amortization	188,797	177,984	178,105
General and administrative expenses	34,862	35,006	30,153
Provision for impairment	131,573	4,663	0
Total operating expenses	545,179	412,054	396,569
Gain on sale of real estate
Net gain on disposition of real estate	7,736	17,677	142
Net gain on sale of undepreciated real estate	1,211	8,007	2,903
Total gain on sale of real estate	8,947	25,684	3,045
Operating income (loss)	(21,581)	119,730	93,295
Other income (expense):
Interest and investment income	1,671	1,905	8,295
Interest expense	(95,456)	(68,764)	(62,617)
Interest expense - amortization of deferred financing costs	(4,369)	(3,091)	(2,836)
Investment (loss) income	(77,915)	(22,016)	(26,697)
Net gain on real estate venture transactions	181	26,718	2,973
Gain (loss) on early extinguishment of debt	138	(435)	0
Net income (loss) before income taxes	(197,331)	54,047	12,413
Income tax provision	(72)	(55)	(47)
Net income (loss)	(197,403)	53,992	12,366
Net (income) loss attributable to noncontrolling interests	614	(168)	(77)
Net income (loss) attributable to Brandywine Realty Trust	(196,789)	53,824	12,289
Nonforfeitable dividends allocated to unvested restricted shareholders	(567)	(456)	(421)
Net income (loss) attributable to common shareholders, Basic	$ (197,356)	$ 53,368	$ 11,868
Basic income (loss) per Common Share (in dollars per shares)	$ (1.15)	$ 0.31	$ 0.07
Diluted income (loss) per Common Share (in dollars per share)	$ (1.15)	$ 0.31	$ 0.07
Basic weighted average shares outstanding (in shares)	171,959,210	171,491,369	170,878,185
Diluted weighted average shares outstanding (in shares)	171,959,210	172,325,646	172,273,240
Rents
Revenue
Total revenue	$ 479,849	$ 470,851	$ 451,519
Third party management fees, labor reimbursement and leasing
Revenue
Total revenue	24,417	24,132	26,444
Other
Revenue
Total revenue	$ 10,385	$ 11,117	$ 8,856

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ (197,403)	$ 53,992	$ 12,366
Comprehensive income (loss):
Unrealized gain (loss) on derivative financial instruments		(4,579)	5,371	4,817
Amortization of interest rate contracts	[1]	0	564	752
Total comprehensive income (loss)		(4,579)	5,935	5,569
Comprehensive income (loss)		(201,982)	59,927	17,935
Comprehensive (income) loss attributable to noncontrolling interest		628	(186)	(105)
Comprehensive income (loss) attributable to Brandywine Realty Trust		$ (201,354)	$ 59,741	$ 17,830
[1] Amounts reclassified from comprehensive income to interest expense within the Consolidated Statements of Operations.

CONSOLIDATED STATEMENTS OF BENE

CONSOLIDATED STATEMENTS OF BENEFICIARIES’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Rabbi Trust/Deferred Compensation Shares	Additional Paid-in Capital	Common Shares in Grantor Trust	Cumulative Earnings	Accumulated Other Comprehensive Income (Loss)	Cumulative Distributions	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2020		170,572,964	1,160,494
Beginning balance at Dec. 31, 2020	$ 1,804,648	$ 1,707	$ 17,516	$ 3,138,152	$ (17,516)	$ 1,110,083	$ (7,561)	$ (2,448,238)	$ 10,505
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	12,366					12,289			77
Other comprehensive income	5,569						5,541		28
Issuance of Common Shares of Beneficial Interest (in shares)		226,695
Issuance of Common Shares of Beneficial Interest	3,052	$ 3		3,049
Issuance of partnership interest in consolidated real estate venture	2,765								2,765
Redemption of LP Units	(2,334)								(2,334)
Share-based compensation activity (in shares)		344,656	70,645
Share-based compensation activity	6,354	$ 2		6,352
Share Issuance from/(to) Deferred Compensation Plan (in shares)		(18,058)	(61,436)
Share Issuance from/(to) Deferred Compensation Plan	(198)		$ 975	(198)	(975)
Reallocation of Noncontrolling Interest	0			(569)					569
Distributions declared	(131,003)							(130,345)	(658)
Ending balance (in shares) at Dec. 31, 2021		171,126,257	1,169,703
Ending balance at Dec. 31, 2021	1,701,219	$ 1,712	$ 18,491	3,146,786	(18,491)	1,122,372	(2,020)	(2,578,583)	10,952
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	53,992					53,824			168
Other comprehensive income	5,935						5,917		18
Redemption of LP Units	(4,006)								(4,006)
Share-based compensation activity (in shares)		469,529	85,384
Share-based compensation activity	7,718	$ 4		7,714
Share Issuance from/(to) Deferred Compensation Plan (in shares)		(25,979)	(75,444)
Share Issuance from/(to) Deferred Compensation Plan	(312)		$ 1,110	(312)	(1,110)
Reallocation of Noncontrolling Interest	(1)			(959)		(1)			959
Distributions declared	(131,211)							(130,822)	(389)
Ending balance (in shares) at Dec. 31, 2022		171,569,807	1,179,643
Ending balance at Dec. 31, 2022	1,633,334	$ 1,716	$ 19,601	3,153,229	(19,601)	1,176,195	3,897	(2,709,405)	7,702
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(197,403)					(196,789)			(614)
Other comprehensive income	(4,579)						(4,565)		(14)
Share-based compensation activity (in shares)		545,544	76,505
Share-based compensation activity	10,880	$ 3		10,877
Share Issuance from/(to) Deferred Compensation Plan (in shares)		(17,690)	(62,021)
Share Issuance from/(to) Deferred Compensation Plan	(108)		$ 364	(108)	(364)
Reallocation of Noncontrolling Interest	0			(49)					49
Distributions declared	(117,967)							(117,617)	(350)
Ending balance (in shares) at Dec. 31, 2023		172,097,661	1,194,127
Ending balance at Dec. 31, 2023	$ 1,324,157	$ 1,719	$ 19,965	$ 3,163,949	$ (19,965)	$ 979,406	$ (668)	$ (2,827,022)	$ 6,773

CONSOLIDATED STATEMENTS OF BE_2

CONSOLIDATED STATEMENTS OF BENEFICIARIES’ EQUITY (Parenthetical) - $ / shares		12 Months Ended
	Dec. 05, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Stockholders' Equity [Abstract]
Distributions declared (in dollars per share)	$ 0.15	$ 0.68	$ 0.76	$ 0.76

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income (loss)	$ (197,403)	$ 53,992	$ 12,366
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	188,797	177,984	178,105
Amortization of deferred financing costs	4,369	3,091	2,836
Amortization of debt discount/(premium), net	(1,056)	(5,254)	(1,951)
Amortization of stock compensation costs	9,847	8,939	7,130
Straight-line rent income	(9,270)	(13,631)	(13,485)
Amortization of acquired above (below) market leases, net	(1,256)	(2,581)	(5,377)
Straight-line ground rent expense	799	814	918
Net gain on real estate venture transactions	(181)	(26,718)	(2,973)
Total gain on sale of real estate	(8,947)	(25,684)	(3,045)
Gain (loss) on early extinguishment of debt	(138)	435	0
Provision for impairment	131,573	4,663	0
Loss from unconsolidated real estate ventures, including income distributions	77,915	23,522	26,697
Income tax provision	72	55	47
Changes in assets and liabilities:
Accounts receivable	241	1,328	2,506
Other assets	(2,831)	(1,120)	(19,325)
Accounts payable and accrued expenses	(12,928)	5,405	2,974
Deferred income, gains and rent	(86)	1,567	2,986
Other liabilities	(2,244)	2,500	465
Net cash provided by operating activities	177,273	209,307	190,874
Cash flows from investing activities:
Acquisition of properties	(7,747)	(3,446)	0
Proceeds from the sale of properties	76,804	64,210	10,303
Proceeds from insurance	0	0	1,250
Proceeds from note receivable	0	44,300	50,000
Capital expenditures for tenant improvements	(48,939)	(86,774)	(56,830)
Capital expenditures for redevelopments	(59,984)	(87,223)	(48,022)
Capital expenditures for developments	(47,537)	(89,017)	(30,269)
Advances for the purchase of tenant assets, net of repayments	(998)	(447)	270
Investment in unconsolidated real estate ventures	(85,922)	(47,428)	(31,643)
Deposits for real estate	3,500	(4,900)	(2,550)
Capital distributions from unconsolidated real estate ventures	3,790	46,898	27,028
Leasing costs paid	(7,879)	(26,762)	(19,852)
Net cash used in investing activities	(174,912)	(190,589)	(100,315)
Cash flows from financing activities:
Proceeds from credit facility borrowings	215,000	478,000	154,000
Repayments of credit facility borrowings	(303,500)	(412,500)	(131,000)
Proceeds from unsecured notes	0	350,000	0
Repayments of unsecured notes	(64,164)	(296,134)	0
Proceeds from unsecured term loan	70,000	0	0
Proceeds from secured term loan	245,000	0	0
Proceeds from construction loan	13,824	0	0
Debt financing costs paid	(4,371)	(9,875)	0
Exercise of stock options, net	0	0	(63)
Shares used for employee taxes upon vesting of share awards	(371)	(2,941)	(1,762)
Partner contributions to consolidated real estate venture	0	0	2,765
Redemption of limited partnership units	(5)	(4,006)	(2,334)
Distributions paid to shareholders	(124,255)	(130,724)	(130,255)
Distributions to noncontrolling interest	(372)	(451)	(687)
Net cash provided by (used in) financing activities	46,786	(28,631)	(109,336)
Increase/(Decrease) in cash and cash equivalents and restricted cash	49,147	(9,913)	(18,777)
Cash and cash equivalents and restricted cash at beginning of year	18,387	28,300	47,077
Cash and cash equivalents and restricted cash at end of period	67,534	18,387	28,300
Reconciliation of cash and cash equivalents and restricted cash:
Cash and cash equivalents, beginning of period	17,551	27,463	46,344
Restricted cash, beginning of period	836	837	733
Cash and cash equivalents, end of period	58,319	17,551	27,463
Restricted cash, end of period	9,215	836	837
Cash and cash equivalents and restricted cash	67,534	18,387	28,300
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the years ended December 31, 2023, 2022 and 2021 of $16,410, $10,517 and $8,689 respectively	107,838	85,761	72,391
Cash paid for income taxes	550	902	785
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	26,017	32,792	32,765
Extinguishment of debt costs accrued in financing activities	0	393	0
Change in investment in real estate ventures as a result of deconsolidation	8,595	107,057	32,761
Change in operating real estate from deconsolidation of operating properties	(7,814)	(92,009)	(30,073)
Change in other assets as a result of deconsolidation of operating properties	0	(15,048)	(2,688)
Change in capital expenditures financed through accounts payable at period end	(3,282)	(6,135)	22,744
Change in capital expenditures financed through retention payable at period end	$ 2,715	$ (7,165)	$ (613)

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Supplemental disclosure:
Capitalized interest	$ 16,410	$ 10,517	$ 8,689

CONSOLIDATED BALANCE SHEETS - B

CONSOLIDATED BALANCE SHEETS - BRANDYWINE OPERATING PARTNERSHIP, L.P. - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Real estate investments:
Operating properties	$ 3,542,232	$ 3,617,240
Accumulated depreciation	(1,131,792)	(1,063,060)
Right of use asset - operating leases, net	19,031	19,664
Operating real estate investments, net	2,429,471	2,573,844
Construction-in-progress	135,529	218,869
Land held for development	82,510	76,499
Prepaid leasehold interests in land held for development, net	27,762	35,576
Total real estate investments, net	2,675,272	2,904,788
Cash and cash equivalents	58,319	17,551
Restricted cash and escrows	9,215	0
Accounts receivable	11,977	11,003
Accrued rent receivable, net of allowance of $2,672 and $3,947 as of December 31, 2023 and December 31, 2022, respectively	186,708	179,771
Investment in unconsolidated real estate ventures	601,227	567,635
Deferred costs, net	95,984	96,639
Intangible assets, net	7,694	18,451
Other assets	86,051	78,667
Total assets	3,732,447	3,874,505
LIABILITIES AND PARTNERS' EQUITY
Secured term loan, net	255,671	0
Unsecured credit facility	0	88,500
Unsecured term loan, net	318,499	248,168
Unsecured senior notes, net	1,564,662	1,628,370
Accounts payable and accrued expenses	123,825	132,440
Distributions payable	26,017	32,792
Deferred income, gains and rent	24,248	25,082
Intangible liabilities, net	8,270	10,322
Lease liability - operating leases	23,369	23,166
Other liabilities	63,729	52,331
Total liabilities	2,408,290	2,241,171
Commitments and contingencies (See Note 20)
Brandywine Operating Partnership, L.P.'s equity:
Accumulated other comprehensive income (loss)	(668)	3,897
Total liabilities and beneficiaries' equity	3,732,447	3,874,505
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Operating properties	3,542,232	3,617,240
Accumulated depreciation	(1,131,792)	(1,063,060)
Right of use asset - operating leases, net	19,031	19,664
Operating real estate investments, net	2,429,471	2,573,844
Construction-in-progress	135,529	218,869
Land held for development	82,510	76,499
Prepaid leasehold interests in land held for development, net	27,762	35,576
Total real estate investments, net	2,675,272	2,904,788
Cash and cash equivalents	58,319	17,551
Accounts receivable	11,977	11,003
Accrued rent receivable, net of allowance of $2,672 and $3,947 as of December 31, 2023 and December 31, 2022, respectively	186,708	179,771
Investment in unconsolidated real estate ventures	601,227	567,635
Deferred costs, net	95,984	96,639
Intangible assets, net	7,694	18,451
Other assets	86,051	78,667
Total assets	3,732,447	3,874,505
LIABILITIES AND PARTNERS' EQUITY
Secured term loan, net	255,671	0
Unsecured credit facility	0	88,500
Unsecured term loan, net	318,499	248,168
Unsecured senior notes, net	1,564,662	1,628,370
Accounts payable and accrued expenses	123,825	132,440
Distributions payable	26,017	32,792
Deferred income, gains and rent	24,248	25,082
Intangible liabilities, net	8,270	10,322
Lease liability - operating leases	23,369	23,166
Other liabilities	63,729	52,331
Total liabilities	2,408,290	2,241,171
Commitments and contingencies (See Note 20)
Redeemable limited partnership units at redemption value; 515,595 and 516,467 issued and outstanding as of December 31, 2023 and December 31, 2022, respectively	2,785	3,195
Brandywine Operating Partnership, L.P.'s equity:
General Partnership Capital; 172,097,661 and 171,569,807 units issued and outstanding as of December 31, 2023 and December 31, 2022, respectively	1,319,572	1,623,738
Accumulated other comprehensive income (loss)	(1,010)	3,569
Total Brandywine Operating Partnership, L.P.'s equity	1,318,562	1,627,307
Noncontrolling interest - consolidated real estate ventures	2,810	2,832
Total partners' equity	1,321,372	1,630,139
Total liabilities and beneficiaries' equity	$ 3,732,447	$ 3,874,505

CONSOLIDATED BALANCE SHEETS -_2

CONSOLIDATED BALANCE SHEETS - BRANDYWINE OPERATING PARTNERSHIP, L.P. (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accrued rent receivable, allowance	$ 2,672	$ 3,947
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Accrued rent receivable, allowance	$ 2,672	$ 3,947
Common stock, shares, issued (in shares)	172,097,661	171,569,807
Common stock, shares, outstanding (in shares)	172,097,661	171,569,807
BRANDYWINE OPERATING PARTNERSHIP, L.P. | Class A Units
Redeemable limited partnership units issued (in units)	515,595	516,467
Redeemable limited partnership units outstanding (in units)	515,595	516,467

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS - BRANDYWINE OPERATING PARTNERSHIP, L.P. - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue
Total revenue	$ 514,651	$ 506,100	$ 486,819
Operating expenses
Property operating expenses	129,885	130,209	121,890
Real estate taxes	49,974	53,645	53,621
Third party management expenses	10,088	10,547	12,800
Depreciation and amortization	188,797	177,984	178,105
General and administrative expenses	34,862	35,006	30,153
Provision for impairment	131,573	4,663	0
Total operating expenses	545,179	412,054	396,569
Gain on sale of real estate
Net gain on disposition of real estate	7,736	17,677	142
Net gain on sale of undepreciated real estate	1,211	8,007	2,903
Total gain on sale of real estate	8,947	25,684	3,045
Operating income (loss)	(21,581)	119,730	93,295
Other income (expense):
Interest and investment income	1,671	1,905	8,295
Interest expense	(95,456)	(68,764)	(62,617)
Interest expense - amortization of deferred financing costs	(4,369)	(3,091)	(2,836)
Investment (loss) income	(77,915)	(22,016)	(26,697)
Net gain on real estate venture transactions	181	26,718	2,973
Gain (loss) on early extinguishment of debt	138	(435)	0
Net income (loss) before income taxes	(197,331)	54,047	12,413
Income tax provision	(72)	(55)	(47)
Net income (loss)	(197,403)	53,992	12,366
Nonforfeitable dividends allocated to unvested restricted shareholders	(567)	(456)	(421)
Net income (loss) attributable to common shareholders, Basic	$ (197,356)	$ 53,368	$ 11,868
Basic income (loss) per Common Share (in dollars per shares)	$ (1.15)	$ 0.31	$ 0.07
Diluted income (loss) per Common Share (in dollars per share)	$ (1.15)	$ 0.31	$ 0.07
Basic weighted average shares outstanding (in shares)	171,959,210	171,491,369	170,878,185
Diluted weighted average shares outstanding (in shares)	171,959,210	172,325,646	172,273,240
Rents
Revenue
Total revenue	$ 479,849	$ 470,851	$ 451,519
Third party management fees, labor reimbursement and leasing
Revenue
Total revenue	24,417	24,132	26,444
Other
Revenue
Total revenue	10,385	11,117	8,856
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Total revenue	514,651	506,100	486,819
Operating expenses
Property operating expenses	129,885	130,209	121,890
Real estate taxes	49,974	53,645	53,621
Third party management expenses	10,088	10,547	12,800
Depreciation and amortization	188,797	177,984	178,105
General and administrative expenses	34,862	35,006	30,153
Provision for impairment	131,573	4,663	0
Total operating expenses	545,179	412,054	396,569
Gain on sale of real estate
Net gain on disposition of real estate	7,736	17,677	142
Net gain on sale of undepreciated real estate	1,211	8,007	2,903
Total gain on sale of real estate	8,947	25,684	3,045
Operating income (loss)	(21,581)	119,730	93,295
Other income (expense):
Interest and investment income	1,671	1,905	8,295
Interest expense	(95,456)	(68,764)	(62,617)
Interest expense - amortization of deferred financing costs	(4,369)	(3,091)	(2,836)
Investment (loss) income	(77,915)	(22,016)	(26,697)
Net gain on real estate venture transactions	181	26,718	2,973
Gain (loss) on early extinguishment of debt	138	(435)	0
Net income (loss) before income taxes	(197,331)	54,047	12,413
Income tax provision	(72)	(55)	(47)
Net income (loss)	(197,403)	53,992	12,366
Net loss attributable to noncontrolling interests - consolidated real estate ventures	22	2	3
Net income (loss) attributable to Brandywine Operating Partnership	(197,381)	53,994	12,369
Nonforfeitable dividends allocated to unvested restricted shareholders	(567)	(456)	(421)
Net income (loss) attributable to common shareholders, Basic	$ (197,948)	$ 53,538	$ 11,948
Basic income (loss) per Common Share (in dollars per shares)	$ (1.15)	$ 0.31	$ 0.07
Diluted income (loss) per Common Share (in dollars per share)	$ (1.15)	$ 0.31	$ 0.07
Basic weighted average shares outstanding (in shares)	172,475,645	172,036,481	171,770,843
Diluted weighted average shares outstanding (in shares)	172,475,645	172,870,758	173,165,898
BRANDYWINE OPERATING PARTNERSHIP, L.P. | Rents
Revenue
Total revenue	$ 479,849	$ 470,851	$ 451,519
BRANDYWINE OPERATING PARTNERSHIP, L.P. | Third party management fees, labor reimbursement and leasing
Revenue
Total revenue	24,417	24,132	26,444
BRANDYWINE OPERATING PARTNERSHIP, L.P. | Other
Revenue
Total revenue	$ 10,385	$ 11,117	$ 8,856

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - BRANDYWINE OPERATING PARTNERSHIP, L.P. - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net income (loss)		$ (197,403)	$ 53,992	$ 12,366
Comprehensive income (loss):
Unrealized gain (loss) on derivative financial instruments		(4,579)	5,371	4,817
Amortization of interest rate contracts	[1]	0	564	752
Total comprehensive income (loss)		(4,579)	5,935	5,569
Comprehensive income (loss)		(201,982)	59,927	17,935
Comprehensive loss attributable to noncontrolling interest - consolidated real estate ventures		628	(186)	(105)
Comprehensive income (loss) attributable to Brandywine Realty Trust		(201,354)	59,741	17,830
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Net income (loss)		(197,403)	53,992	12,366
Comprehensive income (loss):
Unrealized gain (loss) on derivative financial instruments		(4,579)	5,371	4,817
Amortization of interest rate contracts	[1]	0	564	752
Total comprehensive income (loss)		(4,579)	5,935	5,569
Comprehensive income (loss)		(201,982)	59,927	17,935
Comprehensive loss attributable to noncontrolling interest - consolidated real estate ventures		22	2	3
Comprehensive income (loss) attributable to Brandywine Realty Trust		$ (201,960)	$ 59,929	$ 17,938
[1] Amounts reclassified from comprehensive income to interest expense within the Consolidated Statements of Operations.

CONSOLIDATED STATEMENTS OF PART

CONSOLIDATED STATEMENTS OF PARTNERS’ EQUITY - USD ($) $ in Thousands	Total	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest - Consolidated Real Estate Ventures	BRANDYWINE OPERATING PARTNERSHIP, L.P.	BRANDYWINE OPERATING PARTNERSHIP, L.P. Accumulated Other Comprehensive Income (Loss)	BRANDYWINE OPERATING PARTNERSHIP, L.P. Noncontrolling Interest - Consolidated Real Estate Ventures	BRANDYWINE OPERATING PARTNERSHIP, L.P. General Partner Capital
Beginning balance (in shares) at Dec. 31, 2020							170,572,964
Beginning balance at Dec. 31, 2020				$ 1,793,082	$ (7,935)	$ 72	$ 1,800,945
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 12,366		$ 77	12,366		(3)	$ 12,369
Other comprehensive income	5,569	$ 5,541	28	5,569	5,569
Deferred compensation obligation (in shares)							(18,058)
Deferred compensation obligation	(198)			(198)			$ (198)
Issuance of LP Units (in shares)							226,695
Issuance of LP Units				3,052			$ 3,052
Repurchase and retirement of LP units				(2,334)			$ (2,334)
Issuance of partnership interest in consolidated real estate venture	2,765		2,765	2,765		2,765
Share-based compensation activity (in shares)							344,656
Share-based compensation activity	6,354			6,354			$ 6,354
Adjustment of redeemable partnership units to liquidation value at period end				(232)			(232)
Distributions declared to general partnership unitholders				(130,345)			$ (130,345)
Ending balance (in shares) at Dec. 31, 2021							171,126,257
Ending balance at Dec. 31, 2021				1,690,079	(2,366)	2,834	$ 1,689,611
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	53,992		168	53,992		(2)	$ 53,994
Other comprehensive income	5,935	5,917	18	5,935	5,935
Deferred compensation obligation (in shares)							(25,979)
Deferred compensation obligation	(312)			(312)			$ (312)
Repurchase and retirement of LP units				(4,006)			$ (4,006)
Share-based compensation activity (in shares)							469,529
Share-based compensation activity	7,718			7,718			$ 7,718
Adjustment of redeemable partnership units to liquidation value at period end				7,555			7,555
Distributions declared to general partnership unitholders				(130,822)			$ (130,822)
Ending balance (in shares) at Dec. 31, 2022							171,569,807
Ending balance at Dec. 31, 2022				1,630,139	3,569	2,832	$ 1,623,738
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(197,403)		(614)	(197,403)		(22)	$ (197,381)
Other comprehensive income	(4,579)	$ (4,565)	$ (14)	(4,579)	(4,579)
Deferred compensation obligation (in shares)							(17,690)
Deferred compensation obligation	(108)			(108)			$ (108)
Share-based compensation activity (in shares)							545,544
Share-based compensation activity	$ 10,880			10,880			$ 10,880
Adjustment of redeemable partnership units to liquidation value at period end				60			60
Distributions declared to general partnership unitholders				(117,617)			$ (117,617)
Ending balance (in shares) at Dec. 31, 2023							172,097,661
Ending balance at Dec. 31, 2023				$ 1,321,372	$ (1,010)	$ 2,810	$ 1,319,572

CONSOLIDATED STATEMENTS OF PA_2

CONSOLIDATED STATEMENTS OF PARTNERS’ EQUITY (Parenthetical) - BRANDYWINE OPERATING PARTNERSHIP, L.P. - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Distributions to general partnership unitholders (in dollars per share)			$ 0.76
General Partner Capital
Distributions to general partnership unitholders (in dollars per share)	$ 0.68	$ 0.76

CONSOLIDATED STATEMENTS OF CA_3

CONSOLIDATED STATEMENTS OF CASH FLOWS - BRANDYWINE OPERATING PARTNERSHIP L.P. - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income (loss)	$ (197,403)	$ 53,992	$ 12,366
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	188,797	177,984	178,105
Amortization of deferred financing costs	4,369	3,091	2,836
Amortization of debt discount/(premium), net	(1,056)	(5,254)	(1,951)
Amortization of stock compensation costs	9,847	8,939	7,130
Straight-line rent income	(9,270)	(13,631)	(13,485)
Amortization of acquired above (below) market leases, net	(1,256)	(2,581)	(5,377)
Straight-line ground rent expense	799	814	918
Net gain on real estate venture transactions	(181)	(26,718)	(2,973)
Total gain on sale of real estate	(8,947)	(25,684)	(3,045)
Gain (loss) on early extinguishment of debt	(138)	435	0
Provision for impairment	131,573	4,663	0
Loss from unconsolidated real estate ventures, including income distributions	77,915	23,522	26,697
Income tax provision	72	55	47
Changes in assets and liabilities:
Accounts receivable	241	1,328	2,506
Other assets	(2,831)	(1,120)	(19,325)
Accounts payable and accrued expenses	(12,928)	5,405	2,974
Deferred income, gains and rent	(86)	1,567	2,986
Other liabilities	(2,244)	2,500	465
Net cash provided by operating activities	177,273	209,307	190,874
Cash flows from investing activities:
Acquisition of properties	(7,747)	(3,446)	0
Proceeds from the sale of properties	76,804	64,210	10,303
Proceeds from insurance	0	0	1,250
Proceeds from note receivable	0	44,300	50,000
Capital expenditures for tenant improvements	(48,939)	(86,774)	(56,830)
Capital expenditures for redevelopments	(59,984)	(87,223)	(48,022)
Capital expenditures for developments	(47,537)	(89,017)	(30,269)
Advances for the purchase of tenant assets, net of repayments	(998)	(447)	270
Investment in unconsolidated real estate ventures	(85,922)	(47,428)	(31,643)
Deposits for real estate	3,500	(4,900)	(2,550)
Capital distributions from unconsolidated real estate ventures	3,790	46,898	27,028
Leasing costs paid	(7,879)	(26,762)	(19,852)
Net cash used in investing activities	(174,912)	(190,589)	(100,315)
Cash flows from financing activities:
Proceeds from credit facility borrowings	215,000	478,000	154,000
Repayments of credit facility borrowings	(303,500)	(412,500)	(131,000)
Proceeds from unsecured notes	0	350,000	0
Repayments of unsecured notes	(64,164)	(296,134)	0
Proceeds from unsecured term loan	70,000	0	0
Proceeds from secured term loan	245,000	0	0
Proceeds from construction loan	13,824	0	0
Debt financing costs paid	(4,371)	(9,875)	0
Exercise of stock options, net	0	0	(63)
Shares used for employee taxes upon vesting of share awards	(371)	(2,941)	(1,762)
Partner contributions to consolidated real estate venture	0	0	2,765
Redemption of limited partnership units	(5)	(4,006)	(2,334)
Distributions paid to preferred and common partnership units	(124,255)	(130,724)	(130,255)
Net cash provided by (used in) financing activities	46,786	(28,631)	(109,336)
Increase/(Decrease) in cash and cash equivalents and restricted cash	49,147	(9,913)	(18,777)
Cash and cash equivalents and restricted cash at beginning of year	18,387	28,300	47,077
Cash and cash equivalents and restricted cash at end of period	67,534	18,387	28,300
Reconciliation of cash and cash equivalents and restricted cash:
Cash and cash equivalents, beginning of period	17,551	27,463	46,344
Restricted cash, beginning of period	836	837	733
Cash and cash equivalents, end of period	58,319	17,551	27,463
Restricted cash, end of period	9,215	836	837
Cash and cash equivalents and restricted cash	67,534	18,387	28,300
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the years ended December 31, 2023, 2022 and 2021 of $16,410, $10,517 and $8,689 respectively	107,838	85,761	72,391
Cash paid for income taxes	550	902	785
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	26,017	32,792	32,765
Extinguishment of debt costs accrued in financing activities	0	393	0
Change in investment in real estate ventures as a result of deconsolidation	8,595	107,057	32,761
Change in operating real estate from deconsolidation of operating properties	(7,814)	(92,009)	(30,073)
Change in other assets as a result of deconsolidation of operating properties	0	(15,048)	(2,688)
Change in capital expenditures financed through accounts payable at period end	(3,282)	(6,135)	22,744
Change in capital expenditures financed through retention payable at period end	2,715	(7,165)	(613)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Cash flows from operating activities:
Net income (loss)	(197,403)	53,992	12,366
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	188,797	177,984	178,105
Amortization of deferred financing costs	4,369	3,091	2,836
Amortization of debt discount/(premium), net	(1,056)	(5,254)	(1,951)
Amortization of stock compensation costs	9,847	8,939	7,130
Straight-line rent income	(9,270)	(13,631)	(13,485)
Amortization of acquired above (below) market leases, net	(1,256)	(2,581)	(5,377)
Straight-line ground rent expense	799	814	918
Net gain on real estate venture transactions	(181)	(26,718)	(2,973)
Total gain on sale of real estate	(8,947)	(25,684)	(3,045)
Gain (loss) on early extinguishment of debt	(138)	435	0
Provision for impairment	131,573	4,663	0
Loss from unconsolidated real estate ventures, including income distributions	77,915	23,522	26,697
Income tax provision	72	55	47
Changes in assets and liabilities:
Accounts receivable	241	1,328	2,506
Other assets	(2,831)	(1,120)	(19,325)
Accounts payable and accrued expenses	(12,928)	5,405	2,974
Deferred income, gains and rent	(86)	1,567	2,986
Other liabilities	(2,244)	2,500	465
Net cash provided by operating activities	177,273	209,307	190,874
Cash flows from investing activities:
Acquisition of properties	(7,747)	(3,446)	0
Proceeds from the sale of properties	76,804	64,210	10,303
Proceeds from insurance	0	0	1,250
Proceeds from note receivable	0	44,300	50,000
Capital expenditures for tenant improvements	(48,939)	(86,774)	(56,830)
Capital expenditures for redevelopments	(59,984)	(87,223)	(48,022)
Capital expenditures for developments	(47,537)	(89,017)	(30,269)
Advances for the purchase of tenant assets, net of repayments	(998)	(447)	270
Investment in unconsolidated real estate ventures	(85,922)	(47,428)	(31,643)
Deposits for real estate	3,500	(4,900)	(2,550)
Capital distributions from unconsolidated real estate ventures	3,790	46,898	27,028
Leasing costs paid	(7,879)	(26,762)	(19,852)
Net cash used in investing activities	(174,912)	(190,589)	(100,315)
Cash flows from financing activities:
Proceeds from credit facility borrowings	215,000	478,000	154,000
Repayments of credit facility borrowings	(303,500)	(412,500)	(131,000)
Proceeds from unsecured notes	0	350,000	0
Repayments of unsecured notes	(64,164)	(296,134)	0
Debt financing costs paid	(4,371)	(9,875)	0
Exercise of stock options, net	0	0	(63)
Shares used for employee taxes upon vesting of share awards	(371)	(2,941)	(1,762)
Partner contributions to consolidated real estate venture	0	0	2,765
Redemption of limited partnership units	(5)	(4,006)	(2,334)
Distributions paid to preferred and common partnership units	(124,627)	(131,175)	(130,942)
Net cash provided by (used in) financing activities	46,786	(28,631)	(109,336)
Increase/(Decrease) in cash and cash equivalents and restricted cash	49,147	(9,913)	(18,777)
Cash and cash equivalents and restricted cash at beginning of year	18,387	28,300	47,077
Cash and cash equivalents and restricted cash at end of period	67,534	18,387	28,300
Reconciliation of cash and cash equivalents and restricted cash:
Cash and cash equivalents, beginning of period	17,551	27,463	46,344
Restricted cash, beginning of period	836	837	733
Cash and cash equivalents, end of period	58,319	17,551	27,463
Restricted cash, end of period	9,215	836	837
Cash and cash equivalents and restricted cash	67,534	18,387	28,300
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the years ended December 31, 2023, 2022 and 2021 of $16,410, $10,517 and $8,689 respectively	107,838	85,761	72,391
Cash paid for income taxes	550	902	785
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	26,017	32,792	32,765
Extinguishment of debt costs accrued in financing activities	0	393	0
Change in investment in real estate ventures as a result of deconsolidation	8,595	107,057	32,761
Change in operating real estate from deconsolidation of operating properties	(7,814)	(92,009)	(30,073)
Change in other assets as a result of deconsolidation of operating properties	0	(15,048)	(2,688)
Change in capital expenditures financed through accounts payable at period end	(3,282)	(6,135)	22,744
Change in capital expenditures financed through retention payable at period end	$ 2,715	$ (7,165)	$ (613)

CONSOLIDATED STATEMENTS OF CA_4

CONSOLIDATED STATEMENTS OF CASH FLOWS - BRANDYWINE OPERATING PARTNERSHIP L.P. (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Cash Flows [Abstract]
Capitalized interest	$ 16,410	$ 10,517	$ 8,689

ORGANIZATION OF THE PARENT COMP

ORGANIZATION OF THE PARENT COMPANY AND THE OPERATING PARTNERSHIP	12 Months Ended
	Dec. 31, 2023
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 December 31, 2023, owned a 99.7% 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 December 31, 2023, the Company owned 72 properties that contained an aggregate of approximately 13.0 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 December 31, 2023: Number of Properties Rentable Square Feet Office properties 65 11,773,665 Mixed-use properties 4 924,450 Core Properties 69 12,698,115 Development property 2 144,685 Recently completed - not stabilized property 1 168,294 The Properties 72 13,011,094 In addition to the Properties, as of December 31, 2023, the Company owned 141.6 acres of land held for development. The Company also held a leasehold interest in one land parcel totaling 0.8 acres, acquired through a prepaid 99-year ground lease, and held options to purchase approximately 5.1 additional acres of undeveloped land. As of December 31, 2023, 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 12.1 million square feet. As of December 31, 2023, the Company also owned economic interests in twelve unconsolidated real estate ventures (see Note 4 “Investment in Unconsolidated Real Estate Ventures” for further information). The Properties and the properties owned by the unconsolidated real estate ventures are primarily located in or near Philadelphia, Pennsylvania; Austin, Texas; Washington, D.C.; Southern New Jersey; and Wilmington, Delaware. All references to building square footage, rentable square feet, acres, occupancy percentage, the number of buildings, and tax basis are unaudited. The Company conducts its third-party real estate management services business primarily through seven management companies (collectively, the “Management Companies”): Brandywine Realty Services Corporation (“BRSCO”), BDN Management Inc. (“BMI”), Brandywine Properties I Limited, Inc. (“BPI”), BDN Brokerage, LLC (“BBL”), Brandywine Properties Management, L.P. (“BPM”), Brandywine Brokerage Services, LLC (“BBS”), and BDN GC Services LLC (“BGCS”). Each of BRSCO, BMI and BPI is a taxable REIT subsidiary. BBS, BBL, BPM, and BGCS are tax disregarded entities wholly owned by the taxable REIT subsidiary entities. As of December 31, 2023, the Operating Partnership owned, directly and indirectly, 100% of each of BRSCO, BMI, BPI, BBL, BPM, BBS, and BGCS. As of December 31, 2023, the Management Company subsidiaries were managing properties containing an aggregate of approximately 22.4 million net rentable square feet, of which approximately 13.0 million net rentable square feet related to Properties owned by the Company and approximately 9.4 million net rentable square feet related to properties owned by third parties and unconsolidated real estate ventures.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Principles of Consolidation The Company consolidates variable interest entities (“VIEs”) in which it is considered to be the primary beneficiary. VIEs are entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial support or that the holders of the equity investment at risk do not have a controlling financial interest. The primary beneficiary is defined by the entity having both of the following characteristics: (i) the power to direct those matters that most significantly impact the activities of the VIE and (ii) the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE. For entities that the Company has the obligations to fund losses, its maximum exposure to loss is not limited to the carrying amount of its investments. The Company continuously assesses its determination of the primary beneficiary for each entity and assesses reconsideration events that may cause a change in the original determinations. As of December 31, 2023 and 2022, the Company included in its consolidated balance sheets consolidated VIEs having total assets of $34.4 million and $47.3 million, respectively, and total liabilities of $21.5 million and $21.0 million, respectively. When an entity is not deemed to be a VIE, the Company consolidates entities for which it has significant decision making control over the entity’s operations. The Company’s judgment with respect to its level of influence or control of an entity involves consideration of various factors including the form of the Company’s ownership interest, its representation in the entity’s governance, the size of its investment (including loans), estimates of future cash flows, its ability to participate in policy making decisions and the rights of the other investors to participate in the decision making process and to replace the Company as manager and/or liquidate the venture, if applicable. The Company’s assessment of its influence or control over an entity affects the presentation of these investments in the Company’s consolidated financial statements. In addition to evaluating control rights, the Company consolidates entities in which the outside partner has no substantive kick-out rights to remove the Company as managing member. The portion of the consolidated entities that are not owned by the Company is presented as noncontrolling interest as of and during the periods consolidated. All intercompany transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. Operating Properties Operating properties are carried at historical cost less accumulated depreciation and impairment losses. The value of operating properties reflects their purchase price or development cost. Acquisition costs related to business combinations are expensed as incurred, whereas the costs related to asset acquisitions are capitalized as incurred. Costs incurred for the renovation and betterment of an operating property are capitalized to the Company’s investment in that property. Ordinary repairs and maintenance are expensed as incurred. Purchase Price Allocation For acquisitions of real estate or in-substance real estate that are accounted for as business combinations, we recognize the assets acquired (including the intangible value of acquired above- or below-market leases, acquired in-place leases and tenant relationship values), liabilities assumed, noncontrolling interests, and previously existing ownership interests at fair value as of the acquisition date. Any excess (deficit) of the consideration transferred relative to the fair value of the net assets acquired is accounted for as goodwill (bargain purchase gain). Acquisition costs related to business combinations are expensed as incurred. Acquisitions of real estate and in-substance real estate that do not meet the definition of a business are accounted for as asset acquisitions. The Company generally expects that acquisitions of real estate or in-substance real estate will not meet the definition of business and therefore are accounted for as asset acquisitions, unless specifically noted otherwise. The accounting model for asset acquisitions is similar to the accounting model for business combinations except that the acquisition consideration (including acquisition costs) is allocated to the individual assets acquired and liabilities assumed on a relative fair value basis. As a result, asset acquisitions do not result in recognition of goodwill or a bargain purchase gain. Additionally, because the accounting model for asset acquisitions is a cost accumulation model, preexisting interests in the acquired assets, if any, are not remeasured to fair value but continue to be accounted for at their historical cost. Direct acquisition costs are capitalized if an asset acquisition is probable. If we determine that an asset acquisition is no longer probable, no new costs are capitalized and all capitalized costs that are not recoverable are written off. The purchase price is allocated to the acquired assets and assumed liabilities, including land and buildings, as if vacant based on highest and best use for the acquired assets. The Company assesses and considers fair value of the operating properties based on estimated cash flow projections that utilize discount and/or capitalization rates that it deems appropriate, as well as available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known and anticipated trends, and market and economic conditions. The Company allocates the purchase price of properties considered to be business combinations and asset acquisitions to net tangible and identified intangible assets acquired based on fair values. Above-market and below-market in-place lease values for acquired properties are recorded based on the present value (using an interest rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to the in-place leases and (ii) the Company’s estimate of the fair market lease rates for the corresponding in-place leases, measured over a period equal to the remaining noncancellable term of the lease (including the below market fixed renewal periods that are considered probable, if applicable). Capitalized above-market lease values are amortized as a reduction of rental income over the remaining noncancellable terms of the respective leases. Capitalized below-market lease values are amortized as an increase to rental income over the remaining noncancellable terms of the respective leases, including any below market fixed-rate renewal option periods that are considered probable. Other intangible assets also include in-place leases based on the Company’s evaluation of the specific characteristics of each tenant’s lease and the Company’s overall relationship with the respective tenant. The Company estimates the cost to execute leases with terms similar to the remaining lease terms of the in-place leases, including leasing commissions, legal and other related expenses. This intangible asset is amortized to expense over the remaining term of the respective leases and any fixed-rate bargain renewal periods. Factors considered by the Company in this analysis include an estimate of the carrying costs during the expected lease-up periods considering current market conditions and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance, and other operating expenses, and estimates of lost rents at market rates during the expected lease-up periods, which primarily range from four In the event that a tenant terminates its lease, the unamortized portion of each intangible, including in-place lease values and tenant relationship values, is charged to expense and market rate adjustments (above or below) are recorded to revenue. Depreciation and Amortization The costs of buildings and improvements are depreciated using the straight-line method based on the following useful lives: buildings and improvements (5 to 55 years) and tenant improvements (the shorter of (i) the life of the asset (1 to 16 years) or (ii) the lease term). Construction-in-Progress Project costs directly associated with the development or redevelopment and construction of a real estate project are capitalized as construction-in-progress. Construction-in-progress also includes costs related to ongoing tenant improvement projects. In addition, interest, real estate taxes, and other expenses that are directly associated with the Company’s development or redevelopment activities are capitalized beginning when activities necessary to ready the asset for its intended use are in progress and capital expenditures have been made and ending when the property is placed in service. Interest expense is capitalized using the Company’s weighted average interest rate. Internal direct costs are capitalized to projects in which qualifying expenditures are being incurred. See Note 3 “Real Estate Investments,” for more information related to the capitalization of project costs. Ground Leases The Company is the lessee under long-term ground leases classified as operating leases. The Company makes significant assumptions and judgments when determining the discount rate for the lease to calculate the present value of the lease payments. As the rate implicit in the lease is not readily determinable, the Company estimates the incremental borrowing rate (“IBR”) that it would need to pay to borrow, on a collateralized basis, an amount equal to the lease payments in a similar economic environment, over a similar lease term. The Company utilizes a market-based approach to estimate the IBR for each individual lease. The base IBR is estimated utilizing observable mortgage and corporate bond rates, which are then adjusted to account for considerations related to the Company’s credit rating and the lease term to select an incremental borrowing rate for each lease. The right of use assets and lease liabilities are presented as “Right of use asset - operating leases, net” and “Lease liability - operating leases”, respectively, on the consolidated balance sheet as of December 31, 2023 and 2022, respectively. The lease liabilities and right of use assets are amortized on a straight-line basis over the lease term with the corresponding expense classified in “Property operating expenses” on the consolidated statements of operations. The most recent CPI adjustment is used to determine the present value of the lease payments for an indexed lease and ultimately the right of use asset and corresponding lease liability. Rent payments for amounts in excess of this estimated growth rate will be expensed on a cash basis as incurred and are considered variable lease costs. Impairment of Real Estate Investments The Company reviews its real estate investments for impairment following the end of each quarter for each of its real estate investments where events or changes in circumstances indicate that the carrying amounts may not be recoverable. The Company updates leasing and other assumptions regularly, paying particular attention to real estate investments where there is an event or change in circumstances that indicates an impairment in value. Additionally, the Company considers strategic decisions regarding the future development plans for real estate investment under development and other market factors. For real estate investments to be held and used, the Company analyzes recoverability based on the estimated undiscounted future cash flows expected to be generated from the operations and eventual disposition of the assets over, in most cases, a 10-year hold period. If there is significant possibility that the Company will dispose of assets earlier, it analyzes the recoverability using a probability weighted analysis of the undiscounted future cash flows expected to be generated from the operations and eventual disposition of each asset using various probable hold periods. If the recoverability analysis indicates that the carrying value of the tested real estate investment is not recoverable, the real estate investment is written down to its fair value and an impairment is recognized in the amount of the excess of the carrying amount of the asset over its fair value. If and when the Company’s plans change, it revises its recoverability analysis to use cash flows expected from operations and eventual disposition of each asset using hold periods that are consistent with its revised plans. Estimated future cash flows used in such analysis are based on the Company’s plans for the real estate investment and its views of market economic conditions. The estimates consider assumptions, including but not limited to market rental rates, capitalization rates, and recent sales data for comparable real estate investments. Future cash flows are discounted when determining fair value of an asset. Most of these assumptions are influenced by our direct experience with the real estate investments and their markets as well as market data obtained from real estate leasing and brokerage firms. Assets Held for Sale The Company generally reclassifies assets to held for sale when the transaction has been approved by its Board of Trustees, or by officers vested with authority to approve the transaction, and there are no known significant contingencies relating to the sale of the real estate investment within one year of the consideration date and the consummation of the transaction is otherwise considered probable. When a real estate investment is designated as held for sale, the Company stops depreciating the real estate investment and estimates the real estate investment’s fair value, net of selling costs. If the determination is made that the estimated fair value, net of selling costs, is less than the net carrying value of the real estate investment, an impairment is recognized, reducing the net carrying value of the real estate investment to estimated fair value less selling costs. For periods in which a real estate investment is classified as held for sale, the Company classifies the assets and liabilities, as applicable, of the real estate investment as held for sale on the consolidated balance sheet for such periods. Impairment of Land Held for Development When demand for build-to-suit properties declines and the ability to sell land held for development deteriorates, or other market factors indicate possible impairment in the recoverability of land held for development, it is reviewed for impairment by comparing its fair value to its carrying value. If the estimated sales value is less than the carrying value, the carrying value is written down to its estimated fair value. Estimated fair value is generally determined using a market valuation approach, comparing the subject property to recent comparable market transactions in a similar location; or using estimated cash flows. Cash and Cash Equivalents Cash and cash equivalents are highly-liquid investments with original maturities of three months or less. The Company maintains cash equivalents in money market accounts with financial institutions in excess of insured limits, but believes this risk is mitigated by only investing in or through major financial institutions. The Company does not invest its available cash balances in money market funds. As such, available cash balances are appropriately reflected as cash and cash equivalents on the consolidated balance sheets. Restricted Cash and Escrows Restricted cash and escrows primarily consists of security deposits held on behalf of our tenants, interest reserves, as well as capital improvement and real estate tax escrows required under certain loan agreements. Restricted cash also includes cash held by qualified intermediaries for possible investments in like-kind exchanges in accordance with Section 1031 of the Internal Revenue Code in connection with sales of the Company’s properties. Accounts Receivable and Accrued Rent Receivable Generally, leases with tenants are accounted for as operating leases. Minimum lease payments under tenant leases are recognized on a straight-line basis over the term of the related lease. The cumulative difference between lease revenue recognized under the straight-line method and contractual lease payment terms are recorded as “Accrued rent receivable, net” on the consolidated balance sheets. Included in current tenant receivables are tenant reimbursements which are comprised of amounts recoverable from tenants for common area maintenance expenses and certain other recoverable expenses that are recognized as revenue in the period in which the related expenses are incurred. Accrued rent receivables are carried net of the allowances for doubtful accounts. The allowance for doubtful accounts is an estimate based on the Company's experience of the probability of future events confirming a loss and represents the estimated probable losses. The allowance is generally calculated by assigning risk factors by industry which are primarily based on the Company's historical collection and charge-off experience adjusted for current market conditions, which requires management's judgment. Investments in Unconsolidated Real Estate Ventures Under the equity method, investments in real estate ventures are recorded initially at cost and subsequently adjusted for equity in earnings, contributions, distributions, and impairments. The Company generally allocates income and losses from the unconsolidated real estate ventures based on the venture's distribution priorities, which may be different from its stated ownership percentage. For real estate ventures that are constructing assets to commence planned principal operations, the Company capitalizes interest expense to the extent that it is recoverable using the Company’s weighted average interest rate of consolidated debt and its investment balance as a basis. Planned principal operations commence when a property is available to lease and at that point in time, the Company ceases capitalizing interest to its investment basis. At least quarterly, management assesses whether there are any other than temporary impairment indicators of the Company’s investments in real estate ventures. If any indicators of impairment are present, we calculate the fair value of the investment in the unconsolidated real estate venture. An investment is other than temporarily impaired only if the fair value of the investment in a real estate venture, as estimated by management, is less than the carrying value and the decline is other than temporary. To the extent that an other than temporary impairment has occurred, an impairment charge is recorded in the amount of the excess of the carrying amount of the investment over the estimated fair value. Management is required to make significant judgments about the estimated fair value of its investments to determine if an impairment exists. Fair value is generally determined through income valuation approaches, including discounted cash flows and direct capitalization models or a sales comparison approach. When the Company acquires an interest in or contributes assets to a real estate venture project, the difference between the Company’s cost basis in the investment and the value of the real estate venture or asset contributed is amortized over the life of the related assets, intangibles, and liabilities and such adjustment is included in the Company’s share of equity in income of unconsolidated real estate ventures. Deferred Costs Certain costs incurred in connection with property leasing are capitalized as deferred leasing costs. Deferred leasing costs consist primarily of third-party and internal leasing commissions that are amortized using the straight-line method over the life of the respective lease which generally ranges from 1 to 16 years. Management re-evaluates the remaining useful lives of leasing costs in conjunction with changes in the respective lease term. Notes Receivable The Company accounts for notes receivable on its balance sheet at amortized cost, net of allowance for loan losses. Interest income is recognized over the term of the notes receivable and is calculated based on the contractual terms of each note agreement. At inception and on a quarterly basis, the Company evaluates notes receivable for the current estimate of expected credit losses over the contractual term using a probability-of-default method and reports in net income (as a credit loss expense) the amount necessary to adjust the allowance for credit losses to reflect management's current estimate. Management considers performance and/or value of the underlying collateral property as well as the financial and operating capability of the borrower/sponsor in its evaluation. Notes receivable are placed on nonaccrual status when management determines, after considering economic and business conditions and collection efforts, that the loans are impaired, or collection of interest is doubtful. Uncollectible interest previously accrued is recognized as bad debt expense. Interest income on nonaccrual loans is recognized only to the extent that cash payments are received. Deferred Financing Costs Costs incurred in connection with debt financing are capitalized as a direct deduction from the carrying value of the debt, except for costs capitalized related to the Company’s unsecured credit facility, which are capitalized within the “Deferred costs, net” caption on the accompanying consolidated balance sheets. Deferred financing costs are charged to interest expense over the terms of the related debt agreements. Deferred financing costs consist primarily of loan fees which are amortized over the related loan term on a basis that approximates the effective interest method. Deferred financing costs are accelerated, when debt is extinguished, as part of the “Interest expense-amortization of deferred financing costs” caption within the Company’s consolidated statements of operations. Original issue discounts are recognized as part of the gain or loss on extinguishment of debt, as appropriate. Revenue Recognition Rental Revenue The Company generates revenue under leases with tenants occupying the Properties. Generally, leases with tenants are accounted for as operating leases. The operating leases have various expiration dates. As of December 31, 2023 and 2022, the Company did not have any leases classified as direct-financing or sales-type leases. Fixed lease payments under tenant leases, determined to be collectible, are recognized on a straight-line basis over the term of the related lease. The cumulative difference between lease revenue recognized under the straight-line method and contractual lease payments are recorded as “Accrued rent receivable” on the consolidated balance sheets. Variable lease payments are recognized as lease revenue in the period in which changes occur in facts and circumstances on which the variable lease payments are based. Topic 842 requires a binary approach to evaluating leases for collectability. Lessors are required to determine if it is probable that substantially all of the lease payments will be collected from the tenant over the lease term. Should the lessor determine that it is not probable that substantially all of the lease payments will be collected, the standard requires that the lessor write off any accrued rent receivable and begin recognizing lease payments on a cash basis. The Company’s lease revenue is impacted by the Company’s determination of whether improvements to the property, whether made by the Company or by the tenant, are landlord assets. The determination of whether an improvement is a landlord asset requires judgment. In making this judgment, the Company’s primary consideration is whether an improvement would be utilizable by another tenant upon the then-existing tenant vacating the improved space. If the Company has funded an improvement that it determines not to be landlord assets, then it treats the cost of the improvement as a lease incentive. If the tenant has funded an improvement that the Company determines to be landlord assets, then the Company treats the costs of the improvement as deferred revenue and amortizes these costs into revenue over the lease term. For certain leases, the Company also makes significant assumptions and judgments in determining the lease term, including assumptions when the lease provides the tenant with an early termination option or purchase option. The lease term impacts the period over which the Company determines and records lease payments and also impacts the period over which it amortizes lease-related costs. The Company considers all relevant factors that create an economic incentive for the lessee and uses judgment to determine if those factors, considered together, signify that the lessee is reasonably certain to exercise the option. For leases where a tenant executes a lease termination, termination fees are generally recognized over the modified term of the lease as rental income. Additionally, any deferred rents receivable are accelerated over the modified lease term. The Company’s leases also typically provide for tenant reimbursement of a portion of common area maintenance expenses and other operating expenses to the extent that a tenant’s pro rata share of expenses exceeds a base year level set in the lease or to the extent that the tenant has a lease on a triple net basis. As the timing and pattern of revenue recognition is the same, rents and tenant reimbursements are treated as a combined lease component and included in the “Rents” caption within the Company's consolidated statements of operations. Fixed lease payments include contractual rents under lease agreements with tenants recognized on a straight-line basis over the lease term, including amortization of lease incentives and above or below market rent intangibles, and parking income that is fixed under a long-term contract. Variable lease payments include reimbursements billed to tenants, termination fees, bad debt expense, and parking income that is not fixed under a long-term contract. Point of Sale Revenue Point of sale revenue consists of parking, restaurant, and flexible stay revenue from the Company’s hotel operations. Point of sale service obligations are performed daily, and the customer obtains control of those services simultaneously as they are performed. Accordingly, revenue is recorded on an accrual basis as it is earned, coinciding with the services that are provided to the Company’s customers. Parking and flexible stay revenue is recognized within rents and restaurant income is recognized within other income on the consolidated statements of operations. Third party management fees, labor reimbursement, and leasing The Company performs property management services for its managed real estate ventures and third-party property owners of real estate that consist of: (i) providing leasing services, (ii) property inspections, (iii) repairs and maintenance monitoring, and (iv) financial and accounting oversight. For these services, the Company earns management fees monthly, which are based on a fixed percentage of each managed property’s financial results, and is reimbursed for the labor costs incurred by its property management employees as services are rendered to the property owners. The Company determined that control over the services is passed to its customers simultaneously as performance occurs. Accordingly, management fee revenue is earned as the services are provided to the Company’s customers. Lease commissions are earned when the Company, as a broker for the third party property owner, executes a lease agreement with a tenant. Based on the terms of the Company’s lease commission contracts, the Company's performance obligation to the customer has been completed upon execution of each lease agreement. The Company’s lease commissions are earned based on a fixed percentage of rental income generated for each executed lease agreement and there is no variable income component. Development fee revenue is earned through two different sources: (i) the Company performs development services for third parties as an agent and earns fixed development fees based on a percentage of construction costs incurred over the construction period, and (ii) the Company acts as a general contractor on behalf of one of its managed real estate ventures. The Company acts as the principal construction company for the real estate ventures and records gross revenue as it provides construction services based on the quantifiable construction outputs. In applying the cost based output method of revenue recognition, the Company uses the actual costs incurred relative to the total estimated costs to determine its progress towards contract completion and to calculate the corresponding gross revenue and gross profit to recognize. For any costs that do not contribute to satisfying the Company’s performance obligations, it excludes such costs from its output methods of revenue recognition as the amounts are not reflective of transferring control of the outputs to the customer. The use of estimates in this calculation involves significant judgment. Common Development Cost Estimates for Contributions to Development Joint Ventures When land is contributed to a development joint venture, estimated common development costs include actual costs incurred and estimates of future common development costs benefiting the property sold. When land is sold, common development costs, if they cannot be specifically identified, are allocated to each sold parcel based upon its relative sales value. For purposes of allocating common development costs, estimates of future sales proceeds and common development costs are re-evaluated throughout the year, with adjustments being allocated prospectively to the remaining land parcels available for sale. The common development cost estimates for development joint ventures are highly judgmental as they are sensitive to cost escalation, sales price escalation and pace of absorption, which are subject to judgment and are affected by expectations about future market or economic conditions. Changes in the assumptions used to estimate future common development costs could result in a significant impact on the amounts recorded as net gain on disposition of real estate or net gain on sale of undepreciated real estate. The following is a summary of revenue earned by the Company’s reportable segments (see Note 19 “Segment Information,” for further information) during the year ended December 31, 2023 (in thousands): Philadelphia CBD Pennsylvania Suburbs Austin, Texas Other Corporate (a) Total Fixed rent $ 159,732 $ 118,856 $ 63,209 $ 32,167 $ (1,895) $ 372,069 Variable rent 54,678 10,067 30,098 1,681 454 96,978 Total lease revenue 214,410 128,923 93,307 33,848 (1,441) 469,047 Amortization of deferred market rents 649 — 642 — — 1,291 Daily parking & hotel flexible stay 8,478 — 708 325 — 9,511 Total rents 223,537 128,923 94,657 34,173 (1,441) 479,849 Third party management fees, labor reimbursement and leasing 405 38 516 4,972 18,486 24,417 Other income 6,991 339 332 161 2,562 10,385 Total revenue $ 230,933 $ 129,300 $ 95,505 $ 39,306 $ 19,607 $ 514,651 (a) Corporate includes intercompany eliminations necessary to reconcile to consolidated Company totals. The following is a summary of revenue earned by the Company’s reportable segments (see Note 19 “Segment Information,” for further information) during the year ended December 31, 2022 (in thousands): Philadelphia CBD Pennsylvania Suburbs Austin, Texas Other Corporate (a) Total Fixed rent $ 151,034 $ 116,926 $ 60,831 $ 26,491 $ (1,895) $ 353,387 Variable rent 51,346 11,615 32,958 3,927 (35) 99,811 Total lease revenue 202,380 128,541 93,789 30,418 (1,930) 453,198 Amortization of deferred market rents 1,308 10 1,264 — — 2,582 Daily parking & hotel flexible stay 14,390 — 361 320 — 15,071 Total rents 218,078 128,551 95,414

REAL ESTATE INVESTMENTS

REAL ESTATE INVESTMENTS	12 Months Ended
	Dec. 31, 2023
Real Estate [Abstract]
REAL ESTATE INVESTMENTS	3. REAL ESTATE INVESTMENTS As of December 31, 2023 and 2022, the gross carrying value of the operating properties was as follows (in thousands): December 31, 2023 December 31, 2022 Land $ 394,669 $ 403,998 Building and improvements 2,671,024 2,760,357 Tenant improvements 476,539 452,885 Total $ 3,542,232 $ 3,617,240 Construction-in-Progress Internal direct construction costs totaling $8.9 million in 2023, $9.3 million in 2022, and $7.9 million in 2021 and interest totaling $5.2 million in 2023, $4.7 million in 2022, and $7.0 million in 2021 were capitalized related to the development, redevelopment and construction of tenant improvements of certain properties and land holdings. During the years ended December 31, 2023, 2022 and 2021, the Company’s internal direct construction costs are comprised of capitalized salaries. The following table shows the amount of compensation costs (including bonuses and benefits) capitalized for the years presented (in thousands): December 31, 2023 2022 2021 Development $ 4,096 $ 5,343 $ 4,815 Redevelopment 944 1,484 1,170 Tenant Improvements 3,817 2,505 1,917 Total $ 8,857 $ 9,332 $ 7,902 2023 Acquisitions Property/Portfolio Name Acquisition Date Location Property Type Rentable Square Feet/Acres Purchase Price 165 King of Prussia Road October 27, 2023 Radnor, PA Land 1.1 acres $ 8,550 2022 Acquisitions Property/Portfolio Name Acquisition Date Location Property Type Rentable Square Feet/Acres Purchase Price 631 Park Avenue January 21, 2022 King of Prussia, PA Land 3.3 acres $ 3,650 3151 Market Street (a) April 29, 2022 Philadelphia, PA Leasehold Interest 0.8 acres $ 27,349 (a) On April 29, 2022, the Company acquired, through a 99-year ground lease, the leasehold interest in a 0.8-acre land parcel, located at 3151 Market Street, in Philadelphia, Pennsylvania. The Company prepaid $19.5 million of the ground lease, representing 500,000 square feet of buildable floor to area ratio (“FAR”) to be used for the development of 3151 Market Street, and paid $7.8 million for 200,000 square feet of FAR density usable pursuant to the Schuylkill Yards Project master development agreement. The additional density is included in prepaid leasehold interests in land held for development in the consolidated balance sheets. See below regarding disposition of 500,000 square feet of FAR. 2021 Acquisitions During the year ended December 31, 2021, the Company did not acquire any properties from a third party. Dispositions The following table summarizes the property dispositions during the years ended December 31, 2023, 2022 and 2021 (dollars in thousands): Property/Portfolio Name Disposition Date Location Property Type Rentable Square Feet/Acres Sales Price Gain/(Loss) on Sale (a) Dabney East December 27, 2023 Richmond, VA Land 11.6 acres $ 1,600 $ 430 Byberry December 7, 2023 Philadelphia, PA Land Purchase Option 50.0 acres $ 9,641 $ 3,960 8521 Leesburg Pike (f) December 1, 2023 Vienna, VA Office 150,897 $ 11,000 $ — 200 N. Radnor Chester Road October 31, 2023 Radnor, PA Retail 17,884 $ 14,200 $ 7,735 Three Barton Skyway (f) August 4, 2023 Austin, TX Office 173,302 $ 53,250 $ — 200 Barr Harbor Drive November 22, 2022 West Conshohocken, PA Office 86,000 $ 30,500 $ 8,740 11501 Burnett Road (d) July 29, 2022 Austin, TX Land 4.7 acres $ 32,513 $ 8,340 3151 Market Street (c) July 14, 2022 Philadelphia, PA Leasehold Interest 0.8 acres $ 30,394 $ 2,583 Gibbsboro Portfolio (b) June 28, 2022 Gibbsboro, NJ Office/Land 42,809/4.0 acres $ 4,100 $ 831 25 M Street (e) April 14, 2022 Washington, D.C. Land 0.8 acres $ 29,675 $ 3,836 Gateway G & H January 20, 2022 Richmond, VA Land 10.0 acres $ 1,600 $ 897 1100 Lenox Drive September 8, 2021 Lawrenceville, NJ Land 5.0 acres $ 2,575 $ 68 2100-2200 Lenox Drive July 6, 2021 Lawrenceville, NJ Land 35.2 acres $ 8,900 $ 842 3025 JFK Boulevard February 2, 2021 Philadelphia, PA Leasehold Interest 1.0 acres $ 34,800 $ 2,000 (a) Gain/(Loss) on Sale is net of closing and other transaction related costs. (b) Includes $0.7 million of gain on sale of undepreciated real estate and $0.1 million of gain on disposition of real estate included within the consolidated statements of operations for the twelve months ended December 31, 2022. (c) On July 14, 2022, the Company contributed 500,000 square feet of FAR relating to its 99-year prepaid leasehold interest at 3151 Market Street in Philadelphia, Pennsylvania, acquired on April 29, 2022, to a newly formed joint venture with an unaffiliated third party. The Company's initial deemed contribution in the project was $30.4 million and the transaction resulted in deconsolidation of the property and conversion of Brandywine 3151 Market, LP, (formerly a wholly-owned subsidiary of the Operating Partnership) to a real estate venture (“3151 Market Street Venture”). The Company recorded its investment at fair value and recognized a gain, net of transaction costs, of $2.6 million, in “Net gain on sale of undepreciated real estate” on the consolidated statements of operations. See Note 4, “Investment in Unconsolidated Real Estate Ventures,” for further information. (d) On July 29, 2022, the Company contributed a 4.7 acre parcel of land held for development at 11501 Burnet Road in Austin, Texas to a newly formed joint venture with an unaffiliated third party. The project is part of the Uptown ATX master development. The Company's combined contributed initial land investment in the project was $32.5 million and the transaction resulted in the deconsolidation of the property and formation of Brandywine Uptown Office LLC and Brandywine One Uptown Multifamily LLC, (together, “One Uptown Ventures)”). The Company recorded its investment at fair value and recognized a gain of $8.3 million in “Net gain on disposition of real estate” on the consolidated statements of operations. Gain on sale of $8.3 million is calculated as the difference between the estimated relative sales value of the contributed land and the estimated total cost allocations per block. See Note 4, “Investment in Unconsolidated Real Estate Ventures,” for further information. (e) On September 30, 2022, the Company recognized $0.4 million of additional gain on disposition of real estate. (f) Recognized a provision for impairment of $16.7 million on the property prior to the sales. 3025 JFK Venture In addition, on February 2, 2021, the Company contributed its investment in a 99-year prepaid leasehold interest in a one-acre land parcel held for development at 3025 JFK Boulevard in Philadelphia, Pennsylvania to a newly formed joint venture with an unaffiliated third party. The project is part of the Schuylkill Yards master development. The Company's investment in the project was valued at $34.8 million and the transaction resulted in deconsolidation of the property and conversion of Brandywine Opportunity Fund, L.P. (formerly a wholly-owned subsidiary of the Operating Partnership) to a real estate venture ( “ 3025 JFK Venture ” ). The Company recorded its investment at fair value and recognized a gain of $2.0 million in “ Net gain on sale of undepreciated real estate ” on the consolidated statements of operations. See Note 4, “ Investment in Unconsolidated Real Estate Ventures, ” for further information. 3151 Market Venture On July 14, 2022, the Company contributed 500,000 square feet of FAR relating to its 99-year prepaid leasehold interest at 3151 Market Street in Philadelphia, Pennsylvania, acquired on April 29, 2022, to a newly formed joint venture with an unaffiliated third party. The Company's initial deemed contribution in the project was $30.4 million and the transaction resulted in deconsolidation of the property and conversion of Brandywine 3151 Market, LP, (formerly a wholly-owned subsidiary of the Operating Partnership) to a real estate venture (“3151 Market Street Venture”). The Company recorded its investment at fair value and recognized a gain, net of transaction costs, of $2.6 million, in “Net gain on sale of undepreciated real estate” on the consolidated statements of operations. See Note 4, “Investment in Unconsolidated Real Estate Ventures,” for further information. During the first quarter of 2023, the Company deconsolidated $7.8 million recorded in “Prepaid leasehold interests in land held for development, net” on the consolidated balance sheets. This deconsolidation reflects the Company’s contribution, in January 2023, of 200,000 square feet of buildable floor to area ratio (“FAR”) to the Company’s unconsolidated real estate venture, referred to in Note 4 below as the 3151 Market Street Venture, for use by this unconsolidated real estate venture in the development of 3151 Market Street. Upon contribution at fair market value, the Company recognized a gain, net of transaction costs, of $0.8 million in “Net gain on sale of undepreciated real estate” on the consolidated statements of operations. Held for Use Impairment For the year ended December 31, 2023, the Company recorded aggregate impairment charges of $103.2 million on three properties within the Company’s Metropolitan Washington, D.C. area in the Company's Other segment. These impairments resulted from the shortened hold period assumptions for the assets as a result of the Company's plan to exit these markets as conditions permit and it was determined that the carrying value exceeded the Company's estimated fair value of the properties. The estimated fair value is considered Level 3 in accordance with ASC 820 and was determined by estimating discounted cash flows using significant unobservable inputs, which were the discount rate of 10.00% and residual capitalization rate of 8.50%. During the year ended December 31, 2023, the Company recognized impairment losses totaling $11.7 million on properties located in the Pennsylvania Suburbs segment. The estimated fair value is considered Level 3 in accordance with ASC 820 and was based upon an executed purchase and sale agreement as of September 30, 2023 that was not completed as of December 31, 2023 due to the termination of the purchase and sale agreement. During the year ended December 31, 2022, the Company recognized an impairment loss totaling approximately $4.7 million on a property located in the Other segment. The Company’s estimated fair value is considered Level 3 in accordance with ASC 820, and was based on a pending offer form a third party to acquire the property and the subsequent execution of a purchase and sale agreement. Held for Sale As of December 31, 2023 and 2022, the Company had no assets held for sale. As of December 31, 2021, the Company determined that the sale of two adjacent parcels of land within the Other segment totaling 10.0 acres was probable and classified these properties as held for sale. As such, $0.6 million was classified as Assets held for sale, net” on the consolidated balance sheets. The Company closed on the sale of the two parcels of land on January 20, 2022 for an aggregate sales price of $1.6 million.

INVESTMENT IN UNCONSOLIDATED RE

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES	12 Months Ended
	Dec. 31, 2023
Equity Method Investments and Joint Ventures [Abstract]
INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES	4. INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES As of December 31, 2023, the Company held ownership interests in twelve unconsolidated real estate ventures for a net aggregate investment balance of $552.5 million, which includes a negative investment balance in one unconsolidated real estate venture of $48.7 million, reflected within “Other liabilities” on the consolidated balance sheets. As of December 31, 2023, five of the real estate ventures owned properties that contained an aggregate of approximately 9.1 million net rentable square feet of office space; two real estate ventures owned 1.4 acres of land held for development; four real estate venture owned 7.5 acres of land in active development; and one real estate venture owned a mixed used tower comprised of 250 apartment units and 0.2 million net rentable square feet of office/retail space. The Company accounts for its interests in the unconsolidated real estate ventures, which range from 15% to 78%, using the equity method. Certain of the unconsolidated real estate ventures are subject to specified priority allocations of distributable cash. The Company earned management fees from the unconsolidated real estate ventures of $8.1 million, $8.2 million and $8.1 million for the years ended December 31, 2023, 2022 and 2021, respectively. The Company earned leasing commissions from the unconsolidated real estate ventures of $3.8 million, $2.5 million and $3.8 million for the years ended December 31, 2023, 2022 and 2021, respectively. The Company had outstanding accounts receivable balances from the unconsolidated real estate ventures of $3.5 million and $2.9 million as of December 31, 2023 and 2022, respectively. The amounts reflected in the following tables (except for the Company’s share of equity in income) are based on the financial information of the individual unconsolidated real estate ventures. The Company records operating losses of a real estate venture in excess of its investment balance if the Company is liable for the obligations of the real estate venture or is otherwise committed to provide financial support to the real estate venture. The Company’s investment in the unconsolidated real estate ventures as of December 31, 2023 and 2022, and the Company’s share of the unconsolidated real estate ventures’ income (loss) for the years ended December 31, 2023, 2022, and 2021 was as follows (in thousands): Ownership Percentage Carrying Amount Company's unconsolidated real estate venture Income (Loss) Unconsolidated Real Estate Venture Debt at 100%, gross 2023 2022 2023 2022 2021 2023 2022 Office Properties Commerce Square Venture 78% (a) $ 272,216 $ 238,105 $ (18,791) $ (12,128) $ (15,501) $ 220,000 $ 206,737 Mid-Atlantic Office Venture (e) 40% (a) — 31,005 (26,448) 412 932 132,770 128,904 Herndon Innovation Center Metro Portfolio Venture, LLC 15% 3,518 15,304 (11,854) (536) (174) 233,443 207,302 MAP Venture (b) 50% (48,733) (35,411) (10,580) (8,340) (8,683) 179,842 182,053 Cira Square 20% 25,242 27,815 (2,474) (985) — 257,700 257,700 Other 4040 Wilson Venture (c) 50% 29,419 29,633 (2,536) (1,211) (2,258) 145,000 145,070 1919 Venture (d) 50% — — — 1,392 427 — — Brandywine - AI Venture LLC 50% — — — — (721) — — Development Properties 3025 JFK Venture (c) 58% 62,034 57,630 (4,456) (35) (118) 152,032 60,118 JBG - 51 N Street (c) 70% 21,150 21,208 (435) (382) (402) — — JBG - 1250 First Street Office (c) 70% 17,843 17,759 (269) (195) (199) — — 3151 Market Street Venture (c) 64% 90,645 63,751 (72) (8) — — — One Uptown - Office (c) 57% 47,036 34,980 — — — 51,701 16,895 One Uptown - Multifamily (c) 50% 32,124 30,445 — — — 40,270 — $ 552,494 $ 532,224 $ (77,915) $ (22,016) $ (26,697) $ 1,412,758 $ 1,204,779 (a) Ownership percentage represents the Company’s combined interest including preferred and common equity holdings. See “Commerce Square Venture” and “Mid-Atlantic Office JV” sections below for more information. (b) Included within “Other Liabilities” on the consolidated balance sheet. (c) This entity is a VIE. (d) On November 30, 2022, the Company sold its interest in 1919 Venture. See “1919 Venture” sections for more information on the disposal. (e) On January 9, 2024 the real estate venture’s secured mortgage loan matured. The real estate venture is in active discussions, including with the mortgage lender, as to a potential extension of the loan or other restructuring of the venture. The following is a summary of the financial position of the unconsolidated real estate ventures in which the Company held interests as of December 31, 2023 and December 31, 2022 (in thousands): December 31, 2023 December 31, 2022 Net property $ 2,339,921 $ 2,117,226 Other assets 534,658 506,213 Other liabilities 443,536 446,101 Debt, net 1,407,858 1,198,213 Equity (a) 1,023,185 979,125 (a) This amount does not include the effect of the basis difference between the Company's historical cost basis and the basis recorded at the real estate venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from the impairment of investments, purchases of third party interests in existing real estate ventures and upon the transfer of assets that were previously owned by the Company into a real estate venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the real estate venture level. The following is a summary of results of operations of the unconsolidated real estate ventures in which the Company held interests during the twelve-month periods ended December 31, 2023, 2022 and 2021 (in thousands): Year Ended December 31, 2023 2022 2021 Revenue $ 232,895 $ 244,981 $ 214,792 Operating expenses (122,181) (124,608) (117,273) Interest expense, net (78,909) (49,007) (30,569) Depreciation and amortization (100,205) (103,378) (97,147) Provision for impairment — — (1,393) Net loss $ (68,400) $ (32,012) $ (31,590) Ownership interest % Various Various Various Company's share of net loss $ (39,637) $ (21,594) $ (25,972) Other-than-temporary impairment (a) (37,176) — — Basis adjustments and other (1,102) (422) (725) Equity in loss of unconsolidated real estate ventures $ (77,915) $ (22,016) $ (26,697) (a) Represents other-than-temporary impairment on investment in unconsolidated joint venture due to a decline in fair value below the carrying value of our investments in the unconsolidated joint venture for the year ended December 31, 2023. As of December 31, 2023, the aggregate principal payments of the unconsolidated real estate ventures recourse and non-recourse debt payable to third-parties are as follows (in thousands): 2024 $ 803,756 2025 152,032 2026 236,971 2027 — 2028 220,000 Thereafter — Total principal payments 1,412,759 Net deferred financing costs (4,901) Outstanding indebtedness $ 1,407,858 One Uptown Ventures On December 1, 2021, the Company established the One Uptown Ventures with affiliates of Canyon Partners Real Estate to commence development of One Uptown, a $335.6 million mixed-use project in Austin, Texas. One Uptown has been designed to deliver 348,000 square feet of Class-A workspace and 15,000 square feet of street-level retail space (through the “ office ” joint venture) and 341 apartment residences and a public park (through the “ multifamily ” joint venture) and a six-story parking garage to be shared by the two joint ventures. The Company's partner in each of the two joint ventures has agreed, subject to customary funding conditions, including closing of the applicable construction loan, to fund approximately $64.5 million of the combined project costs in exchange for a 50% preferred equity interest in each of the two joint ventures, with the Company retaining a 50% common equity interest in each. Under the terms of each of the joint venture agreements, the joint venture partner had no obligation to fund any portion of the applicable project costs until the closing of the applicable construction loan. The absence of this obligation prevented Company from meeting the sale recognition criteria of ASC 606 until the applicable closings of the construction loans. On July 29, 2022, the One Uptown Ventures closed on two separate construction loans. The office joint venture closed on a $121.7 million construction loan which bears interest at Secured Overnight Offering Rate ( “ SOFR ”) plus 3.00% and the multifamily joint venture closed on an $85.0 million construction loan which bears interest at SOFR plus 2.45%, plus, in each case, a daily SOFR adjustment of 10 basis points. Both loans mature in July 2026. The Company has also provided a carry guarantee and limited payment guarantee up to 30% and 15% of the principal balance of the $121.7 million and $85 million construction loan, respectively. The Company subsequently recognized the formation of the joint ventures and deconsolidated the projects upon the closing of the loans. The Company has determined that the each of the One Uptown Ventures is a VIE. As a result, the Company used the VIE model under the accounting standard for consolidation in order to determine whether to consolidate the One Uptown Ventures. Based upon each member's shared power over the activities of the One Uptown Ventures under the operating and related agreements, and the Company's lack of control over the development and construction phases of the project, the One Uptown Ventures are accounted for under the equity method of accounting. During the twelve months ended December 31, 2023, the Company contributed $10.8 million to the One Uptown - Office Venture, increasing the Company's aggregate investment balance to $47.0 million at December 31, 2023 and increasing the Company's equity ownership from 50% to 57%. The contribution was used to pay interest on the One Uptown - Office Venture construction loan and arose from higher than budgeted interest carry costs. 3151 Market Street Venture On July 14, 2022, the Company formed a joint venture, with an unaffiliated third party, to develop a life science/office building containing approximately 417,000 rentable square feet under a long-term ground lease located at 3151 Market Street in Philadelphia, Pennsylvania. The estimated project cost is approximately $317 million, and the joint venture partner has agreed, subject to customary funding conditions, to fund up to approximately $49.9 million of the project costs in exchange for a 35% preferred equity interest in the venture. The Company has determined that the 3151 Market Street Venture is VIE. As a result, the Company used the VIE model under the accounting standard for consolidation in order to determine whether to consolidate the 3151 Market Street Venture. Based upon each member's shared power over the activities of the 3151 Market Street Venture under the operating and related agreements, and the Company's lack of control over the development and construction phases of the project, 3151 Market Street Venture is accounted for under the equity method of accounting. During the twelve months ended December 31, 2023, the Company contributed $15.4 million to the 3151 Market Street Venture, increasing the Company's aggregate investment balance to $90.6 million at December 31, 2023 and increasing the Company's equity ownership from 58% to 64%. The contribution was used to pay interest on the 3151 Market Street Venture construction loan and arose from higher than budgeted interest carry costs. Cira Square On March 17, 2022, the Company formed a joint venture, Cira Square REIT, LLC (“Cira Square Venture”), for the purpose of acquiring Cira Square, an office property located at 2970 Market Street in Philadelphia, Pennsylvania containing 862,692 rentable square feet for a gross purchase price of $383.0 million. The Company owns a 20% common equity interest in Cira Square Venture and provided an initial capital contribution of $28.6 million on the closing date. On the closing date, Cira Square Venture obtained $257.7 million of third-party debt financing secured by the property. The loan bears interest at 3.50% over one-month term SOFR per annum capped at a total maximum interest rate of 6.75% per annum, and matures in March 2024. Based on the facts and circumstances at the formation of Cira Square Venture, the Company determined that the venture is not a VIE in accordance with the accounting standard for the consolidation of VIEs. As a result, the Company used the voting interest model under the accounting standard for consolidation in order to determine whether to consolidate Cira Square Venture. Based upon each member's substantive participating rights over the activities of Cira Square Venture under the operating and related agreements, it is not consolidated by the Company, and is accounted for under the equity method of accounting. 4040 Wilson Venture The 4040 Wilson LLC Venture (“4040 Wilson”) consists of one property containing an aggregate of 225,000 square feet of office/retail and 250 apartment units, located in the Metropolitan Washington, D.C. segment. The Company and its partner each own a 50% interest in 4040 Wilson. The residential component and office/retail portion of 4040 Wilson were substantially complete and placed into service during the first quarter of 2020 and the first quarter of 2021, respectively. During the fourth quarter of 2021, 4040 Wilson refinanced the $150.0 million secured construction loan into a $155.0 million mortgage loan secured by the property. The interest rate on this loan is 1.8% over term SOFR and matures in December 2026. Effective January 3, 2023, this debt was swapped to a fixed rate of 5.71% through the maturity of the loan. Brandywine - AI Venture During the year ended December 31, 2021, Brandywine - AI Venture, recorded a $1.4 million held for sale impairment charge related to 3141 Fairview Park Drive. The Company’s share of the impairment charge was $0.7 million, which is reflected in “Equity in loss of Real Estate Ventures” in the consolidated statements of operations for the year ended December 31, 2021. The impairment was measured based on an executed sale agreement with a third-party. The Company determined that its investment in the real estate venture is not impaired as the Company's share of the distributable cash is in excess of the Company's basis in the real estate venture. On November 9, 2021, BDN AI Venture sold 3141 Fairview Park Drive, the last remaining office property, totaling 183,618 rentable square feet in Falls Church, Virginia, at an aggregate sales price of $27.6 million. The Company received cash proceeds of $12.6 million after closing costs. The Company recorded an $3.0 million gain within the caption “Net gain on real estate venture transactions” within its consolidated statements of operations for the year ended December 31, 2021 upon liquidation of the venture. 3025 JFK Venture On February 2, 2021, the Company contributed its investment in a 99-year prepaid leasehold interest in a one-acre land parcel held for development at 3025 JFK Boulevard in Philadelphia, Pennsylvania to the 3025 JFK Venture. The Company's initial investment in this real estate venture at February 2, 2021 was $34.8 million. The real estate venture was formed to develop a 570,000 square foot mixed-use building at property under the long-term ground lease. The estimated project cost is approximately $287.3 million, and the joint venture partner agreed, subject to customary funding conditions, to fund up to approximately $45.2 million of the project costs in exchange for a 45% preferred equity interest in the venture and the Company will retain a 55% preferred equity interest. On July 23, 2021, the 3025 JFK Venture closed on a $186.7 million construction loan, which bears interest at 3.50% plus LIBOR (subject to a LIBOR floor of 0.25%) per annum and matures in July 2025. In addition to its $34.8 million credit for contribution of the leasehold interest at 3025 JFK Venture, the Company has funded $20.5 million of project costs as of December 31, 2022. The remaining project costs will be funded by the joint venture partner and the construction loan. During the twelve months ended December 31, 2023, the Company contributed $7.1 million to the 3025 JFK Venture increasing Company's equity ownership from 55% to 58%. Utilizing the proceeds from the contribution, the 3025 JFK Venture entered into an interest rate cap agreement to help mitigate the interest rate volatility associated with the variable interest rate on the 3025 JFK Venture's construction loan, which is scheduled to mature in July 2025. The interest rate cap has an initial notional value of $148.0 million which has accreted up to $187.0 million following the projected draw schedule. The strike rate of the interest rate cap is 3.00% and the stated interest rate of the construction loan is SOFR + 3.6%. With the interest rate cap in-place, the maximum interest rate due by the 3025 JFK Venture is 6.60%. The Company has determined that the 3025 JFK Venture is a VIE. As a result, the Company used the VIE model under the accounting standard for consolidation in order to determine whether to consolidate the 3025 JFK Venture. Based upon each member’s shared power over the activities of 3025 JFK Venture under the operating and related agreements, and the Company’s lack of control over the development and construction phases of the project, 3025 JFK Venture is accounted for under the equity method of accounting. Mid-Atlantic Office JV On December 21, 2020, the Company contributed a portfolio of twelve properties containing an aggregate of 1,128,645 square feet, nine of which are located in the Pennsylvania suburbs segment and three located in the Company's former Metropolitan Washington, D.C. segment, to the Mid-Atlantic Office JV, for a gross sales price of $192.9 million. After the transaction, the Company owns approximately 25% of the equity interest in the Mid-Atlantic Office JV through a $20.0 million preferred equity holding and approximately 15% of the equity interest through a common equity interest (representing 20% of the total common equity), for a combined approximately 40% equity interest in the venture. On the closing date, Mid-Atlantic Office JV also obtained $147.4 million of third-party debt financing secured by the twelve properties within the venture, with an initial advance of $120.8 million. The remaining funds available under the loan are $18.5 million. The loan bears interest at LIBOR + 3.15% capped at a total maximum interest rate of 5.7% and matured on January 9, 2024. The real estate venture is in discussions, including with the mortgage lender as to a potential extension of the loan or other restructuring of the venture. As of December 31, 2023, our investment in the Mid-Atlantic Office JV was zero, and we have discontinued applying the equity method of accounting on these assets as we have not guaranteed their obligations or otherwise committed to providing financial support. Commerce Square Venture The properties held by the venture are encumbered by existing mortgages that were set to expire on April 5, 2023. The lender of the mortgages provided the venture with a two month extension until June 5, 2023. On June 2, 2023, the mortgages were refinanced through a secured loan facility. The secured loan totals $220.0 million and bears an all-in fixed interest rate of 7.79% which matures in June 2028. In connection with the refinancing, the Company contributed $46.5 million to the Commerce Square Venture in exchange for an additional 8% equity interest in the venture. Herndon Innovation Center Metro Portfolio Venture, LLC The Herndon Innovation Center Metro Portfolio Venture, LLC (“Herndon Innovation Center”) consists of eight properties containing an aggregate of 1,293,197 square feet, located in the Company's former Metropolitan Washington, D.C. segment. The Company and its partner own 15% and 85% interests in the Herndon Innovation Center, respectively. The properties held by the venture are encumbered by a $233.4 million secured mortgage loan that is scheduled to mature in March 2024 and is nonrecourse to the Company. The Company and its partners are in active discussions, including with the mortgage lender, as to a potential extension of the loan or other restructuring on the venture. At present, there can be no assurance as to the outcome of these discussions. MAP Venture The MAP Venture owns 58 office properties that contain an aggregate of 3,924,783 square feet located in the Pennsylvania Suburbs, New Jersey/Delaware, Metropolitan Washington, D.C. and Richmond, Virginia (“MAP Venture”). The MAP Venture leases the land parcels under the 58 office properties through a ground lease that extends through February 2115. Annual payments by the MAP Venture, as tenant under the ground lease, initially total $11.9 million and increase 2.5% annually through November 2025. Thereafter, annual rental payments increase by 2.5% or CPI at the discretion of the lessor. The mortgage loan had an original maturity date of August 1, 2023. The lender provided the MAP Venture with three successive two-month extensions until February 27, 2024. At December 31, 2023, the mortgage balance was $179.8 million. The Company and its partner are actively working to recapitalize the MAP Venture and the mortgage debt prior to maturity, but there can be no assurances that the debt will be satisfied or additional extension options will be provided by the existing lender. At December 31, 2023, the Company's negative investment balance was $48.7 million. The Company has no obligation to fund additional equity to the MAP Venture. 1919 Venture On November 30, 2022, the Company sold its 50% ownership interest in the 1919 Venture for a gross sales price of $83.2 million, a portion of which satisfied in full the $44.4 million outstanding loan between the Company and the venture. The Company recorded a gain on sale of $26.7 million with the caption “Net gain on real estate venture transactions” within its consolidated statement of operations for the year ended December 31, 2022. JBG Ventures JBG Ventures consists of 51 N 50 Patterson, Holdings, LLC Venture (“51 N Street”) and 1250 First Street Office, LLC Venture (“1250 First Street”), with the Company owning a 70.0% equity interest and JBG/DC Manager, LLC (“JBG”) owning a 30.0% equity interest in each of the two ventures. 51 N Street owns 0.9 acres of undeveloped land and 1250 First Street, owns 0.5 acres of undeveloped land.

DEBT AND PREFERRED EQUITY INVES

DEBT AND PREFERRED EQUITY INVESTMENTS	12 Months Ended
	Dec. 31, 2023
Investments, Debt and Equity Securities [Abstract]
DEBT AND PREFERRED EQUITY INVESTMENTS	5. DEBT AND PREFERRED EQUITY INVESTMENTS Austin Preferred Equity Investment On December 31, 2020, the Company invested $50.0 million in exchange for a preferred equity interest in a single-purpose entity that owned two stabilized office buildings located in Austin, Texas. The Company accounted for this mandatorily redeemable investment as a note receivable, which was included within “Other assets” on the consolidated balance sheets. The preferred equity interest accrued a 9.0% annual return, compounded and paid monthly. The investment was required to be redeemed no later than December 31, 2023 (subject to a one-year extension option). On September 3, 2021, the $50.0 million investment was redeemed prior to maturity. 1919 Venture Note Receivable

LEASES

LEASES	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
LEASES	6. LEASES Lessor Accounting The Company leases properties to tenants under operating leases with various expiration dates. Future contractual lease payments under operating leases at December 31, 2023 are as follows (in thousands): Year 2024 $ 348,890 2025 344,575 2026 329,584 2027 294,997 2028 262,816 Thereafter 944,863 Lessee Accounting As of December 31, 2023, the Company is the lessee under six long-term ground leases classified as “operating leases” in the consolidated balance sheets. Certain of the Company’s ground leases contain extension options and the Company considered all relevant factors in determining if it was reasonably certain that it would exercise such extension options. The Company concluded that it was not reasonably certain that it would exercise the extension options and, therefore, has not included the extension period in the remaining lease terms. With the exception of certain ground leases that are subject to rent increases periodically based on the CPI index, all lease payments under the ground lease are fixed. The table below summarizes the Company’s operating lease cost (in thousands) recognized through “Property operating expenses” on the consolidated statements of operations (in thousands): Year Ended December 31, Lease Cost 2023 2022 Fixed lease cost $ 2,100 $ 2,100 Variable lease cost 57 67 Total $ 2,157 $ 2,167 Weighted-average remaining lease term (years) 54.0 54.6 Weighted-average discount rate 6.3 % 6.3 % Lease payments by the Company under the terms of all noncancellable ground leases of land are expensed on a straight-line basis regardless of when payments are due. The Company’s ground leases, excluding prepaid ground leases, have remaining lease terms ranging from 6 to 61 years. Lease payments on noncancellable leases at December 31, 2023 are as follows (in thousands): Year Minimum Rent 2024 $ 1,305 2025 1,321 2026 1,338 2027 1,355 2028 1,373 Thereafter 105,065 Total lease payments $ 111,757 Less: Imputed interest 88,388 Present value of operating lease liabilities $ 23,369 The Company obtained ground tenancy rights related to three properties in Philadelphia, Pennsylvania, which provide for contingent rent participation by the lessor in certain capital transactions and net operating cash flows of the properties after certain returns are achieved by the Company. Such amounts, if any, will be reflected as contingent rent when incurred. The ground leases also provide for payment by the Company of certain operating costs relating to the land, primarily real estate taxes. The above schedule of future minimum rental payments does not include any contingent rent amounts or any reimbursed expenses.
LEASES	6. LEASES Lessor Accounting The Company leases properties to tenants under operating leases with various expiration dates. Future contractual lease payments under operating leases at December 31, 2023 are as follows (in thousands): Year 2024 $ 348,890 2025 344,575 2026 329,584 2027 294,997 2028 262,816 Thereafter 944,863 Lessee Accounting As of December 31, 2023, the Company is the lessee under six long-term ground leases classified as “operating leases” in the consolidated balance sheets. Certain of the Company’s ground leases contain extension options and the Company considered all relevant factors in determining if it was reasonably certain that it would exercise such extension options. The Company concluded that it was not reasonably certain that it would exercise the extension options and, therefore, has not included the extension period in the remaining lease terms. With the exception of certain ground leases that are subject to rent increases periodically based on the CPI index, all lease payments under the ground lease are fixed. The table below summarizes the Company’s operating lease cost (in thousands) recognized through “Property operating expenses” on the consolidated statements of operations (in thousands): Year Ended December 31, Lease Cost 2023 2022 Fixed lease cost $ 2,100 $ 2,100 Variable lease cost 57 67 Total $ 2,157 $ 2,167 Weighted-average remaining lease term (years) 54.0 54.6 Weighted-average discount rate 6.3 % 6.3 % Lease payments by the Company under the terms of all noncancellable ground leases of land are expensed on a straight-line basis regardless of when payments are due. The Company’s ground leases, excluding prepaid ground leases, have remaining lease terms ranging from 6 to 61 years. Lease payments on noncancellable leases at December 31, 2023 are as follows (in thousands): Year Minimum Rent 2024 $ 1,305 2025 1,321 2026 1,338 2027 1,355 2028 1,373 Thereafter 105,065 Total lease payments $ 111,757 Less: Imputed interest 88,388 Present value of operating lease liabilities $ 23,369 The Company obtained ground tenancy rights related to three properties in Philadelphia, Pennsylvania, which provide for contingent rent participation by the lessor in certain capital transactions and net operating cash flows of the properties after certain returns are achieved by the Company. Such amounts, if any, will be reflected as contingent rent when incurred. The ground leases also provide for payment by the Company of certain operating costs relating to the land, primarily real estate taxes. The above schedule of future minimum rental payments does not include any contingent rent amounts or any reimbursed expenses.

DEFERRED COSTS

DEFERRED COSTS	12 Months Ended
	Dec. 31, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
DEFERRED COSTS	7. DEFERRED COSTS As of December 31, 2023 and 2022, the Company’s deferred costs were comprised of the following (in thousands): December 31, 2023 Total Cost Accumulated Amortization Deferred Costs, net Leasing costs $ 164,274 $ (71,220) $ 93,054 Financing costs - Unsecured Credit Facility 4,688 (1,758) 2,930 Total $ 168,962 $ (72,978) $ 95,984 December 31, 2022 Total Cost Accumulated Amortization Deferred Costs, net Leasing costs $ 155,457 $ (62,920) $ 92,537 Financing costs - Unsecured Credit Facility 4,688 (586) 4,102 Total $ 160,145 $ (63,506) $ 96,639

INTANGIBLE ASSETS AND LIABILITI

INTANGIBLE ASSETS AND LIABILITIES	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS AND LIABILITIES	8. INTANGIBLE ASSETS AND LIABILITIES As of December 31, 2023 and 2022, the Company’s intangible assets/liabilities were comprised of the following (in thousands): December 31, 2023 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 24,281 $ (16,673) $ 7,608 Tenant relationship value 110 (52) 58 Above market leases acquired 75 (47) 28 Total intangible assets, net $ 24,466 $ (16,772) $ 7,694 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 17,588 $ (9,318) $ 8,270 December 31, 2022 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 55,715 $ (37,437) $ 18,278 Tenant relationship value 167 (104) 63 Above market leases acquired 331 (221) 110 Total intangible assets, net $ 56,213 $ (37,762) $ 18,451 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 20,985 $ (10,663) $ 10,322 For the years ended December 31, 2023, 2022, and 2021, the Company accelerated the amortization of intangible assets by approximately $0.1 million, $0.4 million, and $3.6 million, respectively, as a result of tenant move-outs prior to the end of the associated lease term. For the years ended December 31, 2023, 2022, and 2021 the Company accelerated the amortization of approximately $0.01 million, $0.1 million, and $0.6 million of intangible liabilities as a result of tenant move-outs. As of December 31, 2023, the Company’s annual amortization for its intangible assets/liabilities, assuming no prospective early lease terminations, was as follows (dollars in thousands): Assets Liabilities 2024 $ 1,818 $ 929 2025 1,485 869 2026 1,093 739 2027 808 623 2028 313 534 Thereafter 2,177 4,576 Total $ 7,694 $ 8,270

DEBT OBLIGATIONS

DEBT OBLIGATIONS	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
DEBT OBLIGATIONS	9. DEBT OBLIGATIONS The following table sets forth information regarding the Company’s consolidated debt obligations outstanding as of December 31, 2023 and 2022 (in thousands): December 31, 2023 December 31, 2022 Effective Maturity SECURED DEBT $245.0M 5.88% Secured Term Loan due 2028 $ 245,000 $ — 5.88% February 2028 $50.0M Construction Loan due 2026 13,824 — SOFR + 2.50% August 2026 Principal balance outstanding 258,824 — Less: deferred financing costs (3,153) — Total Secured indebtedness $ 255,671 $ — UNSECURED DEBT $600 million Unsecured Credit Facility $ — $ 88,500 SOFR + 1.15% June 2026 (a) Term Loan - Swapped to fixed 250,000 250,000 SOFR + 1.30% June 2027 (b) $70.0 million Term Loan 70,000 — SOFR + 1.85% February 2024 (a)(c) $350.0M 3.95% Guaranteed Notes due 2023 — 54,301 3.87% February 2023 (d) $350.0M 4.10% Guaranteed Notes due 2024 (e) 340,000 350,000 3.78% October 2024 $450.0M 3.95% Guaranteed Notes due 2027 450,000 450,000 4.03% November 2027 $350.0M 7.55% Guaranteed Notes due 2028 350,000 350,000 7.98% (f) March 2028 $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 SOFR + 1.51% (g) March 2035 Indenture IB (Preferred Trust I) 25,774 25,774 SOFR + 1.51% (g) April 2035 Indenture II (Preferred Trust II) 25,774 25,774 SOFR + 1.51% (g) July 2035 Principal balance outstanding 1,888,610 1,971,411 Plus: original issue premium (discount), net 1,878 2,934 Less: deferred financing costs (7,327) (9,307) Total unsecured indebtedness $ 1,883,161 $ 1,965,038 (a) Spread includes a 10 basis point daily SOFR adjustment. (b) On November 23, 2022, the unsecured term loan of $250.0 million was swapped to a fixed rate of 5.01% and matures on June 30, 2027. The effective date of the swap is January 31, 2023. (c) The maturity date of the Unsecured Term Loan is subject to a 12 month optional extension. The Company executed the 12 month extension through February 2025 . (d) On January 20, 2023, the Company redeemed in full its then outstanding 3.95% Guaranteed Notes due 2023 (the “ 2023 Notes ” ). The redemption price of the 2023 Notes was approximately $55.2 (approximately $54.3 million in principal and approximately $0.92 million of accrued and unpaid interest). (e) On December 22, 2023, the Company repurchased $10.0 million of its outstanding $350 million Notes due 2023 ahead of its scheduled maturity at a price of 98.6% and paid accrued interest of $0.1 million. As a result of the repurchase the Company recorded a gain from the early extinguishment of debt of $0.1 million. (f) The note includes an interest rate adjustment provision whereby the interest rate payable on the notes is subject to an 25 basis point adjustment if either Moody's or S&P downgrades (or subsequently upgrades) its rating assigned to the 2028 Notes. During the third quarter of 2023, Moody’s downgraded our senior unsecured credit rating from Baa3 to Ba1. As a result of the downgrade, the interest rate on our 2028 Notes increased 25 basis points in September 2023 to 7.80%. Subsequent to December 31, 2023, S&P downgraded our senior unsecured credit rating from BBB- to BB+. As a result of the downgrade, the interest rate will increase 25 basis points in March 2024 to 8.05%. (g) On January 16, 2024, the Trust Preferred I - Indenture IA was swapped to a fixed rate at 5.14% for the period from March 30, 2024 to December 30, 2026 and Trust Preferred I - Indenture IB and Trust Preferred II - Indenture II were swapped to a fixed rate at 5.24% for the period from January 30, 2024 to January 30, 2027. 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. Secured Facility due 2028 On January 19, 2023, seven indirect wholly-owned subsidiaries of the Company entered into a term loan agreement secured by seven operating properties in the aggregate principal amount of $245.0 million (the “Secured Facility”). The Secured Facility has a scheduled maturity date of February 6, 2028 and may be prepaid in full on or after March 6, 2025, subject to a prepayment premium, and may be prepaid in full on or after August 6, 2027 without any prepayment premium. The Secured Facility bears interest at 5.88% per year through the maturity date and is interest-only (payable monthly) through the maturity date. Unsecured Credit Facility and Unsecured Term Loan On March 1, 2023, the Company entered into an unsecured one-year term loan agreement in the aggregate principal amount of $70.0 million (the “2023 Term Loan”). The 2023 Term Loan was scheduled to mature on February 28, 2024. In January 2024, the Company executed its option to extend for an additional twelve months to February 28, 2025 upon customary terms and conditions. The 2023 Term Loan bears interest at Daily Simple SOFR plus 1.75% with a 0.10% SOFR adjustment per year through the maturity date and is interest-only (payable monthly) through the maturity date. On June 30, 2022, the Company entered into the Second Amended and Restated Credit Agreement (as amended and restated, the “2022 Credit Agreement”). The 2022 Credit Agreement among other things: (i) maintains the total commitment under the line credit of $600.0 million (the “Revolving Credit Facility”) and provides an unsecured term loan in the initial amount of $250.0 million (the “Term Loan”) with a scheduled maturity date of June 30, 2027; (ii) extended the maturity date of the Revolving Credit Facility from July 15, 2022 to June 30, 2026, with two six-month extensions at the Company’s election subject to specified conditions and subject to payment of an extension fee; (iii) reduced the interest rate margins applicable to SOFR revolving loans; and (iv) provides for an additional interest rate option based on a floating SOFR rate. In connection with the amendments, the Company capitalized $4.7 million and $2.0 million in financing costs, related to the Revolving Credit Facility and the Term Loan, respectively. The financing costs will be amortized through the maturity dates for each of the Revolving Credit Facility and the Term Loan. Upon closing of the 2022 Credit Agreement, the Term Loan was funded in full and the proceeds thereof, together with cash on hand, were used to prepay in full the Company’s unsecured term loan (“Term Loan C”) in the principal amount of $250.0 million, together with accrued and unpaid interest thereon. Term Loan C was scheduled to mature on October 8, 2022. Under the 2022 Credit Agreement, the Company may, subject to specified terms and conditions (including receipt of commitments from one or more lenders, whether or not currently parties to the 2022 Credit Agreement), elect to increase the amount of the Revolving Credit Facility and/or Term Loan or request one or more new pari passu tranches of unsecured term loans (each, an “Incremental Facility”), provided that the aggregate amount of all such increases is limited to $500.0 million. Up to $50.0 million of borrowing availability under the 2022 Credit Agreement is available for the issuance of letter of credits. Borrowings under the Revolving Credit Facility bear interest at a rate equal to either (i) the SOFR rate plus a margin of 72.5 to 140 basis points, or (ii) a base rate plus a margin of 0 to 40 basis points: and the Term Loan and borrowings under an Incremental Facility bear interest at a rate equal to either (i) the SOFR rate plus a margin of 80 to 160 basis points, or (ii) a base rate plus a margin of 0 to 60 basis points. The applicable margin will be determined based upon the unsecured senior debt rating of the Operating Partnership or the absence of such a rating. The Company also pays a quarterly facility fee on the total commitments under the Revolving Credit Facility. The terms of the 2022 Credit Agreement require that the Company maintain customary financial and other covenants, including: (i) a fixed charge coverage ratio greater than or equal to 1.5 to 1.00; (ii) a leverage ratio less than or equal to 0.60 to 1.00, subject to specified exceptions; (iii) a ratio of unsecured indebtedness to unencumbered asset value less than or equal to 0.60 to 1.00, subject to specified exceptions; (iv) a ratio of secured indebtedness to total asset value less than or equal to 0.40 to 1.00; and (v) a ratio of unencumbered cash flow to interest expense on unsecured debt greater than 1.75 to 1.00. In addition, the 2022 Credit Agreement restricts payments of dividends and distributions on shares in excess of 95% of the Company's funds from operations (FFO) except to the extent necessary to enable the Company to continue to qualify as a REIT for federal income tax purposes. The Company had no outstanding borrowings under the Revolving Credit Facility as of December 31, 2023. During the twelve months ended December 31, 2023, the weighted-average interest rate on Revolving Credit Facility borrowings was 5.94% resulting in $0.6 million of interest expense. During the twelve months ended December 31, 2022 weighted-average interest rate on Revolving Credit Facility borrowings was 3.04% resulting in $5.6 million of interest expense. Secured Construction Loan due 2026 On August 15, 2023, the Company entered into a construction loan agreement secured by the development project at 155 King of Prussia Road in Radnor, Pennsylvania in the aggregate principal amount of $50.0 million (the “Construction Loan”). The Construction Loan has a scheduled maturity date of August 16, 2026 with an option to prepay at any time without a fee, premium or penalty. The Construction Loan bears interest at SOFR plus 2.5%. In connection with the Construction Loan, the Company has provided a completion guaranty, carry guaranty, and limited payment guarantee up to 20% of the loan commitment, as well as customary environmental indemnities and guaranty of customary exceptions to non-recourse provisions in the loan documents. Guaranteed Notes due 2028 On December 13, 2022, the Company completed an underwritten offering of $350.0 million aggregate principal amount of its 7.55% Guaranteed Notes due 2028 (the “2028 Notes”). The 2028 Notes were priced at 99.06% of their face amount and have been reflected net of a discount of approximately $3.3 million in the consolidated balance sheet as of December 31, 2022. The Company received approximately $344.6 million of proceeds after the deduction for underwriting discounts and offering expenses. Guaranteed Notes due 2023 On December 20, 2022, the Company used a portion of the net proceeds from the offering of the 2028 Notes to repurchase $295.7 million aggregate principal amount of its outstanding 3.95% guaranteed notes due 2023 (the “2023 Notes”), through a tender offer, together with $4.1 million of accrued and unpaid interest thereon. The Company recognized a $0.4 million loss on early extinguishment of debt related to the total repurchase. On January 20, 2023, the Company completed the redemption of the remaining $54.3 million aggregate principal amount of the 2023 Notes. The Company was in compliance with all financial covenants as of December 31, 2023. Certain of the covenants restrict the Company’s ability to obtain alternative sources of capital. As of December 31, 2023, the aggregate scheduled principal payments on the Company's debt obligations were as follows (in thousands): 2024 $ 340,000 2025 70,000 2026 13,824 2027 700,000 2028 595,000 Thereafter 428,610 Total principal payments 2,147,434 Net unamortized premiums/(discounts) 1,878 Net deferred financing costs (10,480) Outstanding indebtedness $ 2,138,832

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	10. FAIR VALUE OF FINANCIAL INSTRUMENTS The Company determined the fair values disclosed below using available market information and discounted cash flow analyses as of December 31, 2023 and 2022, 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 December 31, 2023 and 2022 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): December 31, 2023 December 31, 2022 Carrying Amount (a) Fair Value Carrying Amount (a) Fair Value Unsecured notes payable $ 1,486,052 $ 1,386,621 $ 1,549,760 $ 1,411,351 Variable rate debt $ 410,932 $ 370,665 $ 415,278 $ 386,988 Secured fix rate debt $ 241,847 $ 233,088 $ — $ — (a) Net of deferred financing costs of $5.8 million and $7.5 million for unsecured notes payable, $1.5 million and $1.8 million for variable rate debt and $3.2 million and $0.0 million for secured fix rate debt as of December 31, 2023 and December 31, 2022, respectively The Company used quoted market prices as of December 31, 2023 and December 31, 2022 to value the unsecured notes payable and, as such, categorized them as Level 2. The inputs utilized to determine the fair value of the Company’s variable rate debt are categorized as Level 3. The fair value of the variable rate debt was determined using a discounted cash flow model that considered borrowing rates available to the Company for loans with similar terms and characteristics. 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 December 31, 2023 and December 31, 2022. 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 December 31, 2023. Current estimates of fair value may differ from the amounts presented herein.

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	11. DERIVATIVE FINANCIAL INSTRUMENTS Use of Derivative Financial Instruments The Company’s use of derivative instruments is limited to the utilization of interest rate agreements or other instruments to manage interest rate risk exposures and not for speculative purposes. The principal objective of such arrangements is to minimize the risks and/or costs associated with the Company’s operating and financial structure, as well as to hedge specific transactions. The counterparties to these arrangements are major financial institutions with which the Company and its affiliates may also have other financial relationships. The Company is potentially exposed to credit loss in the event of non-performance by these counterparties. However, because of the high credit ratings of the counterparties, the Company does not anticipate that any of the counterparties will fail to meet these obligations as they come due. The Company does not hedge credit or property value market risks through derivative financial instruments. The Company formally assesses, both at the inception of a hedge and on an on-going basis, whether each derivative is highly-effective in offsetting changes in cash flows of the hedged item. If management determines that a derivative is not highly-effective as a hedge or if a derivative ceases to be a highly-effective hedge, the Company will discontinue hedge accounting prospectively for either the entire hedge or the portion of the hedge that is determined to be ineffective. The related ineffectiveness would be charged to the consolidated statement of operations. The valuation of these instruments is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves and implied volatilities. The fair values of interest rate swaps are determined using the market standard methodology of netting the discounted future fixed cash receipts (or payments) and the discounted expected variable cash payments (or receipts). The variable cash payments (or receipts) are based on an expectation of future interest rates (forward curves) derived from observable market interest rate curves. To comply with the provisions of the accounting standard for fair value measurements and disclosures, the Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees. The following table summarizes the terms and fair values of the Company’s derivative financial instruments as of December 31, 2023 and December 31, 2022. 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 12/31/2023 12/31/2022 12/31/2023 12/31/2022 Assets Swap Interest Rate Cash Flow (a) $ 250,000 $ — 3.729 % November 23, 2022 June 30, 2027 $ — $ 255 Liabilities Swap Interest Rate Cash Flow (a) $ — $ 250,000 3.729 % November 23, 2022 June 30, 2027 $ (757) $ — $ 250,000 $ 250,000 (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. Concentration of Credit Risk Concentrations of credit risk arise for the Company when multiple tenants of the Company are engaged in similar business activities, or are located in the same geographic region, or have similar economic features that impact in a similar manner their ability to meet contractual obligations, including those to the Company. The Company regularly monitors its tenant base to assess potential concentrations of credit risk. Management believes the current credit risk portfolio is reasonably well diversified and does not contain an unusual concentration of credit risk. No tenant accounted for 10% or more of the Company’s rents during 2023, 2022 and 2021.

LIMITED PARTNERS' NONCONTROLLIN

LIMITED PARTNERS' NONCONTROLLING INTERESTS IN THE PARENT COMPANY	12 Months Ended
	Dec. 31, 2023
Noncontrolling Interest [Abstract]
LIMITED PARTNERS' NONCONTROLLING INTERESTS IN THE PARENT COMPANY	12. 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 $4.1 million and $4.9 million as of December 31, 2023 and December 31, 2022, respectively. Under the applicable accounting guidance, the redemption value of limited partnership units are carried at fair value. The Parent Company believes that the aggregate settlement value of these interests (based on the number of units outstanding and the average closing price of the common shares during the last five business days of the quarter) was approximately $2.8 million and $3.2 million as of December 31, 2023 and December 31, 2022, respectively.

BENEFICIARIES' EQUITY OF THE PA

BENEFICIARIES' EQUITY OF THE PARENT COMPANY	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
BENEFICIARIES' EQUITY OF THE PARENT COMPANY	13. 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): Year Ended December 31, 2023 2022 2021 Basic Diluted Basic Diluted Basic Diluted Numerator Net income (loss) $ (197,403) $ (197,403) $ 53,992 $ 53,992 $ 12,366 $ 12,366 Net (income) loss attributable to noncontrolling interests 614 614 (168) (168) (77) (77) Nonforfeitable dividends allocated to unvested restricted shareholders (567) (567) (456) (456) (421) (421) Net income (loss) attributable to common shareholders $ (197,356) $ (197,356) $ 53,368 $ 53,368 $ 11,868 $ 11,868 Denominator Weighted-average shares outstanding 171,959,210 171,959,210 171,491,369 171,491,369 170,878,185 170,878,185 Contingent securities/Share-based compensation — — — 834,277 — 1,395,055 Weighted-average shares outstanding 171,959,210 171,959,210 171,491,369 172,325,646 170,878,185 172,273,240 Earnings (loss) per Common Share: Net income (loss) attributable to common shareholders $ (1.15) $ (1.15) $ 0.31 $ 0.31 $ 0.07 $ 0.07 The contingent securities/share-based compensation impact is calculated using the treasury stock method and relates to employee awards settled in shares of the Parent Company. The effect of these securities is anti-dilutive for periods that the Parent Company incurs a net loss from continuing operations available to common shareholders and therefore is excluded from the dilutive earnings per share calculation in such periods. Redeemable common limited partnership units totaling 515,595 at December 31, 2023, 516,467 at December 31, 2022 and 823,983 at December 31, 2021, respectively, 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 years ended December 31, 2023, 2022 and 2021, 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 and Preferred Shares On December 5, 2023, the Parent Company declared a distribution of $0.15 per common share, totaling $26.0 million, which was paid on January 18, 2024 to shareholders of record as of January 4, 2024. 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 years ended December 31, 2023 and 2022, no common shares were repurchased by the Company. Of the 20,000,000 preferred shares authorized, none were outstanding as of December 31, 2023 or December 31, 2022. Common Share Repurchases 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

PARTNERS' EQUITY OF THE PARENT

PARTNERS' EQUITY OF THE PARENT COMPANY	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
PARTNERS' EQUITY OF THE PARENT COMPANY	14. 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): Year Ended December 31, 2023 2022 2021 Basic Diluted Basic Diluted Basic Diluted Numerator Net income (loss) $ (197,403) $ (197,403) $ 53,992 $ 53,992 $ 12,366 $ 12,366 Net loss attributable to noncontrolling interests 22 22 2 2 3 3 Nonforfeitable dividends allocated to unvested restricted unitholders (567) (567) (456) (456) (421) (421) Net income (loss) attributable to common unitholders $ (197,948) $ (197,948) $ 53,538 $ 53,538 $ 11,948 $ 11,948 Denominator Weighted-average units outstanding 172,475,645 172,475,645 172,036,481 172,036,481 171,770,843 171,770,843 Contingent securities/Share-based compensation — — — 834,277 — 1,395,055 Total weighted-average units outstanding 172,475,645 172,475,645 172,036,481 172,870,758 171,770,843 173,165,898 Earnings (loss) per Common Partnership Unit: Net income (loss) attributable to common unitholders $ (1.15) $ (1.15) $ 0.31 $ 0.31 $ 0.07 $ 0.07 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 unit. For the years ended December 31, 2023, 2022 and 2021, 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 and Preferred Mirror Units The Operating Partnership issues partnership units to the Parent Company in exchange for the contribution of the net proceeds of any equity security issuance by the Parent Company. The number and terms of such partnership units correspond to the number and terms of the related equity securities issued by the Parent Company. In addition, the Operating Partnership may also issue separate classes of partnership units. Historically, the Operating Partnership has had the following types of partnership units outstanding: (i) Preferred Partnership Units which have been issued to parties other than the Parent Company; (ii) Preferred Mirror Partnership Units which have been issued to the Parent Company; and (iii) Common Partnership Units which include both interests held by the Parent Company and those held by other limited partners. Preferred Mirror Partnership Units In exchange for the proceeds received in corresponding offerings by the Parent Company of preferred shares of beneficial interest, the Operating Partnership has issued to the Parent Company a corresponding amount of Preferred Mirror Partnership Units with terms consistent with that of the preferred securities issued by the Parent Company. No preferred units were outstanding as of December 31, 2023 or December 31, 2022. Common Partnership Units (Redeemable and General) The Operating Partnership has two classes of Common Partnership Units outstanding as of December 31, 2023: (i) Class A Limited Partnership Interest which are held by both the Parent Company and outside third parties and (ii) General Partnership Interests which are held solely by the Parent Company (collectively, the Class A Limited Partnership Interest, and General Partnership Interests are referred to as “Common Partnership Units”). The holders of the Common Partnership Units are entitled to share in cash distributions from, and in profits and losses of, the Operating Partnership, in proportion to their respective percentage interests, subject to preferential distributions on the preferred mirror units and the preferred units. The Common Partnership Units held by the Parent Company (comprised of both General Partnership Units and Class A Limited Partnership Units) are presented as partner’s equity in the consolidated financial statements. Class A Limited Partnership Interest held by parties other than the Parent Company are redeemable at the option of the holder for a like number of common shares of the Parent Company, or cash, or a combination thereof, at the election of the Parent Company. Because the form of settlement of these redemption rights are not within the control of the Operating Partnership, these Common Partnership Units have been excluded from partner’s equity and are presented as redeemable limited partnership units measured at the potential cash redemption value as of the end of the periods presented based on the closing market price of the Parent Company’s common shares at December 31, 2023, 2022 and 2021, which was $5.40, $6.15 and $13.42, respectively. Class A Units of 515,595 as of December 31, 2023, 516,467 as of December 31, 2022, and 823,983 as of December 31, 2021, respectively, were outstanding and owned by outside limited partners of the Operating Partnership. On December 5, 2023, the Operating Partnership declared a distribution of $0.15 per common partnership unit, totaling $26.0 million, which was paid on January 18, 2024 to unitholders of record as of January 4, 2024. Common Unit Repurchases 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 years ended December 31, 2023 and 2022, the Company did not repurchase any units.

SHARE-BASED COMPENSATION, 401(K

SHARE-BASED COMPENSATION, 401(K) PLAN AND DEFERRED COMPENSATION	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
SHARE-BASED COMPENSATION, 401(K) PLAN AND DEFERRED COMPENSATION	15. SHARE-BASED COMPENSATION, 401(K) PLAN AND DEFERRED COMPENSATION 401(k) Plan The Company sponsors a 401(k) defined contribution plan for its employees. Each employee may contribute up to 100% of annual compensation, subject to specific limitations under the Internal Revenue Code. At its discretion, the Company can make matching contributions equal to a percentage of the employee’s elective contribution and profit sharing contributions. The Company funds its 401(k) contributions annually and plan participants must be employed as of December 31 in order to receive employer contributions, except for employees eligible for qualifying retirement, as defined under the Internal Revenue Code. The Company contributions were $0.7 million, $0.4 million, and $0.5 million in 2023, 2022, and 2021, respectively. Restricted Share Rights Awards As of December 31, 2023, 889,166 restricted share rights (“Restricted Share Rights”) were outstanding under the Company's long term equity incentive plan. These Restricted Share Rights vest over one The following table summarizes the Company’s Restricted Share Rights activity during the year-ended December 31, 2023: Shares Weighted Average Grant Date Fair Value Non-vested at January 1, 2023 553,893 $ 13.22 Granted 808,283 $ 6.03 Vested (458,111) $ 9.29 Forfeited (14,899) $ 8.61 Non-vested at December 31, 2023 889,166 $ 8.79 On February 16, 2023, the Compensation Committee awarded to officers of the Company an aggregate of 528,590 Restricted Share Rights, which vest over three years from the grant date. Each Restricted Share Right entitles the holder to one common share upon settlement. The Parent Company pays dividend equivalents on the Restricted Share Rights prior to the settlement date. Vesting and/or settlement would accelerate if the recipient of the award were to die, become disabled or, in the case of certain of such Restricted Share Rights, retire in a qualifying retirement prior to the vesting or settlement date. Qualifying retirement generally means the recipient’s voluntary termination of employment after reaching at least age 57 and accumulating at least 15 years of service with the Company. In addition, vesting would also accelerate if the Parent Company were to undergo a change of control and, on or before the first anniversary of the change of control, the recipient’s employment were to cease due to a termination without cause or resignation with good reason. The Restricted Share Rights granted in 2023, 2022, and 2021 to certain senior executives include an “outperformance feature” whereby additional shares may be earned, up to 225% of the shares subject to the basic award, based on the Company’s achievement of earnings-based targets and development, or investment, based targets during a three-year performance period with an additional 366 days of service generally required to fully vest. In addition to the basic award, up to an aggregate of 925,642, 406,179, and 388,840 shares may be awarded under the outperformance feature for the 2023, 2022, and 2021 awards, respectively, to those senior officers whose Restricted Share Rights awards include the “outperformance feature.” As of December 31, 2023, the Company has not recognized any compensation expense related to the outperformance features for the 2021 awards and 2022 awards and has recognized $0.5 million related to the outperformance feature for the 2023 awards. The Company will continue to evaluate progression towards achievement of the performance metrics on a quarterly basis and recognize compensation expense for the outperformance feature of these awards should it be determined that achievement of these metrics is probable. In accordance with the accounting standard for share-based compensation, the Company amortizes share-based compensation costs through the qualifying retirement dates for those grantees who meet the conditions for qualifying retirement during the scheduled vesting period and whose award agreements provide for vesting upon a qualifying retirement. In addition, on February 16, 2023, the Compensation Committee awarded non-officer employees an aggregate of 92,703 Restricted Share Rights that generally vest in three equal annual installments. Vesting of these awards is subject to acceleration upon death, disability or termination without cause within one year following a change of control. Restricted Performance Share Units Plan The Compensation Committee has granted performance share-based awards (referred to as Restricted Performance Share Units, or RPSUs) to officers of the Parent Company. The RPSUs are settled in common shares, with the number of common shares issuable in settlement determined based on the Company’s total shareholder return over specified measurement periods compared to total shareholder returns of comparative groups over the measurement periods. The table below presents certain information as to unvested RPSU awards. RPSU Grant Date 3/5/2021 3/3/2022 2/16/2023 Total (Amounts below in shares, unless otherwise noted) Non-vested at January 1, 2023 371,239 513,038 — 884,277 Granted — — 1,057,173 1,057,173 Units Cancelled — — — — Non-vested at December 31, 2023 371,239 513,038 1,057,173 1,941,450 Measurement Period Commencement Date 1/1/2021 1/1/2022 1/1/2023 Measurement Period End Date 12/31/2023 12/31/2024 12/31/2025 Granted 380,957 516,852 1,057,173 Fair Value of Units on Grant Date (in thousands) $ 6,389 $ 6,872 $ 7,125 The Company values each RPSU on its grant date using a Monte Carlo simulation. The fair values of each award are being amortized over the three year performance period. For the 2021 and prior awards, dividend equivalents are credited as additional RPSUs during the performance period, subject to the same terms and conditions as the original RPSUs. The performance period will be abbreviated and the determination and delivery of earned shares will be accelerated in the event of a change in control or if the recipient of the award were to die, become disabled or retire in a qualifying retirement prior to the end of the otherwise applicable three year performance period; provided that, in the case of qualifying retirement for the 2020 and later grants, the number of shares deliverable will be pro-rated based on the portion of the performance period actually worked before retirement. In accordance with the accounting standard for share-based compensation, the Company amortizes stock-based compensation costs for the 2019 and prior RPSU grants through the qualifying retirement date for those executives who meet the conditions for qualifying retirement during the scheduled vesting period. For the year ended December 31, 2023, the Company recognized amortization of the 2023, 2022 and 2021 RPSU awards of $6.9 million, of which $0.9 million was capitalized consistent with the Company’s policies for capitalizing eligible portions of employee compensation. For the year ended December 31, 2022, amortization for the 2022, 2021 and 2020 RPSU awards was $6.2 million, of which $1.1 million was capitalized consistent with the Company’s policies for capitalizing eligible portions of employee compensation. For the year ended December 31, 2021, amortization for the 2021, 2020, and 2019 RPSU awards was $4.3 million, of which $0.5 million was capitalized consistent with the Company’s policies for capitalizing eligible portions of employee compensation. The remaining compensation expense to be recognized with respect to the non-vested RPSUs at December 31, 2023 was approximately $7.5 million and is expected to be recognized over a weighted average remaining vesting period of 1.4 years. The Company issued 171,318 common shares on February 1, 2023 in settlement of RPSUs that had been awarded on March 5, 2020 (with a three-year measurement period ended December 31, 2022 ). Holders of these RPSUs also received a cash dividend of $0.19 per share for these common shares on January 19, 2023. Employee Share Purchase Plan The Parent Company’s shareholders approved the 2007 Non-Qualified Employee Share Purchase Plan (the “ESPP”), which is intended to provide eligible employees with a convenient means to purchase common shares of the Parent Company through payroll deductions and voluntary cash purchases at an amount equal to 85% of the average closing price per share for a specified period. Under the plan document, the maximum participant contribution for the 2023 plan year is limited to the lesser of 20% of compensation or $50,000. The ESPP allows the Parent Company to make open market purchases, which reflects all purchases made under the plan to date. In addition, the number of shares separately reserved for issuance under the ESPP is 1.25 million . E mployees made purchases under the ESPP of $0.4 million during the year ended December 31, 2023, $0.6 million during the year ended December 31, 2022 and $0.6 million during the year ended December 31, 2021. The Company recognized $0.1 million of compensation expense related to the ESPP during the year ended December 31, 2023 , $0.02 million for the year ended December 31, 2022, and $0.1 million for the year ended December 31, 2021. Compensation expense represents the 15% discount on the purchase price. The Board of Trustees of the Parent Company may terminate the ESPP at its sole discretion at any time. Deferred Compensation In January 2005, the Parent Company adopted a Deferred Compensation Plan (the “Plan”) that allows trustees and certain key employees to defer compensation voluntarily. Compensation expense is recorded for the deferred compensation and a related liability is recognized. Participants may elect designated benchmark investment options for the notional investment of their deferred compensation. The deferred compensation obligation is adjusted for deemed income or loss related to the investments selected. At the time the participants defer compensation, the Company records a liability, which is included in the Company’s consolidated balance sheets. The liability is adjusted for changes in the market value of the participant-selected investments at the end of each accounting period, and the impact of adjusting the liability is recorded as an increase or decrease to compensation cost. The Company has purchased mutual funds which can be utilized as a funding source for the Company’s obligations under the Plan. Participants in the Plan have no interest in any assets set aside by the Company to meet its obligations under the Plan. For each of the years ended December 31, 2023, December 31, 2022 and December 31, 2021, the Company recorded a nominal amount of deferred compensation costs, net of investments in the company-owned policies and mutual funds. Participants in the Plan may elect to have all, or a portion of their deferred compensation invested in the Company’s common shares. The Company holds these shares in a rabbi trust, which is subject to the claims of the Company’s creditors in the event of the Company’s bankruptcy or insolvency. The Plan does not permit diversification of a participant’s deferral allocated to the Company common shares and deferrals allocated to Company common shares can only be settled with a fixed number of shares. In accordance with the accounting standard for deferred compensation arrangements where amounts earned are held in a rabbi trust and invested, the deferred compensation obligation associated with the Company’s common shares is classified as a component of shareholder’s equity and the related shares are treated as shares to be issued and are included in total shares outstanding. At both December 31, 2023 and 2022, 1.2 million of such shares were included in total shares outstanding, respectively. Subsequent changes in the fair value of the common shares are not reflected in operations or shareholders’ equity of the Company.

DISTRIBUTIONS

DISTRIBUTIONS	12 Months Ended
	Dec. 31, 2023
Distributions [Abstract]
DISTRIBUTIONS	16. DISTRIBUTIONS The following table provides the tax characteristics of the 2023, 2022 and 2021 distributions paid: Years ended December 31, 2023 2022 2021 (in thousands, except per share amounts) Common Share Distributions: Ordinary income $ 0.39 $ 0.47 $ 0.64 Capital gain 0.03 0.29 0.01 Non-taxable distributions 0.30 — 0.11 Distributions per share $ 0.72 $ 0.76 $ 0.76 Percentage classified as ordinary income 54.40 % 62.10 % 83.90 % Percentage classified as capital gain 4.00 % 37.90 % 1.20 % Percentage classified as non-taxable distribution 41.60 % — % 14.90 %

INCOME TAXES AND TAX CREDIT TRA

INCOME TAXES AND TAX CREDIT TRANSACTIONS	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
INCOME TAXES AND TAX CREDIT TRANSACTIONS	17. INCOME TAXES AND TAX CREDIT TRANSACTIONS Income Tax Provision/Benefit The Company accounts for income taxes using the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to the differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases, and for net operating loss, capital loss and tax credit carryforwards. The deferred tax assets and liabilities are measured using the enacted income tax rates in effect for the year in which those temporary differences are expected to be realized or settled. The effect on the deferred tax assets and liabilities from a change in tax rates is recognized in earnings in the period when the new rate is enacted. However, deferred tax assets are recognized only to the extent that it is more likely than not that they will be realized based on consideration of all available evidence, including the future reversals of existing taxable temporary differences, future projected taxable income and tax planning strategies. Valuation allowances are provided if, based upon the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. As of December 31, 2023 and 2022 there were no deferred tax assets included within “Other assets” in the consolidated balance sheets. The Company had no accruals for tax uncertainties as of December 31, 2023 and December 31, 2022. For the years ended December 31, 2023 2022 and 2021, there was no deferred income tax expense and de minimis current income tax expense. These amounts are included in “Income tax provision” in the consolidated statements of operations.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	18. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The following table details the components of accumulated other comprehensive income (loss) of the Parent Company and the Operating Partnership as of and for the three years ended December 31, 2023 (in thousands): Parent Company Cash Flow Hedges Balance at January 1, 2021 $ (7,561) Change in fair market value during year 4,817 Allocation of unrealized (gains)/losses on derivative financial instruments to noncontrolling interests (28) Amortization of interest rate contracts reclassified from comprehensive income to interest expense 752 Balance at December 31, 2021 $ (2,020) Change in fair market value during year 5,371 Allocation of unrealized (gains)/losses on derivative financial instruments to noncontrolling interests (18) Amortization of interest rate contracts reclassified from comprehensive income to interest expense 564 Balance at December 31, 2022 $ 3,897 Change in fair market value during year (4,579) Allocation of unrealized (gains)/losses on derivative financial instruments to noncontrolling interests 14 Amortization of interest rate contracts reclassified from comprehensive income to interest expense — Balance at December 31, 2023 $ (668) Operating Partnership Cash Flow Hedges Balance at January 1, 2021 $ (7,935) Change in fair market value during year 4,817 Amortization of interest rate contracts reclassified from comprehensive income to interest expense 752 Balance at December 31, 2021 $ (2,366) Change in fair market value during year 5,371 Amortization of interest rate contracts reclassified from comprehensive income to interest expense 564 Balance at December 31, 2022 $ 3,569 Change in fair market value during year (4,579) Amortization of interest rate contracts reclassified from comprehensive income to interest expense — Balance at December 31, 2023 $ (1,010)

SEGMENT INFORMATION

SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
SEGMENT INFORMATION	19. SEGMENT INFORMATION As of December 31, 2023, the Company owns and manages properties within four segments: (1) Philadelphia Central Business District (“Philadelphia CBD”), (2) Pennsylvania Suburbs, (3) Austin, Texas and (4) 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 Other segment includes properties located in Washington, D.C., Northern Virginia, Southern Maryland, Camden County, New Jersey and New Castle County, Delaware. In addition to the four 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 Company’s segments are based on the Company’s method of internal reporting which classifies its operations by geographic area. Beginning on January 1, 2023, the properties that were historically part of the Company's Metropolitan Washington, D.C. segment are reflected in the Company's Other reportable segment. The operations for the former Metropolitan Washington, D.C. segment for the twelve months ended December 31, 2022 and December 31, 2021 and real estate investments as of December 31, 2023 and December 31, 2022 as detailed below, have been included in the Other reportable segment. The following tables provide selected asset information and results of operations of the Company’s reportable segments (in thousands): Real estate investments, at cost: December 31, 2023 December 31, 2022 Philadelphia CBD $ 1,534,893 $ 1,517,801 Pennsylvania Suburbs 900,230 878,546 Austin, Texas 801,973 851,835 Total Core Segments 3,237,096 3,248,182 Other 305,136 369,058 Operating Properties $ 3,542,232 $ 3,617,240 Corporate Right of use asset - operating leases, net $ 19,031 $ 19,664 Construction-in-progress $ 135,529 $ 218,869 Land held for development $ 82,510 $ 76,499 Prepaid leasehold interests in land held for development, net $ 27,762 $ 35,576 . Net operating income: Year Ended December 31, 2023 2022 2021 Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income Philadelphia CBD $ 230,933 $ (79,579) $ 151,354 $ 220,876 $ (79,827) $ 141,049 $ 207,858 $ (73,695) $ 134,163 Pennsylvania Suburbs 129,300 (39,584) 89,716 128,940 (41,814) 87,126 124,566 (40,011) 84,555 Austin, Texas 95,505 (38,453) 57,052 96,328 (41,141) 55,187 101,680 (39,374) 62,306 Other 39,306 (21,134) 18,172 36,610 (21,165) 15,445 33,880 (25,226) 8,654 Corporate 19,607 (11,197) 8,410 23,346 (10,454) 12,892 18,835 (10,005) 8,830 Operating properties $ 514,651 $ (189,947) $ 324,704 $ 506,100 $ (194,401) $ 311,699 $ 486,819 $ (188,311) $ 298,508 (a) Includes property operating expense, real estate taxes and third party management expense. Unconsolidated real estate ventures: Investment in real estate ventures, at equity Equity in income (loss) of real estate venture As of Year ended December 31, December 31, 2023 December 31, 2022 2023 2022 2021 Philadelphia CBD $ 450,136 $ 387,301 $ (25,793) $ (11,764) $ (15,191) Mid-Atlantic Office JV — 31,005 (26,448) 412 932 MAP Venture (48,733) (35,411) (10,581) (8,340) (8,683) Austin, Texas 79,160 65,426 — — — Other $ 71,931 $ 83,903 $ (15,093) $ (2,324) $ (3,755) Total $ 552,494 $ 532,224 $ (77,915) $ (22,016) $ (26,697) Net operating income (“NOI”) is a non-GAAP financial measure, which we define as total revenue less property operating expenses, real estate taxes, and third party management expenses. Property operating expenses that are included in determining NOI consist of costs that are necessary and allocable to our operating properties such as utilities, property-level salaries, repairs and maintenance, property insurance and management fees. General and administrative expenses that are not reflected in NOI primarily consist of corporate-level salaries, amortization of share awards and professional fees that are incurred as part of corporate office management. NOI presented by the Company may not be comparable to NOI reported by other companies that define NOI differently. NOI is the primary measure that is used by the Company's management to evaluate the operating performance of the Company's real estate assets by segment. The Company believes NOI provides useful information to investors regarding the financial condition and results of operations because it reflects only those income and expense items that are incurred at the property level. While NOI is a relevant and widely used measure of operating performance of real estate investment trusts, it does not represent cash flow from operations or net income as defined by GAAP and should not be considered as an alternative to those measures in evaluating our liquidity or operating performance. NOI does not reflect interest expenses, real estate impairment losses, depreciation and amortization costs, capital expenditures and leasing costs. The Company believes that net income (loss), as defined by GAAP, is the most appropriate earnings measure. The following is a reconciliation of consolidated net income (loss), as defined by GAAP, to consolidated NOI, (in thousands): Year Ended December 31, 2023 2022 2021 Net income (loss) $ (197,403) $ 53,992 $ 12,366 Plus: Interest expense 95,456 68,764 62,617 Interest expense - amortization of deferred financing costs 4,369 3,091 2,836 Depreciation and amortization 188,797 177,984 178,105 General and administrative expenses 34,862 35,006 30,153 Equity in loss of unconsolidated real estate ventures 77,915 22,016 26,697 Provision for impairment 131,573 4,663 — Gain (loss) on early extinguishment of debt (138) 435 — Less: Interest and investment income 1,671 1,905 8,295 Income tax provision (72) (55) (47) Net gain on disposition of real estate 7,736 17,677 142 Net gain on sale of undepreciated real estate 1,211 8,007 2,903 Net gain on real estate venture transactions 181 26,718 2,973 Consolidated net operating income $ 324,704 $ 311,699 $ 298,508

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	20. COMMITMENTS AND CONTINGENCIES Legal Proceedings The Company is involved from time to time in litigation on various matters, including disputes with tenants, disputes with vendors, employee disputes and disputes arising out of agreements to purchase or sell properties or joint ventures or disputes relating to state and local taxes. Given the nature of the Company’s business activities, these lawsuits are considered routine to the conduct of its business. The result of any particular lawsuit cannot be predicted, because of the very nature of litigation, the litigation process and its adversarial nature, and the jury system. The Company will establish reserves for specific legal proceedings when it determines that the likelihood of an unfavorable outcome is probable and when the amount of loss is reasonably estimable. The Company does not expect that the liabilities, if any, that may ultimately result from such legal actions will have a material adverse effect on the consolidated financial position, results of operations or cash flows of the Company. Environmental As an owner of real estate, the Company is subject to various environmental laws of federal, state, and local governments. The Company’s compliance with existing laws has not had a material adverse effect on its financial condition and results of operations, and the Company does not believe it will have a material adverse effect in the future. However, the Company cannot predict the impact of unforeseen environmental contingencies or new or changed laws or regulations on its current Properties or on properties that the Company may acquire. Debt Guarantees As of December 31, 2023, the Company's unconsolidated real estate ventures had aggregate indebtedness of $1,412.8 million. These loans are generally mortgage or construction loans, most of which are nonrecourse to the Company, except for customary recourse carve-outs. In addition, during construction undertaken by the unconsolidated real estate ventures, the Company has provided, and expects to continue to provide, cost overrun completion carry limited payment and guarantees, as well as customary environmental indemnities and guarantees of customary exceptions to nonrecourse provisions in loan agreements and in certain circumstances, joint venture agreements. See also Note 4, “Investment in Unconsolidated Real Estate Ventures,” for information on the guarantees in favor of the lenders on the construction loans for the One Uptown Ventures. Impact of Natural Disasters and Casualty The Company carries liability insurance to mitigate its exposure to certain losses, including those relating to property damage. The Company records the estimated amount of expected insurance proceeds for property damage and other losses incurred as an asset (typically a receivable from the insurer) and income up to the amount of the losses incurred when receipt of insurance proceeds is deemed probable. Any amount of insurance recovery in excess of the amount of the losses is considered a gain contingency and is not recorded until the proceeds are received. In February 2021, one of the Company's properties in Austin, Texas sustained damage from the winter storms and resulting power grid failures. As a result of the damage, during the year ended December 31, 2021, the Company recorded a fixed asset write-off totaling $1.2 million. During the year ended December 31, 2021, the Company has recorded an estimated $7.2 million of restoration costs, of which $1.9 million is included in Accounts payable and accrued expenses on the consolidated balance sheets as of December 31, 2021. The Company has also sustained business interruption loss of $3.9 million related to unpaid rent, which is also fully covered under the insurance policy. During the year ended December 31, 2021, the Company received $15.3 million of insurance proceeds, resulting in full recovery of the costs incurred to date. The $3.0 million of insurance proceeds received in excess of the fixed asset write-off, total business interruption, and total estimated restoration cost during the year ended December 31, 2021 is included in Other income on the consolidated statement of operations. During year ended December 31, 2022, the Company recognized a $0.8 million reduction of the previously estimated restoration costs and also received $2.8 million of additional insurance proceeds. The reduction of the restoration costs and additional insurance proceeds are included in other income on the consolidated statement of operations. Other Commitments or Contingencies Under the terms of each of the One Uptown joint venture agreements, the Company has provided cost overrun and completion guarantees, as well as customary environmental indemnities, in favor of the joint venture partner, for each of the One Uptown joint ventures. See Note 4, “Investment in Unconsolidated Real Estate Ventures” for further information. In connection with the Schuylkill Yards Project, the Company entered into a neighborhood engagement program and, as of December 31, 2023, had $6.2 million of future fixed contractual obligations. The Company also committed to fund additional contributions under the program. As of December 31, 2023, the Company estimates that these additional contributions, which are not fixed under the terms of agreement, will be $2.2 million. In connection with the formation of the Commerce Square Venture, the Company has committed to investing an additional $20.0 million of preferred equity in the properties on a pari passu basis with its joint venture partner of which $9.5 million has been contributed by the Company as of December 31, 2023. As part of the Company’s September 2004 acquisition of a portfolio of properties (which the Company refers to as the “TRC acquisition”), the Company acquired its interest in Two Logan Square, a 708,844 square foot office building in Philadelphia, Pennsylvania primarily through its ownership of a second and third mortgage secured by this property. This property is consolidated, as the borrower is a variable interest entity and the Company, through its ownership of the second and third mortgages, is the primary beneficiary. On October 21, 2020, the Company also acquired the $79.8 million first mortgage on the property from the third-party mortgage lender pursuant to an agreement with certain of the former owners. Under the agreement, the Company has agreed to not take title to Two Logan until the earlier of June 2026 or the occurrence of certain events related to the ownership interests of certain former owners. If the Company were to sell the restricted property before the expiration of the restricted period in a non-exempt transaction, the Company may be required to make significant payments to certain of the former owners of Two Logan Square on account of tax liabilities attributed to them. Additionally, the Company will be required to pay these certain former owners an amount estimated at approximately $0.6 million to redeem their residual interest in the fee owner of this property. The $0.6 million payment is included within “Other liabilities” on the consolidated balance sheets. The Company has also committed $15.0 million to a newly-formed venture capital fund investing in early-stage life science companies. 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.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2023
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II Valuation and Qualifying Accounts	Schedule II Valuation and Qualifying Accounts (in thousands) Description Balance at Beginning of Year Additions Deductions (1) Balance at End of Year Allowance for doubtful accounts: December 31, 2023 $ 3,947 $ — $ 1,275 $ 2,672 December 31, 2022 $ 4,133 $ — $ 186 $ 3,947 December 31, 2021 $ 5,086 $ — $ 953 $ 4,133 (1)

Schedule III - Real Estate and

Schedule III - Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2023
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Real Estate and Accumulated Depreciation	BRANDYWINE REALTY TRUST AND BRANDYWINE OPERATING PARTNERSHIP, L.P. Schedule III Real Estate and Accumulated Depreciation — December 31, 2023 (in thousands) Initial Cost Gross Amount Which Carried Property Name City State Encumbrances Land Building & Improvements Net Improvements (Retirements) Since Acquisition Land Building & Improvements Total (a) Accumulated Depreciation at December 31, 2023 (b) Year of Construction Year Acquired Depreciable Life PENNSYLVANIA SUBURBS Six Tower Bridge (181 Washington Street) Conshohocken PA $ — $ 6,927.00 $ 14,722.00 $ 1,330.00 $ 6,237.00 $ 16,742.00 $ 22,979.00 $ 5,108.00 1999 2013 (c) 426 Lancaster Avenue Devon PA — 1,689 6,756 9,405 1,686 16,164 17,850 3,841 1990 1998 (c) 640 Freedom Business Center (d) King Of Prussia PA — 1,015 20,098 4,762 305 25,570 25,875 17,737 1991 1998 (c) 620 Freedom Business Center (d) King Of Prussia PA — 666 13,118 3,160 199 16,745 16,944 10,756 1986 1998 (c) 1000 First Avenue King Of Prussia PA — — 13,708 3,345 — 17,053 17,053 13,278 1980 1998 (c) 1060 First Avenue King Of Prussia PA — — 13,665 4,134 — 17,799 17,799 13,769 1987 1998 (c) 630 Freedom Business Center Drive (d) King Of Prussia PA — 666 13,251 3,182 201 16,898 17,099 11,422 1989 1998 (c) 1020 First Avenue King Of Prussia PA — — 10,744 4,544 — 15,288 15,288 11,736 1984 1998 (c) 1040 First Avenue King Of Prussia PA — — 14,142 5,065 — 19,207 19,207 14,973 1985 1998 (c) 610 Freedom Business Center Drive King Of Prussia PA — 485 9,602 1,615 146 11,556 11,702 8,089 1985 1998 (c) 650 Park Avenue King Of Prussia PA — 1,916 4,378 (4,378) 1,916 — 1,916 — 1968 1998 (c) 600 Park Avenue King Of Prussia PA — 1,012 4,048 — 1,012 4,048 5,060 2,706 1964 1998 (c) 933 First Avenue King Of Prussia PA 15,960 3,127 20,794 (1,125) 3,127 19,669 22,796 5,692 2017 N/A (c) 500 North Gulph Road King Of Prussia PA 16,121 1,303 5,201 21,471 1,303 26,672 27,975 5,854 1979 1996 (c) 401 Plymouth Road Plymouth Meeting PA — 6,199 16,131 15,706 6,199 31,837 38,036 16,202 2001 2000 (c) Metroplex (4000 Chemical Road) Plymouth Meeting PA 16,055 4,373 24,546 5,554 4,373 30,100 34,473 11,076 2007 2001 (c) Metroplex II Plymouth Meeting PA — — — 569 — 569 569 6 NA 2001 (c) Metroplex III Plymouth Meeting PA — — — 317 — 317 317 4 NA 2005 610 West Germantown Pike Plymouth Meeting PA — 3,651 14,514 254 3,051 15,368 18,419 7,768 1987 2002 (c) 600 West Germantown Pike Plymouth Meeting PA — 3,652 15,288 (415) 3,052 15,473 18,525 7,992 1986 2002 (c) 630 West Germantown Pike Plymouth Meeting PA — 3,558 14,743 (673) 2,973 14,655 17,628 7,757 1988 2002 (c) 620 West Germantown Pike Plymouth Meeting PA — 3,572 14,435 1,156 2,985 16,178 19,163 7,802 1990 2002 (c) 660 West Germantown Pike Plymouth Meeting PA — 3,694 5,487 14,871 4,517 19,535 24,052 7,784 1987 2012 (c) 351 Plymouth Road Plymouth Meeting PA — 1,043 555 — 1,043 555 1,598 260 N/A 2000 (c) 150 Radnor Chester Road Radnor PA — 11,925 36,986 22,327 11,897 59,341 71,238 30,253 1983 2004 (c) One Radnor Corporate Center Radnor PA — 7,323 28,613 4,133 7,323 32,746 40,069 19,410 1998 2004 (c) 201 King of Prussia Road Radnor PA — 8,956 29,811 4,939 8,949 34,757 43,706 24,432 2001 2004 (c) 555 Lancaster Avenue Radnor PA — 8,014 16,508 12,652 8,609 28,565 37,174 10,733 1973 2004 (c) Four Radnor Corporate Center Radnor PA — 5,406 21,390 6,719 5,705 27,810 33,515 16,857 1995 2004 (c) Five Radnor Corporate Center Radnor PA — 6,506 25,525 9,676 6,578 35,129 41,707 17,511 1998 2004 (c) Three Radnor Corporate Center Radnor PA — 4,773 17,961 2,740 4,791 20,683 25,474 12,840 1998 2004 (c) Two Radnor Corporate Center Radnor PA — 3,937 15,484 5,195 3,942 20,674 24,616 11,281 1998 2004 (c) 130 Radnor Chester Road Radnor PA — 2,573 8,338 (258) 2,567 8,086 10,653 4,324 1983 2004 (c) 170 Radnor Chester Road Radnor PA — 2,514 8,147 2,344 2,509 10,496 13,005 5,860 1983 2004 (c) 101 West Elm Street W. Conshohocken PA — 6,251 25,209 2,600 6,251 27,809 34,060 13,040 1999 2005 (c) 1 West Elm Street W. Conshohocken PA — 3,557 14,249 9,139 3,557 23,388 26,945 8,417 1999 2005 (c) 250 King of Prussia Road (e) Radnor PA — — 20,566 65,182 11,200 74,548 85,748 4,666 N/A 2022 (c) Initial Cost Gross Amount Which Carried Property Name City State Encumbrances Land Building & Improvements Net Improvements (Retirements) Since Acquisition Land Building & Improvements Total (a) Accumulated Depreciation at December 31, 2023 (b) Year of Construction Year Acquired Depreciable Life PHILADELPHIA CBD Cira Centre (2929 Arch Street) Philadelphia PA — — 208,570 38,189 12,586 234,173 246,759 82,593 2005 N/A (c) Three Logan Square (1717 Arch Street) Philadelphia PA — — 98,188 87,145 25,195 160,138 185,333 68,452 1990 2010 (c) One Logan Square (130 North 18th Street) Philadelphia PA — 14,496 107,736 23,882 14,473 131,641 146,114 75,119 1998 2004 (c) Two Logan Square (100 North 18th Street) Philadelphia PA — 16,066 100,255 34,756 16,066 135,011 151,077 67,090 1988 2004 (c) Cira Centre South Garage (129 South 30th Street) (d) Philadelphia PA — — 76,008 26,881 6,549 96,340 102,889 30,503 2010 N/A (c) 1900 Market Street Philadelphia PA 61,703.00 7,768 17,263 61,721 7,768 78,984 86,752 35,534 1981 2012 (c) 3020 Market Street Philadelphia PA — — 21,417 6,005 — 27,422 27,422 13,339 1959 2011 (c) 618-634 Market Street Philadelphia PA — 13,365 5,791 5,161 13,365 10,952 24,317 7,610 1966 2015 (c) FMC Tower at Cira Centre South (2929 Walnut Street) Philadelphia PA — — 400,294 10,819 — 411,113 411,113 100,935 2016 N/A (c) 2100 Market Street Philadelphia PA — 18,827 — 6,318 18,854 6,291 25,145 2,715 N/A 2015 (c) 1505-11 Race Street Philadelphia PA — 3,662 6,061 8 3,670 6,061 9,731 480 1922 2020 (c) 3000 Market Street (f) Philadelphia PA — 18,924 13,080 17,349 18,924 30,429 49,353 4,739 1937 2017 (c) The Bulletin Building (3025 Market Street) (f) Philadelphia PA 49,429.00 — 24,377 44,435 — 68,812 68,812 15,078 1953 2017 (c) 3001-3003 JFK Boulevard (g) Philadelphia PA — — — 85 — 85 85 38 N/A 2018 N/A AUSTIN, TX 401-405 Colorado Street Austin TX 62,688 — 106,828 564 — 107,392 107,392 5,958 2022 N/A (c) 11501 Burnet Road - Building 1 Austin TX — 3,755 22,702 4 3,755 22,706 26,461 11,689 1991 2015 (c) 11501 Burnet Road - Building 2 Austin TX — 2,732 16,305 733 2,732 17,038 19,770 8,991 1991 2015 (c) 11501 Burnet Road - Building 3 Austin TX — 3,688 22,348 7,118 3,688 29,466 33,154 13,671 1991 2015 (c) 11501 Burnet Road - Building 4 Austin TX — 2,614 15,740 3 2,614 15,743 18,357 8,105 1991 2015 (c) 11501 Burnet Road - Building 5 Austin TX — 3,689 22,354 4 3,689 22,358 26,047 11,511 1991 2015 (c) 11501 Burnet Road - Building 6 Austin TX — 2,676 15,972 14,114 2,676 30,086 32,762 16,346 1991 2015 (c) 11501 Burnet Road - Building 8 Austin TX — 1,400 7,422 1,776 1,400 9,198 10,598 4,742 1991 2015 (c) 11501 Burnet Road - Parking Garage Austin TX — — 19,826 1,588 — 21,414 21,414 11,364 1991 2015 (c) Four Points Centre 3 (11120 Four Points Drive) Austin TX 23,044 1,140 — 40,322 1,141 40,321 41,462 8,637 2019 2013 (c) One Barton Skyway (1501 South MoPac Expressway) Austin TX — 10,496 47,670 8,189 10,495 55,860 66,355 8,647 1999 2018 (c) Two Barton Skyway (1601 South MoPac Expressway) Austin TX — 10,849 53,868 3,784 10,848 57,653 68,501 9,099 2000 2018 (c) Four Barton Skyway (1301 South MoPac Expressway) Austin TX — 13,301 57,041 7,895 13,300 64,937 78,237 9,367 2001 2018 (c) Four Points Centre (11305 Four Points Drive) Austin TX — 7,800 43,581 4,622 7,800 48,203 56,003 7,977 2008 2018 (c) River Place - Building 1 (6500 River Place Boulevard) Austin TX — 2,004 17,680 990 2,004 18,670 20,674 2,822 2000 2018 (c) River Place - Building 2 (6500 River Place Boulevard) Austin TX — 3,137 29,254 1,508 3,137 30,762 33,899 4,338 2000 2018 (c) River Place - Building 3 (6500 River Place Boulevard) Austin TX — 3,064 26,705 1,195 3,064 27,900 30,964 3,753 2000 2018 (c) River Place - Building 4 (6500 River Place Boulevard Austin TX — 2,273 18,617 1,140 2,273 19,757 22,030 2,684 2000 2018 (c) River Place - Building 5 (6500 River Place Boulevard) Austin TX — 1,752 14,315 736 1,752 15,051 16,803 2,218 2001 2018 (c) River Place - Building 6 (6500 River Place Boulevard) Austin TX — 1,598 12,945 703 1,598 13,648 15,246 2,044 2001 2018 (c) Initial Cost Gross Amount Which Carried Property Name City State Encumbrances Land Building & Improvements Net Improvements (Retirements) Since Acquisition Land Building & Improvements Total (a) Accumulated Depreciation at December 31, 2023 (b) Year of Construction Year Acquired Depreciable Life River Place - Building 7 (6500 River Place Boulevard) Austin TX — 1,801 16,486 1,374 1,801 17,860 19,661 3,146 2002 2018 (c) Quarry Lake II (4516 Seton Center Parkway) Austin TX — 3970 30546 1678 3867 32327 36194 4541 1998 2018 (c) OTHER 6600 Rockledge Drive Bethesda MD — — 37,421 (14,597) — 22,824 22,824 9,299 1981 2006 (c) 1676 International Drive Mclean VA — 18,437 97,538 (30,581) 10,239 75,155 85,394 22,630 1999 2006 (c) 8260 Greensboro Drive Mclean VA — 7,952 33,964 10,969 8,102 44,783 52,885 15,881 1980 2006 (c) 2340 Dulles Corner Boulevard Herndon VA — 16,345 65,379 (23,353) 9,747 48,624 58,371 1,192 1988 2006 (c) Dabney Land Westwood Richmond VA — 1,732 — 3,690 819 4,706 5,525 493 NA 1998 Main Street - Plaza 1000 Voorhees NJ — 2,732 10,942 284 2,732 11,226 13,958 11,073 1988 1997 (c) Main Street - Piazza Voorhees NJ — 696 2,802 2,762 704 5,556 6,260 4,042 1990 1997 (c) Main Street - Promenade Voorhees NJ — 532 2,052 265 532 2,317 2,849 1,599 1988 1997 (c) 920 North King Street Wilmington DE — 6,141 21,140 7,272 6,141 28,412 34,553 17,591 1989 2004 (c) 300 Delaware Avenue Wilmington DE — 6,369 13,739 2,386 6,366 16,128 22,494 10,881 1989 2004 (c) Total: $ 245,000 $ 358,066 $ 2,520,935 $ 663,128 $ 394,669 $ 3,147,563 $ 3,542,232 $ 1,131,792 Reconciliation of Real Estate: The following table reconciles the real estate investments from January 1, 2021 to December 31, 2023 (in thousands): 2023 2022 2021 Balance at beginning of year $ 3,617,240 $ 3,472,602 $ 3,474,109 Additions: Acquisitions — — — Capital expenditures and assets placed into service 210,226 212,874 134,931 Less: Dispositions/impairments/placed into redevelopment (251,190) (32,951) (82,247) Retirements (34,044) (35,285) (54,191) Balance at end of year $ 3,542,232 $ 3,617,240 $ 3,472,602 Per consolidated balance sheet $ 3,542,232 $ 3,617,240 $ 3,472,602 The aggregate cost for federal income tax purposes is $3.0 billion as of December 31, 2023. (c) Reconciliation of Accumulated Depreciation: The following table reconciles the accumulated depreciation on real estate investments from January 1, 2021 to December 31, 2023 (in thousands): 2023 2022 2021 Balance at beginning of year $ 1,063,060 $ 957,450 $ 896,561 Additions: Depreciation expense 158,194 147,735 136,171 Less: Dispositions/impairments/placed into redevelopment (55,969) (7,341) (24,440) Retirements (33,493) (34,784) (50,842) Balance at end of year $ 1,131,792 $ 1,063,060 $ 957,450 Per consolidated balance sheet $ 1,131,792 $ 1,063,060 $ 957,450 (d) Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 55 years. (e) Land value represents unamortized prepaid ground lease. (f) 250 King of Prussia Road was fully placed into service in 2023. (g) Reflects original construction date. Significant improvements were made to 3000 Market Street in 1988 and to The Bulletin Building in 2012. (h)

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net income (loss)	$ (196,789)	$ 53,824	$ 12,289

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The Company consolidates variable interest entities (“VIEs”) in which it is considered to be the primary beneficiary. VIEs are entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial support or that the holders of the equity investment at risk do not have a controlling financial interest. The primary beneficiary is defined by the entity having both of the following characteristics: (i) the power to direct those matters that most significantly impact the activities of the VIE and (ii) the obligation to absorb losses or the right to receive benefits of the VIE that could potentially be significant to the VIE. For entities that the Company has the obligations to fund losses, its maximum exposure to loss is not limited to the carrying amount of its investments. When an entity is not deemed to be a VIE, the Company consolidates entities for which it has significant decision making control over the entity’s operations. The Company’s judgment with respect to its level of influence or control of an entity involves consideration of various factors including the form of the Company’s ownership interest, its representation in the entity’s governance, the size of its investment (including loans), estimates of future cash flows, its ability to participate in policy making decisions and the rights of the other investors to participate in the decision making process and to replace the Company as manager and/or liquidate the venture, if applicable. The Company’s assessment of its influence or control over an entity affects the presentation of these investments in the Company’s consolidated financial statements. In addition to evaluating control rights, the Company consolidates entities in which the outside partner has no substantive kick-out rights to remove the Company as managing member. The portion of the consolidated entities that are not owned by the Company is presented as noncontrolling interest as of and during the periods consolidated. All intercompany transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
Operating Properties	Operating Properties Operating properties are carried at historical cost less accumulated depreciation and impairment losses. The value of operating properties reflects their purchase price or development cost. Acquisition costs related to business combinations are expensed as incurred, whereas the costs related to asset acquisitions are capitalized as incurred. Costs incurred for the renovation and betterment of an operating property are capitalized to the Company’s investment in that property. Ordinary repairs and maintenance are expensed as incurred.
Purchase Price Allocation	Purchase Price Allocation For acquisitions of real estate or in-substance real estate that are accounted for as business combinations, we recognize the assets acquired (including the intangible value of acquired above- or below-market leases, acquired in-place leases and tenant relationship values), liabilities assumed, noncontrolling interests, and previously existing ownership interests at fair value as of the acquisition date. Any excess (deficit) of the consideration transferred relative to the fair value of the net assets acquired is accounted for as goodwill (bargain purchase gain). Acquisition costs related to business combinations are expensed as incurred. Acquisitions of real estate and in-substance real estate that do not meet the definition of a business are accounted for as asset acquisitions. The Company generally expects that acquisitions of real estate or in-substance real estate will not meet the definition of business and therefore are accounted for as asset acquisitions, unless specifically noted otherwise. The accounting model for asset acquisitions is similar to the accounting model for business combinations except that the acquisition consideration (including acquisition costs) is allocated to the individual assets acquired and liabilities assumed on a relative fair value basis. As a result, asset acquisitions do not result in recognition of goodwill or a bargain purchase gain. Additionally, because the accounting model for asset acquisitions is a cost accumulation model, preexisting interests in the acquired assets, if any, are not remeasured to fair value but continue to be accounted for at their historical cost. Direct acquisition costs are capitalized if an asset acquisition is probable. If we determine that an asset acquisition is no longer probable, no new costs are capitalized and all capitalized costs that are not recoverable are written off. The purchase price is allocated to the acquired assets and assumed liabilities, including land and buildings, as if vacant based on highest and best use for the acquired assets. The Company assesses and considers fair value of the operating properties based on estimated cash flow projections that utilize discount and/or capitalization rates that it deems appropriate, as well as available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known and anticipated trends, and market and economic conditions. The Company allocates the purchase price of properties considered to be business combinations and asset acquisitions to net tangible and identified intangible assets acquired based on fair values. Above-market and below-market in-place lease values for acquired properties are recorded based on the present value (using an interest rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to the in-place leases and (ii) the Company’s estimate of the fair market lease rates for the corresponding in-place leases, measured over a period equal to the remaining noncancellable term of the lease (including the below market fixed renewal periods that are considered probable, if applicable). Capitalized above-market lease values are amortized as a reduction of rental income over the remaining noncancellable terms of the respective leases. Capitalized below-market lease values are amortized as an increase to rental income over the remaining noncancellable terms of the respective leases, including any below market fixed-rate renewal option periods that are considered probable. Other intangible assets also include in-place leases based on the Company’s evaluation of the specific characteristics of each tenant’s lease and the Company’s overall relationship with the respective tenant. The Company estimates the cost to execute leases with terms similar to the remaining lease terms of the in-place leases, including leasing commissions, legal and other related expenses. This intangible asset is amortized to expense over the remaining term of the respective leases and any fixed-rate bargain renewal periods. Factors considered by the Company in this analysis include an estimate of the carrying costs during the expected lease-up periods considering current market conditions and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance, and other operating expenses, and estimates of lost rents at market rates during the expected lease-up periods, which primarily range from four In the event that a tenant terminates its lease, the unamortized portion of each intangible, including in-place lease values and tenant relationship values, is charged to expense and market rate adjustments (above or below) are recorded to revenue.
Depreciation and Amortization	Depreciation and Amortization The costs of buildings and improvements are depreciated using the straight-line method based on the following useful lives: buildings and improvements (5 to 55 years) and tenant improvements (the shorter of (i) the life of the asset (1 to 16 years) or (ii) the lease term).
Construction-in-Progress	Construction-in-Progress Project costs directly associated with the development or redevelopment and construction of a real estate project are capitalized as construction-in-progress. Construction-in-progress also includes costs related to ongoing tenant improvement projects. In addition, interest, real estate taxes, and other expenses that are directly associated with the Company’s
Ground Leases	Ground Leases The Company is the lessee under long-term ground leases classified as operating leases. The Company makes significant assumptions and judgments when determining the discount rate for the lease to calculate the present value of the lease payments. As the rate implicit in the lease is not readily determinable, the Company estimates the incremental borrowing rate (“IBR”) that it would need to pay to borrow, on a collateralized basis, an amount equal to the lease payments in a similar economic environment, over a similar lease term. The Company utilizes a market-based approach to estimate the IBR for each individual lease. The base IBR is estimated utilizing observable mortgage and corporate bond rates, which are then adjusted to account for considerations related to the Company’s credit rating and the lease term to select an incremental borrowing rate for each lease. The right of use assets and lease liabilities are presented as “Right of use asset - operating leases, net” and “Lease liability - operating leases”, respectively, on the consolidated balance sheet as of December 31, 2023 and 2022, respectively. The lease liabilities and right of use assets are amortized on a straight-line basis over the lease term with the corresponding expense classified in “Property operating expenses” on the consolidated statements of operations. The most recent CPI adjustment is used to determine the present value of the lease payments for an indexed lease and ultimately the right of use asset and corresponding lease liability. Rent payments for amounts in excess of this estimated growth rate will be expensed on a cash basis as incurred and are considered variable lease costs.
Impairment of Real Estate Investments	Impairment of Real Estate Investments The Company reviews its real estate investments for impairment following the end of each quarter for each of its real estate investments where events or changes in circumstances indicate that the carrying amounts may not be recoverable. The Company updates leasing and other assumptions regularly, paying particular attention to real estate investments where there is an event or change in circumstances that indicates an impairment in value. Additionally, the Company considers strategic decisions regarding the future development plans for real estate investment under development and other market factors. For real estate investments to be held and used, the Company analyzes recoverability based on the estimated undiscounted future cash flows expected to be generated from the operations and eventual disposition of the assets over, in most cases, a 10-year hold period. If there is significant possibility that the Company will dispose of assets earlier, it analyzes the recoverability using a probability weighted analysis of the undiscounted future cash flows expected to be generated from the operations and eventual disposition of each asset using various probable hold periods. If the recoverability analysis indicates that the carrying value of the tested real estate investment is not recoverable, the real estate investment is written down to its fair value and an impairment is recognized in the amount of the excess of the carrying amount of the asset over its fair value. If and when the Company’s plans change, it revises its recoverability analysis to use cash flows expected from operations and eventual disposition of each asset using hold periods that are consistent with its revised plans. Estimated future cash flows used in such analysis are based on the Company’s plans for the real estate investment and its views of market economic conditions. The estimates consider assumptions, including but not limited to market rental rates, capitalization rates, and recent sales data for comparable real estate investments. Future cash flows are discounted when determining fair value of an asset. Most of these assumptions are influenced by our direct experience with the real estate investments and their markets as well as market data obtained from real estate leasing and brokerage firms.
Assets Held for Sale	Assets Held for Sale The Company generally reclassifies assets to held for sale when the transaction has been approved by its Board of Trustees, or by officers vested with authority to approve the transaction, and there are no known significant contingencies relating to the sale of the real estate investment within one year of the consideration date and the consummation of the transaction is otherwise considered probable. When a real estate investment is designated as held for sale, the Company stops depreciating the real estate investment and estimates the real estate investment’s fair value, net of selling costs. If the determination is made that the estimated fair value, net of selling costs, is less than the net carrying value of the real estate investment, an impairment is recognized, reducing the net carrying value of the real estate investment to estimated fair value less selling costs. For periods in which a real estate investment is classified as held for sale, the Company classifies the assets and liabilities, as applicable, of the real estate investment as held for sale on the consolidated balance sheet for such periods.
Impairment of Land Held for Development	Impairment of Land Held for Development When demand for build-to-suit properties declines and the ability to sell land held for development deteriorates, or other market factors indicate possible impairment in the recoverability of land held for development, it is reviewed for impairment by comparing its fair value to its carrying value. If the estimated sales value is less than the carrying value, the carrying value is written down to its estimated fair value. Estimated fair value is generally determined using a market valuation approach, comparing the subject property to recent comparable market transactions in a similar location; or using estimated cash flows.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents are highly-liquid investments with original maturities of three months or less. The Company maintains cash equivalents in money market accounts with financial institutions in excess of insured limits, but believes this risk is mitigated by only investing in or through major financial institutions. The Company does not invest its available cash balances in money market funds. As such, available cash balances are appropriately reflected as cash and cash equivalents on the consolidated balance sheets.
Restricted Cash and Escrows	Restricted Cash and Escrows
Accounts Receivable And Accrued Rent Receivable	Accounts Receivable and Accrued Rent Receivable Generally, leases with tenants are accounted for as operating leases. Minimum lease payments under tenant leases are recognized on a straight-line basis over the term of the related lease. The cumulative difference between lease revenue recognized under the straight-line method and contractual lease payment terms are recorded as “Accrued rent receivable, net” on the consolidated balance sheets. Included in current tenant receivables are tenant reimbursements which are comprised of amounts recoverable from tenants for common area maintenance expenses and certain other recoverable expenses that are recognized as revenue in the period in which the related expenses are incurred.
Investments in Unconsolidated Real Estate Ventures	Investments in Unconsolidated Real Estate Ventures Under the equity method, investments in real estate ventures are recorded initially at cost and subsequently adjusted for equity in earnings, contributions, distributions, and impairments. The Company generally allocates income and losses from the unconsolidated real estate ventures based on the venture's distribution priorities, which may be different from its stated ownership percentage. For real estate ventures that are constructing assets to commence planned principal operations, the Company capitalizes interest expense to the extent that it is recoverable using the Company’s weighted average interest rate of consolidated debt and its investment balance as a basis. Planned principal operations commence when a property is available to lease and at that point in time, the Company ceases capitalizing interest to its investment basis. At least quarterly, management assesses whether there are any other than temporary impairment indicators of the Company’s investments in real estate ventures. If any indicators of impairment are present, we calculate the fair value of the investment in the unconsolidated real estate venture. An investment is other than temporarily impaired only if the fair value of the investment in a real estate venture, as estimated by management, is less than the carrying value and the decline is other than temporary. To the extent that an other than temporary impairment has occurred, an impairment charge is recorded in the amount of the excess of the carrying amount of the investment over the estimated fair value. Management is required to make significant judgments about the estimated fair value of its investments to determine if an impairment exists. Fair value is generally determined through income valuation approaches, including discounted cash flows and direct capitalization models or a sales comparison approach. When the Company acquires an interest in or contributes assets to a real estate venture project, the difference between the Company’s cost basis in the investment and the value of the real estate venture or asset contributed is amortized over the life of the related assets, intangibles, and liabilities and such adjustment is included in the Company’s share of equity in income of unconsolidated real estate ventures.
Deferred Costs	Deferred Costs Certain costs incurred in connection with property leasing are capitalized as deferred leasing costs. Deferred leasing costs consist primarily of third-party and internal leasing commissions that are amortized using the straight-line method over the life of the respective lease which generally ranges from 1 to 16 years. Management re-evaluates the remaining useful lives of leasing costs in conjunction with changes in the respective lease term.
Notes Receivable	Notes Receivable The Company accounts for notes receivable on its balance sheet at amortized cost, net of allowance for loan losses. Interest income is recognized over the term of the notes receivable and is calculated based on the contractual terms of each note agreement. At inception and on a quarterly basis, the Company evaluates notes receivable for the current estimate of expected credit losses over the contractual term using a probability-of-default method and reports in net income (as a credit loss expense) the amount necessary to adjust the allowance for credit losses to reflect management's current estimate. Management considers performance and/or value of the underlying collateral property as well as the financial and operating capability of the borrower/sponsor in its evaluation.
Deferred Financing Costs	Deferred Financing Costs Costs incurred in connection with debt financing are capitalized as a direct deduction from the carrying value of the debt, except for costs capitalized related to the Company’s unsecured credit facility, which are capitalized within the “Deferred costs, net” caption on the accompanying consolidated balance sheets. Deferred financing costs are charged to interest expense over the terms of the related debt agreements. Deferred financing costs consist primarily of loan fees which are amortized over the related loan term on a basis that approximates the effective interest method. Deferred financing costs are accelerated, when debt is extinguished, as part of the “Interest expense-amortization of deferred financing costs” caption within the Company’s consolidated statements of operations. Original issue discounts are recognized as part of the gain or loss on extinguishment of debt, as appropriate.
Revenue Recognition	Revenue Recognition Rental Revenue The Company generates revenue under leases with tenants occupying the Properties. Generally, leases with tenants are accounted for as operating leases. The operating leases have various expiration dates. As of December 31, 2023 and 2022, the Company did not have any leases classified as direct-financing or sales-type leases. Fixed lease payments under tenant leases, determined to be collectible, are recognized on a straight-line basis over the term of the related lease. The cumulative difference between lease revenue recognized under the straight-line method and contractual lease payments are recorded as “Accrued rent receivable” on the consolidated balance sheets. Variable lease payments are recognized as lease revenue in the period in which changes occur in facts and circumstances on which the variable lease payments are based. Topic 842 requires a binary approach to evaluating leases for collectability. Lessors are required to determine if it is probable that substantially all of the lease payments will be collected from the tenant over the lease term. Should the lessor determine that it is not probable that substantially all of the lease payments will be collected, the standard requires that the lessor write off any accrued rent receivable and begin recognizing lease payments on a cash basis. The Company’s lease revenue is impacted by the Company’s determination of whether improvements to the property, whether made by the Company or by the tenant, are landlord assets. The determination of whether an improvement is a landlord asset requires judgment. In making this judgment, the Company’s primary consideration is whether an improvement would be utilizable by another tenant upon the then-existing tenant vacating the improved space. If the Company has funded an improvement that it determines not to be landlord assets, then it treats the cost of the improvement as a lease incentive. If the tenant has funded an improvement that the Company determines to be landlord assets, then the Company treats the costs of the improvement as deferred revenue and amortizes these costs into revenue over the lease term. For certain leases, the Company also makes significant assumptions and judgments in determining the lease term, including assumptions when the lease provides the tenant with an early termination option or purchase option. The lease term impacts the period over which the Company determines and records lease payments and also impacts the period over which it amortizes lease-related costs. The Company considers all relevant factors that create an economic incentive for the lessee and uses judgment to determine if those factors, considered together, signify that the lessee is reasonably certain to exercise the option. For leases where a tenant executes a lease termination, termination fees are generally recognized over the modified term of the lease as rental income. Additionally, any deferred rents receivable are accelerated over the modified lease term. The Company’s leases also typically provide for tenant reimbursement of a portion of common area maintenance expenses and other operating expenses to the extent that a tenant’s pro rata share of expenses exceeds a base year level set in the lease or to the extent that the tenant has a lease on a triple net basis. As the timing and pattern of revenue recognition is the same, rents and tenant reimbursements are treated as a combined lease component and included in the “Rents” caption within the Company's consolidated statements of operations. Fixed lease payments include contractual rents under lease agreements with tenants recognized on a straight-line basis over the lease term, including amortization of lease incentives and above or below market rent intangibles, and parking income that is fixed under a long-term contract. Variable lease payments include reimbursements billed to tenants, termination fees, bad debt expense, and parking income that is not fixed under a long-term contract. Point of Sale Revenue Point of sale revenue consists of parking, restaurant, and flexible stay revenue from the Company’s hotel operations. Point of sale service obligations are performed daily, and the customer obtains control of those services simultaneously as they are performed. Accordingly, revenue is recorded on an accrual basis as it is earned, coinciding with the services that are provided to the Company’s customers. Parking and flexible stay revenue is recognized within rents and restaurant income is recognized within other income on the consolidated statements of operations. Third party management fees, labor reimbursement, and leasing The Company performs property management services for its managed real estate ventures and third-party property owners of real estate that consist of: (i) providing leasing services, (ii) property inspections, (iii) repairs and maintenance monitoring, and (iv) financial and accounting oversight. For these services, the Company earns management fees monthly, which are based on a fixed percentage of each managed property’s financial results, and is reimbursed for the labor costs incurred by its property management employees as services are rendered to the property owners. The Company determined that control over the services is passed to its customers simultaneously as performance occurs. Accordingly, management fee revenue is earned as the services are provided to the Company’s customers. Lease commissions are earned when the Company, as a broker for the third party property owner, executes a lease agreement with a tenant. Based on the terms of the Company’s lease commission contracts, the Company's performance obligation to the customer has been completed upon execution of each lease agreement. The Company’s lease commissions are earned based on a fixed percentage of rental income generated for each executed lease agreement and there is no variable income component. Development fee revenue is earned through two different sources: (i) the Company performs development services for third parties as an agent and earns fixed development fees based on a percentage of construction costs incurred over the construction period, and (ii) the Company acts as a general contractor on behalf of one of its managed real estate ventures. The Company acts as the principal construction company for the real estate ventures and records gross revenue as it provides construction services based on the quantifiable construction outputs. In applying the cost based output method of revenue recognition, the Company uses the actual costs incurred relative to the total estimated costs to determine its progress towards contract completion and to calculate the corresponding gross revenue and gross profit to recognize. For any costs that do not contribute to satisfying the Company’s performance obligations, it excludes such costs from its output methods of revenue recognition as the amounts are not reflective of transferring control of the outputs to the customer. The use of estimates in this calculation involves significant judgment. Common Development Cost Estimates for Contributions to Development Joint Ventures When land is contributed to a development joint venture, estimated common development costs include actual costs incurred and estimates of future common development costs benefiting the property sold. When land is sold, common development costs, if they cannot be specifically identified, are allocated to each sold parcel based upon its relative sales value. For purposes of allocating common development costs, estimates of future sales proceeds and common development costs are re-evaluated throughout the year, with adjustments being allocated prospectively to the remaining land parcels available for sale. The common development cost estimates for development joint ventures are highly judgmental as they are sensitive to cost escalation, sales price escalation and pace of absorption, which are subject to judgment and are affected by expectations about future market or economic conditions. Changes in the assumptions used to estimate future common development costs could result in a significant impact on the amounts recorded as net gain on disposition of real estate or net gain on sale of undepreciated real estate.
Income Taxes	Income Taxes Parent Company The Parent Company has elected to be treated as a REIT under Sections 856 through 860 of the Internal Revenue Code. In order to continue to qualify as a REIT, the Parent Company is required to, among other things, distribute at least 90% of its annual REIT taxable income to its shareholders and meet certain tests regarding the nature of its income and assets. As a REIT, the Parent Company is not subject to federal and state (in states that follow federal rules) income taxes with respect to the portion of its income that meets certain criteria and is distributed annually to its shareholders. Accordingly, a nominal provision for federal and state (as applicable) income taxes is included in the accompanying consolidated financial statements with respect to the operations of the Parent Company. The Parent Company intends to continue to operate in a manner that allows it to meet the requirements for taxation as a REIT. If the Parent Company fails to qualify as a REIT in any taxable year, it will be subject to federal and state (as applicable) income taxes and may not be able to qualify as a REIT for the four tax years following the year in which it first failed to qualify. The Parent Company is subject to certain local income taxes. Provision for federal income taxes is recorded in the income tax provision line item and state and local income taxes have been included in operating expenses in the Parent Company’s consolidated statements of operations. The Parent Company is subject to a 4% federal excise tax if sufficient taxable income is not distributed within prescribed time limits. The excise tax equals 4% of the annual amount, if any, by which the sum of (a) 85% of the Parent Company’s ordinary income and (b) 95% of the Parent Company’s net capital gain exceeds cash distributions and certain taxes paid by the Parent Company. No excise tax was incurred in 2023, 2022 or 2021. The Parent Company has elected to treat several of its subsidiaries as taxable REIT subsidiaries (each a “TRS”). A TRS is subject to federal, state and local income tax. In general, a TRS may perform non-customary services for tenants, hold assets that the Parent Company, as a REIT, cannot hold directly and generally may engage in any real estate or non-real estate related business. The Company’s taxable REIT subsidiaries did not have material tax provisions or deferred income tax items as of December 31, 2023 and December 31, 2022. Operating Partnership In general, the Operating Partnership is not subject to federal and state income taxes, and accordingly, no provision for income taxes has been made in the accompanying consolidated financial statements. The partners of the Operating Partnership are required to include their respective share of the Operating Partnership’s profits or losses in their respective tax returns. The Operating Partnership’s tax returns and the amount of allocable partnership profits and losses are subject to examination by federal and state taxing authorities. For any year beginning on or after January 1, 2017, the Operating Partnership can be assessed with federal income tax in the course of an audit by the IRS. Under the partnership audit rules included in the Bipartisan Budget Act of 2015, the Operating Partnership has the option to make a push-out election and allocate the partnership adjustments to all the former partners for the tax year under audit. The Operating Partnership may elect to treat a subsidiary as a REIT under Sections 856 through 860 of the Internal Revenue Code, if applicable. Each subsidiary REIT would be required to meet the requirements for treatment as a REIT under Sections 856 through 860 of the Internal Revenue Code. If a subsidiary REIT fails to qualify as a REIT in any taxable year, that subsidiary REIT would be subject to federal and state income taxes and would not be able to qualify as a REIT for the four subsequent taxable years. Also, each subsidiary REIT would be subject to certain local income taxes. The Operating Partnership has elected to treat several of its subsidiaries as TRSs, which are subject to federal, state and local income tax.
Earnings Per Share and Per Unit	Earnings Per Share Basic earnings per share (“EPS”) is computed by dividing net income available to common shareholders, as adjusted for unallocated earnings, if any, of certain securities, by the weighted average number of common shares outstanding during the year. Diluted EPS reflects the potential dilution that could occur from common shares issuable in connection with awards under share-based compensation plans, including upon the exercise of stock options, and conversion of the noncontrolling interests in the Operating Partnership. Anti-dilutive shares are excluded from the calculation. Earnings Per Unit Basic earnings per unit is computed by dividing net income available to common unitholders, as adjusted for unallocated earnings, if any, of certain securities issued by the Operating Partnership, by the weighted average number of common unit equivalents outstanding during the year. Diluted earnings per unit reflects the potential dilution that could occur from units issuable in connection with awards under share-based compensation plans, including upon the exercise of stock options. Anti-dilutive units are excluded from the calculation.
Share-Based Compensation Plans	Share-Based Compensation Plans
Comprehensive Income	Comprehensive Income Comprehensive income is recorded in accordance with the provisions of the accounting standard for comprehensive income. The accounting standard establishes standards for reporting comprehensive income and its components in the financial statements. Comprehensive income includes the effective portions of changes in the fair value of derivatives.
Accounting for Derivative Instruments and Hedging Activities	Accounting for Derivative Instruments and Hedging Activities The Company accounts for its derivative instruments and hedging activities in accordance with the accounting standard for derivative and hedging activities. The accounting standard requires the Company to measure every derivative instrument (including certain derivative instruments embedded in other contracts) at fair value and record them on the balance sheet as either an asset or liability. See disclosures below related to the accounting standard for fair value measurements and disclosures. For derivatives designated as cash flow hedges, the effective portions of changes in the fair value of the derivative are reported in other comprehensive income while the ineffective portions are recognized in earnings. The Company actively manages its ratio of fixed-to-floating rate debt. To manage its fixed and floating rate debt in a cost-effective manner, the Company, from time to time, enters into interest rate swap agreements as cash flow hedges, under which it agrees to exchange various combinations of fixed and/or variable interest rates based on agreed upon notional amounts.
Fair Value Measurements	Fair Value Measurements The Company estimates the fair value of its derivatives in accordance with the accounting standard for fair value measurements and disclosures. The accounting standard defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. It also establishes a fair value hierarchy which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The standard describes three levels of inputs that may be used to measure fair value. 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. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability. Non-financial assets and liabilities recorded at fair value on a non-recurring basis include non-financial assets and liabilities measured at fair value in a purchase price allocation and the impairment. The fair values assigned to the Company's purchase price allocations primarily utilize Level 3 inputs. The fair value assigned to the long-lived assets and equity method investments for which there was impairment recorded utilize Level 3 inputs
Recent Accounting Pronouncements	Recent Accounting Pronouncements In March 2020, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (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, 2024. The guidance may be elected over time as reference rate reform activities occur. The implementation of this standard did not have a material impact on the Company. During the second quarter of 2022, the Company elected to apply the hedge accounting expedients related to probability and the assessments of effectiveness for future LIBOR-indexed cash flows to assume that the index upon which future hedged transactions will be based matches the index on the corresponding derivatives. In addition, the Company elected to apply the hedge accounting expedients related to changes in critical terms of derivative or hedged transactions, and bilaterally negotiated contract changes for the refinance of the Company's term loan and associated interest rate swap. The Company continues to evaluate the impact of the guidance and may apply elections as applicable as additional changes in the market occur. See Note 9, “Debt Obligations” for further information regarding our remaining LIBOR-indexed obligations. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280). The new standard requires enhanced disclosures about significant segment expenses and other segment items and requires companies to disclose all annual disclosures about segments in interim periods. The new standard also permits companies to disclose more than one measure of segment profit or loss, requires disclosure of the title and position of the Chief Operating Decision Maker, and requires companies with a single reportable segment to provide all disclosures required by Topic 280. The new standard is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted and companies are required to apply the ASU retrospectively to all periods presented. The Company is currently evaluating the impact that the adoption of this standard will have on its financial statements and related disclosures.

ORGANIZATION OF THE PARENT CO_2

ORGANIZATION OF THE PARENT COMPANY AND THE OPERATING PARTNERSHIP (Tables)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule 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 December 31, 2023: Number of Properties Rentable Square Feet Office properties 65 11,773,665 Mixed-use properties 4 924,450 Core Properties 69 12,698,115 Development property 2 144,685 Recently completed - not stabilized property 1 168,294 The Properties 72 13,011,094

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Schedule of Disaggregation of Revenue	The following is a summary of revenue earned by the Company’s reportable segments (see Note 19 “Segment Information,” for further information) during the year ended December 31, 2023 (in thousands): Philadelphia CBD Pennsylvania Suburbs Austin, Texas Other Corporate (a) Total Fixed rent $ 159,732 $ 118,856 $ 63,209 $ 32,167 $ (1,895) $ 372,069 Variable rent 54,678 10,067 30,098 1,681 454 96,978 Total lease revenue 214,410 128,923 93,307 33,848 (1,441) 469,047 Amortization of deferred market rents 649 — 642 — — 1,291 Daily parking & hotel flexible stay 8,478 — 708 325 — 9,511 Total rents 223,537 128,923 94,657 34,173 (1,441) 479,849 Third party management fees, labor reimbursement and leasing 405 38 516 4,972 18,486 24,417 Other income 6,991 339 332 161 2,562 10,385 Total revenue $ 230,933 $ 129,300 $ 95,505 $ 39,306 $ 19,607 $ 514,651 (a) Corporate includes intercompany eliminations necessary to reconcile to consolidated Company totals. The following is a summary of revenue earned by the Company’s reportable segments (see Note 19 “Segment Information,” for further information) during the year ended December 31, 2022 (in thousands): Philadelphia CBD Pennsylvania Suburbs Austin, Texas Other Corporate (a) Total Fixed rent $ 151,034 $ 116,926 $ 60,831 $ 26,491 $ (1,895) $ 353,387 Variable rent 51,346 11,615 32,958 3,927 (35) 99,811 Total lease revenue 202,380 128,541 93,789 30,418 (1,930) 453,198 Amortization of deferred market rents 1,308 10 1,264 — — 2,582 Daily parking & hotel flexible stay 14,390 — 361 320 — 15,071 Total rents 218,078 128,551 95,414 30,738 (1,930) 470,851 Third party management fees, labor reimbursement and leasing 287 35 486 5,711 17,613 24,132 Other income 2,510 354 429 161 7,663 11,117 Total revenue $ 220,875 $ 128,940 $ 96,329 $ 36,610 $ 23,346 $ 506,100 (a) Corporate includes intercompany eliminations necessary to reconcile to consolidated Company totals. The following is a summary of revenue earned by the Company’s reportable segments (see Note 19 “Segment Information,” for further information) during the year ended December 31, 2021 (in thousands): Philadelphia CBD Pennsylvania Suburbs Austin, Texas Other Corporate (a) Total Fixed rent $ 149,441 $ 113,748 $ 62,545 $ 20,430 $ (2,240) $ 343,924 Variable rent 41,585 10,358 34,850 3,306 (257) 89,842 Total lease revenue 191,026 124,106 97,395 23,736 (2,497) 433,766 Amortization of deferred market rents 2,064 (9) 3,322 — — 5,377 Daily parking & hotel flexible stay 11,758 159 109 350 — 12,376 Total rents 204,848 124,256 100,826 24,086 (2,497) 451,519 Third party management fees, labor reimbursement and leasing 893 34 452 9,625 15,440 26,444 Other income 2,117 276 402 169 5,892 8,856 Total revenue $ 207,858 $ 124,566 $ 101,680 $ 33,880 $ 18,835 $ 486,819 (a) Corporate includes intercompany eliminations necessary to reconcile to consolidated Company totals.

REAL ESTATE INVESTMENTS (Tables

REAL ESTATE INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
Real Estate [Abstract]
Schedule of Gross Carrying Value of Operating Properties	As of December 31, 2023 and 2022, the gross carrying value of the operating properties was as follows (in thousands): December 31, 2023 December 31, 2022 Land $ 394,669 $ 403,998 Building and improvements 2,671,024 2,760,357 Tenant improvements 476,539 452,885 Total $ 3,542,232 $ 3,617,240
Schedule of Capitalized Construction Costs	The following table shows the amount of compensation costs (including bonuses and benefits) capitalized for the years presented (in thousands): December 31, 2023 2022 2021 Development $ 4,096 $ 5,343 $ 4,815 Redevelopment 944 1,484 1,170 Tenant Improvements 3,817 2,505 1,917 Total $ 8,857 $ 9,332 $ 7,902
Schedule of Acquired Properties	Property/Portfolio Name Acquisition Date Location Property Type Rentable Square Feet/Acres Purchase Price 165 King of Prussia Road October 27, 2023 Radnor, PA Land 1.1 acres $ 8,550 Property/Portfolio Name Acquisition Date Location Property Type Rentable Square Feet/Acres Purchase Price 631 Park Avenue January 21, 2022 King of Prussia, PA Land 3.3 acres $ 3,650 3151 Market Street (a) April 29, 2022 Philadelphia, PA Leasehold Interest 0.8 acres $ 27,349 (a) On April 29, 2022, the Company acquired, through a 99-year ground lease, the leasehold interest in a 0.8-acre land parcel, located at 3151 Market Street, in Philadelphia, Pennsylvania. The Company prepaid $19.5 million of the ground lease, representing 500,000 square feet of buildable floor to area ratio (“FAR”) to be used for the development of 3151 Market Street, and paid $7.8 million for 200,000 square feet of FAR density usable pursuant to the Schuylkill Yards Project master development agreement. The additional density is included in prepaid leasehold interests in land held for development in the consolidated balance sheets. See below regarding disposition of 500,000 square feet of FAR.
Schedule of Office Properties Sold	The following table summarizes the property dispositions during the years ended December 31, 2023, 2022 and 2021 (dollars in thousands): Property/Portfolio Name Disposition Date Location Property Type Rentable Square Feet/Acres Sales Price Gain/(Loss) on Sale (a) Dabney East December 27, 2023 Richmond, VA Land 11.6 acres $ 1,600 $ 430 Byberry December 7, 2023 Philadelphia, PA Land Purchase Option 50.0 acres $ 9,641 $ 3,960 8521 Leesburg Pike (f) December 1, 2023 Vienna, VA Office 150,897 $ 11,000 $ — 200 N. Radnor Chester Road October 31, 2023 Radnor, PA Retail 17,884 $ 14,200 $ 7,735 Three Barton Skyway (f) August 4, 2023 Austin, TX Office 173,302 $ 53,250 $ — 200 Barr Harbor Drive November 22, 2022 West Conshohocken, PA Office 86,000 $ 30,500 $ 8,740 11501 Burnett Road (d) July 29, 2022 Austin, TX Land 4.7 acres $ 32,513 $ 8,340 3151 Market Street (c) July 14, 2022 Philadelphia, PA Leasehold Interest 0.8 acres $ 30,394 $ 2,583 Gibbsboro Portfolio (b) June 28, 2022 Gibbsboro, NJ Office/Land 42,809/4.0 acres $ 4,100 $ 831 25 M Street (e) April 14, 2022 Washington, D.C. Land 0.8 acres $ 29,675 $ 3,836 Gateway G & H January 20, 2022 Richmond, VA Land 10.0 acres $ 1,600 $ 897 1100 Lenox Drive September 8, 2021 Lawrenceville, NJ Land 5.0 acres $ 2,575 $ 68 2100-2200 Lenox Drive July 6, 2021 Lawrenceville, NJ Land 35.2 acres $ 8,900 $ 842 3025 JFK Boulevard February 2, 2021 Philadelphia, PA Leasehold Interest 1.0 acres $ 34,800 $ 2,000 (a) Gain/(Loss) on Sale is net of closing and other transaction related costs. (b) Includes $0.7 million of gain on sale of undepreciated real estate and $0.1 million of gain on disposition of real estate included within the consolidated statements of operations for the twelve months ended December 31, 2022. (c) On July 14, 2022, the Company contributed 500,000 square feet of FAR relating to its 99-year prepaid leasehold interest at 3151 Market Street in Philadelphia, Pennsylvania, acquired on April 29, 2022, to a newly formed joint venture with an unaffiliated third party. The Company's initial deemed contribution in the project was $30.4 million and the transaction resulted in deconsolidation of the property and conversion of Brandywine 3151 Market, LP, (formerly a wholly-owned subsidiary of the Operating Partnership) to a real estate venture (“3151 Market Street Venture”). The Company recorded its investment at fair value and recognized a gain, net of transaction costs, of $2.6 million, in “Net gain on sale of undepreciated real estate” on the consolidated statements of operations. See Note 4, “Investment in Unconsolidated Real Estate Ventures,” for further information. (d) On July 29, 2022, the Company contributed a 4.7 acre parcel of land held for development at 11501 Burnet Road in Austin, Texas to a newly formed joint venture with an unaffiliated third party. The project is part of the Uptown ATX master development. The Company's combined contributed initial land investment in the project was $32.5 million and the transaction resulted in the deconsolidation of the property and formation of Brandywine Uptown Office LLC and Brandywine One Uptown Multifamily LLC, (together, “One Uptown Ventures)”). The Company recorded its investment at fair value and recognized a gain of $8.3 million in “Net gain on disposition of real estate” on the consolidated statements of operations. Gain on sale of $8.3 million is calculated as the difference between the estimated relative sales value of the contributed land and the estimated total cost allocations per block. See Note 4, “Investment in Unconsolidated Real Estate Ventures,” for further information. (e) On September 30, 2022, the Company recognized $0.4 million of additional gain on disposition of real estate. (f) Recognized a provision for impairment of $16.7 million on the property prior to the sales.

INVESTMENT IN UNCONSOLIDATED _2

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES (Tables)	12 Months Ended
	Dec. 31, 2023
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Financial Position of Real Estate Ventures	The Company’s investment in the unconsolidated real estate ventures as of December 31, 2023 and 2022, and the Company’s share of the unconsolidated real estate ventures’ income (loss) for the years ended December 31, 2023, 2022, and 2021 was as follows (in thousands): Ownership Percentage Carrying Amount Company's unconsolidated real estate venture Income (Loss) Unconsolidated Real Estate Venture Debt at 100%, gross 2023 2022 2023 2022 2021 2023 2022 Office Properties Commerce Square Venture 78% (a) $ 272,216 $ 238,105 $ (18,791) $ (12,128) $ (15,501) $ 220,000 $ 206,737 Mid-Atlantic Office Venture (e) 40% (a) — 31,005 (26,448) 412 932 132,770 128,904 Herndon Innovation Center Metro Portfolio Venture, LLC 15% 3,518 15,304 (11,854) (536) (174) 233,443 207,302 MAP Venture (b) 50% (48,733) (35,411) (10,580) (8,340) (8,683) 179,842 182,053 Cira Square 20% 25,242 27,815 (2,474) (985) — 257,700 257,700 Other 4040 Wilson Venture (c) 50% 29,419 29,633 (2,536) (1,211) (2,258) 145,000 145,070 1919 Venture (d) 50% — — — 1,392 427 — — Brandywine - AI Venture LLC 50% — — — — (721) — — Development Properties 3025 JFK Venture (c) 58% 62,034 57,630 (4,456) (35) (118) 152,032 60,118 JBG - 51 N Street (c) 70% 21,150 21,208 (435) (382) (402) — — JBG - 1250 First Street Office (c) 70% 17,843 17,759 (269) (195) (199) — — 3151 Market Street Venture (c) 64% 90,645 63,751 (72) (8) — — — One Uptown - Office (c) 57% 47,036 34,980 — — — 51,701 16,895 One Uptown - Multifamily (c) 50% 32,124 30,445 — — — 40,270 — $ 552,494 $ 532,224 $ (77,915) $ (22,016) $ (26,697) $ 1,412,758 $ 1,204,779 (a) Ownership percentage represents the Company’s combined interest including preferred and common equity holdings. See “Commerce Square Venture” and “Mid-Atlantic Office JV” sections below for more information. (b) Included within “Other Liabilities” on the consolidated balance sheet. (c) This entity is a VIE. (d) On November 30, 2022, the Company sold its interest in 1919 Venture. See “1919 Venture” sections for more information on the disposal. (e) On January 9, 2024 the real estate venture’s secured mortgage loan matured. The real estate venture is in active discussions, including with the mortgage lender, as to a potential extension of the loan or other restructuring of the venture. The following is a summary of the financial position of the unconsolidated real estate ventures in which the Company held interests as of December 31, 2023 and December 31, 2022 (in thousands): December 31, 2023 December 31, 2022 Net property $ 2,339,921 $ 2,117,226 Other assets 534,658 506,213 Other liabilities 443,536 446,101 Debt, net 1,407,858 1,198,213 Equity (a) 1,023,185 979,125 (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.
Schedule of Results of Operations of Real Estate Ventures with Interests	The following is a summary of results of operations of the unconsolidated real estate ventures in which the Company held interests during the twelve-month periods ended December 31, 2023, 2022 and 2021 (in thousands): Year Ended December 31, 2023 2022 2021 Revenue $ 232,895 $ 244,981 $ 214,792 Operating expenses (122,181) (124,608) (117,273) Interest expense, net (78,909) (49,007) (30,569) Depreciation and amortization (100,205) (103,378) (97,147) Provision for impairment — — (1,393) Net loss $ (68,400) $ (32,012) $ (31,590) Ownership interest % Various Various Various Company's share of net loss $ (39,637) $ (21,594) $ (25,972) Other-than-temporary impairment (a) (37,176) — — Basis adjustments and other (1,102) (422) (725) Equity in loss of unconsolidated real estate ventures $ (77,915) $ (22,016) $ (26,697) (a)
Schedule of Maturities of Long-term Debt	As of December 31, 2023, the aggregate principal payments of the unconsolidated real estate ventures recourse and non-recourse debt payable to third-parties are as follows (in thousands): 2024 $ 803,756 2025 152,032 2026 236,971 2027 — 2028 220,000 Thereafter — Total principal payments 1,412,759 Net deferred financing costs (4,901) Outstanding indebtedness $ 1,407,858 As of December 31, 2023, the aggregate scheduled principal payments on the Company's debt obligations were as follows (in thousands): 2024 $ 340,000 2025 70,000 2026 13,824 2027 700,000 2028 595,000 Thereafter 428,610 Total principal payments 2,147,434 Net unamortized premiums/(discounts) 1,878 Net deferred financing costs (10,480) Outstanding indebtedness $ 2,138,832

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Schedule of Operating Lease Future Contractual Lease Payments	The Company leases properties to tenants under operating leases with various expiration dates. Future contractual lease payments under operating leases at December 31, 2023 are as follows (in thousands): Year 2024 $ 348,890 2025 344,575 2026 329,584 2027 294,997 2028 262,816 Thereafter 944,863
Schedule of Lease Costs	The table below summarizes the Company’s operating lease cost (in thousands) recognized through “Property operating expenses” on the consolidated statements of operations (in thousands): Year Ended December 31, Lease Cost 2023 2022 Fixed lease cost $ 2,100 $ 2,100 Variable lease cost 57 67 Total $ 2,157 $ 2,167 Weighted-average remaining lease term (years) 54.0 54.6 Weighted-average discount rate 6.3 % 6.3 %
Schedule of Operating Lease Liability Maturities	Lease payments on noncancellable leases at December 31, 2023 are as follows (in thousands): Year Minimum Rent 2024 $ 1,305 2025 1,321 2026 1,338 2027 1,355 2028 1,373 Thereafter 105,065 Total lease payments $ 111,757 Less: Imputed interest 88,388 Present value of operating lease liabilities $ 23,369

DEFERRED COSTS (Tables)

DEFERRED COSTS (Tables)	12 Months Ended
	Dec. 31, 2023
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Deferred Costs	As of December 31, 2023 and 2022, the Company’s deferred costs were comprised of the following (in thousands): December 31, 2023 Total Cost Accumulated Amortization Deferred Costs, net Leasing costs $ 164,274 $ (71,220) $ 93,054 Financing costs - Unsecured Credit Facility 4,688 (1,758) 2,930 Total $ 168,962 $ (72,978) $ 95,984 December 31, 2022 Total Cost Accumulated Amortization Deferred Costs, net Leasing costs $ 155,457 $ (62,920) $ 92,537 Financing costs - Unsecured Credit Facility 4,688 (586) 4,102 Total $ 160,145 $ (63,506) $ 96,639

INTANGIBLE ASSETS AND LIABILI_2

INTANGIBLE ASSETS AND LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets and Liabilities	As of December 31, 2023 and 2022, the Company’s intangible assets/liabilities were comprised of the following (in thousands): December 31, 2023 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 24,281 $ (16,673) $ 7,608 Tenant relationship value 110 (52) 58 Above market leases acquired 75 (47) 28 Total intangible assets, net $ 24,466 $ (16,772) $ 7,694 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 17,588 $ (9,318) $ 8,270 December 31, 2022 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 55,715 $ (37,437) $ 18,278 Tenant relationship value 167 (104) 63 Above market leases acquired 331 (221) 110 Total intangible assets, net $ 56,213 $ (37,762) $ 18,451 Total Cost Accumulated Amortization Intangible Liabilities, net Intangible liabilities, net: Below market leases acquired $ 20,985 $ (10,663) $ 10,322
Schedule of Amortization for Intangible Assets and Liabilities	As of December 31, 2023, the Company’s annual amortization for its intangible assets/liabilities, assuming no prospective early lease terminations, was as follows (dollars in thousands): Assets Liabilities 2024 $ 1,818 $ 929 2025 1,485 869 2026 1,093 739 2027 808 623 2028 313 534 Thereafter 2,177 4,576 Total $ 7,694 $ 8,270

DEBT OBLIGATIONS (Tables)

DEBT OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule of Consolidated Debt Obligations	The following table sets forth information regarding the Company’s consolidated debt obligations outstanding as of December 31, 2023 and 2022 (in thousands): December 31, 2023 December 31, 2022 Effective Maturity SECURED DEBT $245.0M 5.88% Secured Term Loan due 2028 $ 245,000 $ — 5.88% February 2028 $50.0M Construction Loan due 2026 13,824 — SOFR + 2.50% August 2026 Principal balance outstanding 258,824 — Less: deferred financing costs (3,153) — Total Secured indebtedness $ 255,671 $ — UNSECURED DEBT $600 million Unsecured Credit Facility $ — $ 88,500 SOFR + 1.15% June 2026 (a) Term Loan - Swapped to fixed 250,000 250,000 SOFR + 1.30% June 2027 (b) $70.0 million Term Loan 70,000 — SOFR + 1.85% February 2024 (a)(c) $350.0M 3.95% Guaranteed Notes due 2023 — 54,301 3.87% February 2023 (d) $350.0M 4.10% Guaranteed Notes due 2024 (e) 340,000 350,000 3.78% October 2024 $450.0M 3.95% Guaranteed Notes due 2027 450,000 450,000 4.03% November 2027 $350.0M 7.55% Guaranteed Notes due 2028 350,000 350,000 7.98% (f) March 2028 $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 SOFR + 1.51% (g) March 2035 Indenture IB (Preferred Trust I) 25,774 25,774 SOFR + 1.51% (g) April 2035 Indenture II (Preferred Trust II) 25,774 25,774 SOFR + 1.51% (g) July 2035 Principal balance outstanding 1,888,610 1,971,411 Plus: original issue premium (discount), net 1,878 2,934 Less: deferred financing costs (7,327) (9,307) Total unsecured indebtedness $ 1,883,161 $ 1,965,038 (a) Spread includes a 10 basis point daily SOFR adjustment. (b) On November 23, 2022, the unsecured term loan of $250.0 million was swapped to a fixed rate of 5.01% and matures on June 30, 2027. The effective date of the swap is January 31, 2023. (c) The maturity date of the Unsecured Term Loan is subject to a 12 month optional extension. The Company executed the 12 month extension through February 2025 . (d) On January 20, 2023, the Company redeemed in full its then outstanding 3.95% Guaranteed Notes due 2023 (the “ 2023 Notes ” ). The redemption price of the 2023 Notes was approximately $55.2 (approximately $54.3 million in principal and approximately $0.92 million of accrued and unpaid interest). (e) On December 22, 2023, the Company repurchased $10.0 million of its outstanding $350 million Notes due 2023 ahead of its scheduled maturity at a price of 98.6% and paid accrued interest of $0.1 million. As a result of the repurchase the Company recorded a gain from the early extinguishment of debt of $0.1 million. (f) The note includes an interest rate adjustment provision whereby the interest rate payable on the notes is subject to an 25 basis point adjustment if either Moody's or S&P downgrades (or subsequently upgrades) its rating assigned to the 2028 Notes. During the third quarter of 2023, Moody’s downgraded our senior unsecured credit rating from Baa3 to Ba1. As a result of the downgrade, the interest rate on our 2028 Notes increased 25 basis points in September 2023 to 7.80%. Subsequent to December 31, 2023, S&P downgraded our senior unsecured credit rating from BBB- to BB+. As a result of the downgrade, the interest rate will increase 25 basis points in March 2024 to 8.05%. (g) On January 16, 2024, the Trust Preferred I - Indenture IA was swapped to a fixed rate at 5.14% for the period from March 30, 2024 to December 30, 2026 and Trust Preferred I - Indenture IB and Trust Preferred II - Indenture II were swapped to a fixed rate at 5.24% for the period from January 30, 2024 to January 30, 2027.
Schedule of Maturities of Long-term Debt	As of December 31, 2023, the aggregate principal payments of the unconsolidated real estate ventures recourse and non-recourse debt payable to third-parties are as follows (in thousands): 2024 $ 803,756 2025 152,032 2026 236,971 2027 — 2028 220,000 Thereafter — Total principal payments 1,412,759 Net deferred financing costs (4,901) Outstanding indebtedness $ 1,407,858 As of December 31, 2023, the aggregate scheduled principal payments on the Company's debt obligations were as follows (in thousands): 2024 $ 340,000 2025 70,000 2026 13,824 2027 700,000 2028 595,000 Thereafter 428,610 Total principal payments 2,147,434 Net unamortized premiums/(discounts) 1,878 Net deferred financing costs (10,480) Outstanding indebtedness $ 2,138,832

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
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): December 31, 2023 December 31, 2022 Carrying Amount (a) Fair Value Carrying Amount (a) Fair Value Unsecured notes payable $ 1,486,052 $ 1,386,621 $ 1,549,760 $ 1,411,351 Variable rate debt $ 410,932 $ 370,665 $ 415,278 $ 386,988 Secured fix rate debt $ 241,847 $ 233,088 $ — $ — (a) Net of deferred financing costs of $5.8 million and $7.5 million for unsecured notes payable, $1.5 million and $1.8 million for variable rate debt and $3.2 million and $0.0 million for secured fix rate debt as of December 31, 2023 and December 31, 2022, respectively

DERIVATIVE FINANCIAL INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
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 December 31, 2023 and December 31, 2022. 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 12/31/2023 12/31/2022 12/31/2023 12/31/2022 Assets Swap Interest Rate Cash Flow (a) $ 250,000 $ — 3.729 % November 23, 2022 June 30, 2027 $ — $ 255 Liabilities Swap Interest Rate Cash Flow (a) $ — $ 250,000 3.729 % November 23, 2022 June 30, 2027 $ (757) $ — $ 250,000 $ 250,000 (a) Hedging unsecured variable rate debt.

BENEFICIARIES' EQUITY OF THE _2

BENEFICIARIES' EQUITY OF THE PARENT COMPANY (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Earnings Per Share, 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): Year Ended December 31, 2023 2022 2021 Basic Diluted Basic Diluted Basic Diluted Numerator Net income (loss) $ (197,403) $ (197,403) $ 53,992 $ 53,992 $ 12,366 $ 12,366 Net (income) loss attributable to noncontrolling interests 614 614 (168) (168) (77) (77) Nonforfeitable dividends allocated to unvested restricted shareholders (567) (567) (456) (456) (421) (421) Net income (loss) attributable to common shareholders $ (197,356) $ (197,356) $ 53,368 $ 53,368 $ 11,868 $ 11,868 Denominator Weighted-average shares outstanding 171,959,210 171,959,210 171,491,369 171,491,369 170,878,185 170,878,185 Contingent securities/Share-based compensation — — — 834,277 — 1,395,055 Weighted-average shares outstanding 171,959,210 171,959,210 171,491,369 172,325,646 170,878,185 172,273,240 Earnings (loss) per Common Share: Net income (loss) attributable to common shareholders $ (1.15) $ (1.15) $ 0.31 $ 0.31 $ 0.07 $ 0.07 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): Year Ended December 31, 2023 2022 2021 Basic Diluted Basic Diluted Basic Diluted Numerator Net income (loss) $ (197,403) $ (197,403) $ 53,992 $ 53,992 $ 12,366 $ 12,366 Net loss attributable to noncontrolling interests 22 22 2 2 3 3 Nonforfeitable dividends allocated to unvested restricted unitholders (567) (567) (456) (456) (421) (421) Net income (loss) attributable to common unitholders $ (197,948) $ (197,948) $ 53,538 $ 53,538 $ 11,948 $ 11,948 Denominator Weighted-average units outstanding 172,475,645 172,475,645 172,036,481 172,036,481 171,770,843 171,770,843 Contingent securities/Share-based compensation — — — 834,277 — 1,395,055 Total weighted-average units outstanding 172,475,645 172,475,645 172,036,481 172,870,758 171,770,843 173,165,898 Earnings (loss) per Common Partnership Unit: Net income (loss) attributable to common unitholders $ (1.15) $ (1.15) $ 0.31 $ 0.31 $ 0.07 $ 0.07

PARTNERS' EQUITY OF THE PAREN_2

PARTNERS' EQUITY OF THE PARENT COMPANY (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Earnings Per Share, 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): Year Ended December 31, 2023 2022 2021 Basic Diluted Basic Diluted Basic Diluted Numerator Net income (loss) $ (197,403) $ (197,403) $ 53,992 $ 53,992 $ 12,366 $ 12,366 Net (income) loss attributable to noncontrolling interests 614 614 (168) (168) (77) (77) Nonforfeitable dividends allocated to unvested restricted shareholders (567) (567) (456) (456) (421) (421) Net income (loss) attributable to common shareholders $ (197,356) $ (197,356) $ 53,368 $ 53,368 $ 11,868 $ 11,868 Denominator Weighted-average shares outstanding 171,959,210 171,959,210 171,491,369 171,491,369 170,878,185 170,878,185 Contingent securities/Share-based compensation — — — 834,277 — 1,395,055 Weighted-average shares outstanding 171,959,210 171,959,210 171,491,369 172,325,646 170,878,185 172,273,240 Earnings (loss) per Common Share: Net income (loss) attributable to common shareholders $ (1.15) $ (1.15) $ 0.31 $ 0.31 $ 0.07 $ 0.07 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): Year Ended December 31, 2023 2022 2021 Basic Diluted Basic Diluted Basic Diluted Numerator Net income (loss) $ (197,403) $ (197,403) $ 53,992 $ 53,992 $ 12,366 $ 12,366 Net loss attributable to noncontrolling interests 22 22 2 2 3 3 Nonforfeitable dividends allocated to unvested restricted unitholders (567) (567) (456) (456) (421) (421) Net income (loss) attributable to common unitholders $ (197,948) $ (197,948) $ 53,538 $ 53,538 $ 11,948 $ 11,948 Denominator Weighted-average units outstanding 172,475,645 172,475,645 172,036,481 172,036,481 171,770,843 171,770,843 Contingent securities/Share-based compensation — — — 834,277 — 1,395,055 Total weighted-average units outstanding 172,475,645 172,475,645 172,036,481 172,870,758 171,770,843 173,165,898 Earnings (loss) per Common Partnership Unit: Net income (loss) attributable to common unitholders $ (1.15) $ (1.15) $ 0.31 $ 0.31 $ 0.07 $ 0.07

SHARE-BASED COMPENSATION, 401_2

SHARE-BASED COMPENSATION, 401(K) PLAN AND DEFERRED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Company's Restricted Share Activity	The following table summarizes the Company’s Restricted Share Rights activity during the year-ended December 31, 2023: Shares Weighted Average Grant Date Fair Value Non-vested at January 1, 2023 553,893 $ 13.22 Granted 808,283 $ 6.03 Vested (458,111) $ 9.29 Forfeited (14,899) $ 8.61 Non-vested at December 31, 2023 889,166 $ 8.79
Schedule of Restricted Performance Share Units Plan	The table below presents certain information as to unvested RPSU awards. RPSU Grant Date 3/5/2021 3/3/2022 2/16/2023 Total (Amounts below in shares, unless otherwise noted) Non-vested at January 1, 2023 371,239 513,038 — 884,277 Granted — — 1,057,173 1,057,173 Units Cancelled — — — — Non-vested at December 31, 2023 371,239 513,038 1,057,173 1,941,450 Measurement Period Commencement Date 1/1/2021 1/1/2022 1/1/2023 Measurement Period End Date 12/31/2023 12/31/2024 12/31/2025 Granted 380,957 516,852 1,057,173 Fair Value of Units on Grant Date (in thousands) $ 6,389 $ 6,872 $ 7,125

DISTRIBUTIONS (Tables)

DISTRIBUTIONS (Tables)	12 Months Ended
	Dec. 31, 2023
Distributions [Abstract]
Schedule of Dividends Payable	The following table provides the tax characteristics of the 2023, 2022 and 2021 distributions paid: Years ended December 31, 2023 2022 2021 (in thousands, except per share amounts) Common Share Distributions: Ordinary income $ 0.39 $ 0.47 $ 0.64 Capital gain 0.03 0.29 0.01 Non-taxable distributions 0.30 — 0.11 Distributions per share $ 0.72 $ 0.76 $ 0.76 Percentage classified as ordinary income 54.40 % 62.10 % 83.90 % Percentage classified as capital gain 4.00 % 37.90 % 1.20 % Percentage classified as non-taxable distribution 41.60 % — % 14.90 %

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table details the components of accumulated other comprehensive income (loss) of the Parent Company and the Operating Partnership as of and for the three years ended December 31, 2023 (in thousands): Parent Company Cash Flow Hedges Balance at January 1, 2021 $ (7,561) Change in fair market value during year 4,817 Allocation of unrealized (gains)/losses on derivative financial instruments to noncontrolling interests (28) Amortization of interest rate contracts reclassified from comprehensive income to interest expense 752 Balance at December 31, 2021 $ (2,020) Change in fair market value during year 5,371 Allocation of unrealized (gains)/losses on derivative financial instruments to noncontrolling interests (18) Amortization of interest rate contracts reclassified from comprehensive income to interest expense 564 Balance at December 31, 2022 $ 3,897 Change in fair market value during year (4,579) Allocation of unrealized (gains)/losses on derivative financial instruments to noncontrolling interests 14 Amortization of interest rate contracts reclassified from comprehensive income to interest expense — Balance at December 31, 2023 $ (668) Operating Partnership Cash Flow Hedges Balance at January 1, 2021 $ (7,935) Change in fair market value during year 4,817 Amortization of interest rate contracts reclassified from comprehensive income to interest expense 752 Balance at December 31, 2021 $ (2,366) Change in fair market value during year 5,371 Amortization of interest rate contracts reclassified from comprehensive income to interest expense 564 Balance at December 31, 2022 $ 3,569 Change in fair market value during year (4,579) Amortization of interest rate contracts reclassified from comprehensive income to interest expense — Balance at December 31, 2023 $ (1,010)

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Schedule of 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: December 31, 2023 December 31, 2022 Philadelphia CBD $ 1,534,893 $ 1,517,801 Pennsylvania Suburbs 900,230 878,546 Austin, Texas 801,973 851,835 Total Core Segments 3,237,096 3,248,182 Other 305,136 369,058 Operating Properties $ 3,542,232 $ 3,617,240 Corporate Right of use asset - operating leases, net $ 19,031 $ 19,664 Construction-in-progress $ 135,529 $ 218,869 Land held for development $ 82,510 $ 76,499 Prepaid leasehold interests in land held for development, net $ 27,762 $ 35,576 . Net operating income: Year Ended December 31, 2023 2022 2021 Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income Philadelphia CBD $ 230,933 $ (79,579) $ 151,354 $ 220,876 $ (79,827) $ 141,049 $ 207,858 $ (73,695) $ 134,163 Pennsylvania Suburbs 129,300 (39,584) 89,716 128,940 (41,814) 87,126 124,566 (40,011) 84,555 Austin, Texas 95,505 (38,453) 57,052 96,328 (41,141) 55,187 101,680 (39,374) 62,306 Other 39,306 (21,134) 18,172 36,610 (21,165) 15,445 33,880 (25,226) 8,654 Corporate 19,607 (11,197) 8,410 23,346 (10,454) 12,892 18,835 (10,005) 8,830 Operating properties $ 514,651 $ (189,947) $ 324,704 $ 506,100 $ (194,401) $ 311,699 $ 486,819 $ (188,311) $ 298,508 (a) Includes property operating expense, real estate taxes and third party management expense. Unconsolidated real estate ventures: Investment in real estate ventures, at equity Equity in income (loss) of real estate venture As of Year ended December 31, December 31, 2023 December 31, 2022 2023 2022 2021 Philadelphia CBD $ 450,136 $ 387,301 $ (25,793) $ (11,764) $ (15,191) Mid-Atlantic Office JV — 31,005 (26,448) 412 932 MAP Venture (48,733) (35,411) (10,581) (8,340) (8,683) Austin, Texas 79,160 65,426 — — — Other $ 71,931 $ 83,903 $ (15,093) $ (2,324) $ (3,755) Total $ 552,494 $ 532,224 $ (77,915) $ (22,016) $ (26,697)
Schedule of Reconciliation of Consolidated Net Income to Consolidated NOI	The following is a reconciliation of consolidated net income (loss), as defined by GAAP, to consolidated NOI, (in thousands): Year Ended December 31, 2023 2022 2021 Net income (loss) $ (197,403) $ 53,992 $ 12,366 Plus: Interest expense 95,456 68,764 62,617 Interest expense - amortization of deferred financing costs 4,369 3,091 2,836 Depreciation and amortization 188,797 177,984 178,105 General and administrative expenses 34,862 35,006 30,153 Equity in loss of unconsolidated real estate ventures 77,915 22,016 26,697 Provision for impairment 131,573 4,663 — Gain (loss) on early extinguishment of debt (138) 435 — Less: Interest and investment income 1,671 1,905 8,295 Income tax provision (72) (55) (47) Net gain on disposition of real estate 7,736 17,677 142 Net gain on sale of undepreciated real estate 1,211 8,007 2,903 Net gain on real estate venture transactions 181 26,718 2,973 Consolidated net operating income $ 324,704 $ 311,699 $ 298,508

ORGANIZATION OF THE PARENT CO_3

ORGANIZATION OF THE PARENT COMPANY AND THE OPERATING PARTNERSHIP - Narrative (Details)	12 Months Ended
	Dec. 31, 2023 a ft² parcel property managementCompany
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of real estate properties | property	72
Rentable square feet	13,011,094
Number of management companies | managementCompany	7
Leashold Interest Land
Organization of The Parent Company and The Operating Partnership [Line Items]
Lease agreement term (in years)	99 years
Unconsolidated Properties | Unconsolidated Real Estate Ventures
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of real estate properties | property	12
Parent Company
Organization of The Parent Company and The Operating Partnership [Line Items]
Rentable square feet	12,100,000
Areas of land held for development (in acres) | a	141.6
Lease agreement term (in years)	99 years
Area of additional undeveloped parcels of land with option to purchase | a	5.1
Parent Company | Parcel of land
Organization of The Parent Company and The Operating Partnership [Line Items]
Lease agreement term (in years)	99 years
Parent Company | Leashold Interest Land
Organization of The Parent Company and The Operating Partnership [Line Items]
Areas of land held for development (in acres) | a	0.8
Number of parcels of land | parcel	1
Wholly-owned Management Company Subsidiaries
Organization of The Parent Company and The Operating Partnership [Line Items]
Rentable square feet	22,400,000
Wholly-owned Management Company Subsidiaries | Wholly Owned Properties
Organization of The Parent Company and The Operating Partnership [Line Items]
Rentable square feet	13,000,000
Wholly-owned Management Company Subsidiaries | Partially Owned Properties
Organization of The Parent Company and The Operating Partnership [Line Items]
Rentable square feet	9,400,000
Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	99.70%
BRSCO | BRANDYWINE OPERATING PARTNERSHIP, L.P. | Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	100%
BMI | BRANDYWINE OPERATING PARTNERSHIP, L.P. | Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	100%
BPI | BRANDYWINE OPERATING PARTNERSHIP, L.P. | Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	100%
BBL | BRANDYWINE OPERATING PARTNERSHIP, L.P. | Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	100%
BPM | BRANDYWINE OPERATING PARTNERSHIP, L.P. | Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	100%
BBS | BRANDYWINE OPERATING PARTNERSHIP, L.P. | Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	100%
BGCS | BRANDYWINE OPERATING PARTNERSHIP, L.P. | Brandywine Operating Partnership LP
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the operating partnership	100%

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)	Dec. 31, 2023 ft² property
Real Estate Properties [Line Items]
Number of Properties | property	72
Rentable Square Feet | ft²	13,011,094
Core Properties
Real Estate Properties [Line Items]
Number of Properties | property	69
Rentable Square Feet | ft²	12,698,115
Office properties
Real Estate Properties [Line Items]
Number of Properties | property	65
Rentable Square Feet | ft²	11,773,665
Mixed-use properties
Real Estate Properties [Line Items]
Number of Properties | property	4
Rentable Square Feet | ft²	924,450
Development property
Real Estate Properties [Line Items]
Number of Properties | property	2
Rentable Square Feet | ft²	144,685
Recently completed - not stabilized property
Real Estate Properties [Line Items]
Number of Properties | property	1
Rentable Square Feet | ft²	168,294

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Principles of Consolidation (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Assets	$ 3,732,447	$ 3,874,505
Liabilities	2,408,290	2,241,171
Variable Interest Entity
Variable Interest Entity [Line Items]
Assets	34,400	47,300
Liabilities	$ 21,500	$ 21,000

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Purchase Price Allocation and Depreciation and Amortization (Details)	12 Months Ended
	Dec. 31, 2023
Minimum
Construction in Progress [Line Items]
Expected lease-up periods	4 months
Minimum | Buildings and Improvements
Construction in Progress [Line Items]
Buildings and improvements useful life	5 years
Minimum | Tenant Improvements
Construction in Progress [Line Items]
Buildings and improvements useful life	1 year
Maximum
Construction in Progress [Line Items]
Expected lease-up periods	12 months
Maximum | Buildings and Improvements
Construction in Progress [Line Items]
Buildings and improvements useful life	55 years
Maximum | Tenant Improvements
Construction in Progress [Line Items]
Buildings and improvements useful life	16 years

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Impairment of Real Estate Assets (Details)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Disposition of assets, holding period	10 years

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Deferred Costs (Details)	Dec. 31, 2023
Minimum
Lessor, Lease, Description [Line Items]
Deferred cost, amortization period	1 year
Maximum
Lessor, Lease, Description [Line Items]
Deferred cost, amortization period	16 years

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Total revenue	$ 514,651	$ 506,100	$ 486,819
Corporate
Disaggregation of Revenue [Line Items]
Total revenue	19,607	23,346	18,835
Rents
Disaggregation of Revenue [Line Items]
Total revenue	479,849	470,851	451,519
Rents | Corporate
Disaggregation of Revenue [Line Items]
Total revenue	(1,441)	(1,930)	(2,497)
Total lease revenue
Disaggregation of Revenue [Line Items]
Total revenue	469,047	453,198	433,766
Total lease revenue | Corporate
Disaggregation of Revenue [Line Items]
Total revenue	(1,441)	(1,930)	(2,497)
Fixed rent
Disaggregation of Revenue [Line Items]
Total revenue	372,069	353,387	343,924
Fixed rent | Corporate
Disaggregation of Revenue [Line Items]
Total revenue	(1,895)	(1,895)	(2,240)
Variable rent
Disaggregation of Revenue [Line Items]
Total revenue	96,978	99,811	89,842
Variable rent | Corporate
Disaggregation of Revenue [Line Items]
Total revenue	454	(35)	(257)
Amortization of deferred market rents
Disaggregation of Revenue [Line Items]
Total revenue	1,291	2,582	5,377
Amortization of deferred market rents | Corporate
Disaggregation of Revenue [Line Items]
Total revenue	0	0	0
Daily parking & hotel flexible stay
Disaggregation of Revenue [Line Items]
Total revenue	9,511	15,071	12,376
Daily parking & hotel flexible stay | Corporate
Disaggregation of Revenue [Line Items]
Total revenue	0	0	0
Third party management fees, labor reimbursement and leasing
Disaggregation of Revenue [Line Items]
Total revenue	24,417	24,132	26,444
Third party management fees, labor reimbursement and leasing | Corporate
Disaggregation of Revenue [Line Items]
Total revenue	18,486	17,613	15,440
Other income
Disaggregation of Revenue [Line Items]
Total revenue	10,385	11,117	8,856
Other income | Corporate
Disaggregation of Revenue [Line Items]
Total revenue	2,562	7,663	5,892
Philadelphia CBD
Disaggregation of Revenue [Line Items]
Total revenue		220,875
Philadelphia CBD | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	230,933	220,876	207,858
Philadelphia CBD | Rents
Disaggregation of Revenue [Line Items]
Total revenue		218,078
Philadelphia CBD | Rents | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	223,537		204,848
Philadelphia CBD | Total lease revenue
Disaggregation of Revenue [Line Items]
Total revenue		202,380
Philadelphia CBD | Total lease revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	214,410		191,026
Philadelphia CBD | Fixed rent
Disaggregation of Revenue [Line Items]
Total revenue		151,034
Philadelphia CBD | Fixed rent | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	159,732		149,441
Philadelphia CBD | Variable rent
Disaggregation of Revenue [Line Items]
Total revenue		51,346
Philadelphia CBD | Variable rent | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	54,678		41,585
Philadelphia CBD | Amortization of deferred market rents
Disaggregation of Revenue [Line Items]
Total revenue		1,308
Philadelphia CBD | Amortization of deferred market rents | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	649		2,064
Philadelphia CBD | Daily parking & hotel flexible stay
Disaggregation of Revenue [Line Items]
Total revenue		14,390
Philadelphia CBD | Daily parking & hotel flexible stay | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	8,478		11,758
Philadelphia CBD | Third party management fees, labor reimbursement and leasing
Disaggregation of Revenue [Line Items]
Total revenue		287
Philadelphia CBD | Third party management fees, labor reimbursement and leasing | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	405		893
Philadelphia CBD | Other income
Disaggregation of Revenue [Line Items]
Total revenue		2,510
Philadelphia CBD | Other income | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	6,991		2,117
Pennsylvania Suburbs
Disaggregation of Revenue [Line Items]
Total revenue		128,940
Pennsylvania Suburbs | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	129,300	128,940	124,566
Pennsylvania Suburbs | Rents
Disaggregation of Revenue [Line Items]
Total revenue		128,551
Pennsylvania Suburbs | Rents | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	128,923		124,256
Pennsylvania Suburbs | Total lease revenue
Disaggregation of Revenue [Line Items]
Total revenue		128,541
Pennsylvania Suburbs | Total lease revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	128,923		124,106
Pennsylvania Suburbs | Fixed rent
Disaggregation of Revenue [Line Items]
Total revenue		116,926
Pennsylvania Suburbs | Fixed rent | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	118,856		113,748
Pennsylvania Suburbs | Variable rent
Disaggregation of Revenue [Line Items]
Total revenue		11,615
Pennsylvania Suburbs | Variable rent | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	10,067		10,358
Pennsylvania Suburbs | Amortization of deferred market rents
Disaggregation of Revenue [Line Items]
Total revenue		10
Pennsylvania Suburbs | Amortization of deferred market rents | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	0		(9)
Pennsylvania Suburbs | Daily parking & hotel flexible stay
Disaggregation of Revenue [Line Items]
Total revenue		0
Pennsylvania Suburbs | Daily parking & hotel flexible stay | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	0		159
Pennsylvania Suburbs | Third party management fees, labor reimbursement and leasing
Disaggregation of Revenue [Line Items]
Total revenue		35
Pennsylvania Suburbs | Third party management fees, labor reimbursement and leasing | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	38		34
Pennsylvania Suburbs | Other income
Disaggregation of Revenue [Line Items]
Total revenue		354
Pennsylvania Suburbs | Other income | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	339		276
Austin, Texas
Disaggregation of Revenue [Line Items]
Total revenue		96,329
Austin, Texas | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	95,505	96,328	101,680
Austin, Texas | Rents
Disaggregation of Revenue [Line Items]
Total revenue		95,414
Austin, Texas | Rents | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	94,657		100,826
Austin, Texas | Total lease revenue
Disaggregation of Revenue [Line Items]
Total revenue		93,789
Austin, Texas | Total lease revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	93,307		97,395
Austin, Texas | Fixed rent
Disaggregation of Revenue [Line Items]
Total revenue		60,831
Austin, Texas | Fixed rent | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	63,209		62,545
Austin, Texas | Variable rent
Disaggregation of Revenue [Line Items]
Total revenue		32,958
Austin, Texas | Variable rent | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	30,098		34,850
Austin, Texas | Amortization of deferred market rents
Disaggregation of Revenue [Line Items]
Total revenue		1,264
Austin, Texas | Amortization of deferred market rents | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	642		3,322
Austin, Texas | Daily parking & hotel flexible stay
Disaggregation of Revenue [Line Items]
Total revenue		361
Austin, Texas | Daily parking & hotel flexible stay | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	708		109
Austin, Texas | Third party management fees, labor reimbursement and leasing
Disaggregation of Revenue [Line Items]
Total revenue		486
Austin, Texas | Third party management fees, labor reimbursement and leasing | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	516		452
Austin, Texas | Other income
Disaggregation of Revenue [Line Items]
Total revenue		429
Austin, Texas | Other income | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	332		402
Other
Disaggregation of Revenue [Line Items]
Total revenue		36,610
Other | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	39,306		33,880
Other | Rents
Disaggregation of Revenue [Line Items]
Total revenue		30,738
Other | Rents | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	34,173		24,086
Other | Total lease revenue
Disaggregation of Revenue [Line Items]
Total revenue		30,418
Other | Total lease revenue | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	33,848		23,736
Other | Fixed rent
Disaggregation of Revenue [Line Items]
Total revenue		26,491
Other | Fixed rent | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	32,167		20,430
Other | Variable rent
Disaggregation of Revenue [Line Items]
Total revenue		3,927
Other | Variable rent | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	1,681		3,306
Other | Amortization of deferred market rents
Disaggregation of Revenue [Line Items]
Total revenue		0
Other | Amortization of deferred market rents | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	0		0
Other | Daily parking & hotel flexible stay
Disaggregation of Revenue [Line Items]
Total revenue		320
Other | Daily parking & hotel flexible stay | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	325		350
Other | Third party management fees, labor reimbursement and leasing
Disaggregation of Revenue [Line Items]
Total revenue		5,711
Other | Third party management fees, labor reimbursement and leasing | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	4,972		9,625
Other | Other income
Disaggregation of Revenue [Line Items]
Total revenue		$ 161
Other | Other income | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	$ 161		$ 169

SUMMARY OF SIGNIFICANT ACCOUN_9

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Income Taxes (Details) - USD ($) $ in Billions	Dec. 31, 2023	Dec. 31, 2022
Income Tax Contingency [Line Items]
Tax basis of assets, cost for income tax purposes	$ 3	$ 3.2
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Income Tax Contingency [Line Items]
Tax basis of assets, cost for income tax purposes	$ 3	$ 3.2

REAL ESTATE INVESTMENTS - Sched

REAL ESTATE INVESTMENTS - Schedule of Gross Carrying Value of Operating Properties (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Real Estate [Abstract]
Land	$ 394,669	$ 403,998
Building and improvements	2,671,024	2,760,357
Tenant improvements	476,539	452,885
Total	$ 3,542,232	$ 3,617,240

REAL ESTATE INVESTMENTS - Narra

REAL ESTATE INVESTMENTS - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Real Estate [Abstract]
Internal direct construction costs capitalized related to development of properties and land holdings	$ 8,857	$ 9,332	$ 7,902
Capitalized interest	$ 5,200	$ 4,700	$ 7,000

REAL ESTATE INVESTMENTS - Sch_2

REAL ESTATE INVESTMENTS - Schedule of Capitalized Construction Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Internal direct construction costs	$ 8,857	$ 9,332	$ 7,902
Capitalized interest	5,200	4,700	7,000
Development
Property, Plant and Equipment [Line Items]
Internal direct construction costs	4,096	5,343	4,815
Redevelopment
Property, Plant and Equipment [Line Items]
Internal direct construction costs	944	1,484	1,170
Tenant Improvements
Property, Plant and Equipment [Line Items]
Internal direct construction costs	$ 3,817	$ 2,505	$ 1,917

REAL ESTATE INVESTMENTS - Sch_3

REAL ESTATE INVESTMENTS - Schedule of Acquired Properties (Details) $ in Thousands				12 Months Ended
	Oct. 27, 2023 USD ($) a	Apr. 29, 2022 USD ($)	Jan. 21, 2022 USD ($) a	Dec. 31, 2023 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Apr. 29, 2022 ft²	Apr. 29, 2022 a
Business Acquisition [Line Items]
Purchase Price				$ 7,747	$ 3,446	$ 0
Area of real estate property | ft²				13,011,094
Land | 165 King of Prussia Road
Business Acquisition [Line Items]
Land area | a	1.1
Purchase Price	$ 8,550
Land | 631 Park Avenue
Business Acquisition [Line Items]
Land area | a			3.3
Purchase Price			$ 3,650
Land | 3151 Market Street
Business Acquisition [Line Items]
Land area							0.8	0.8
Purchase Price		$ 27,349
Lease agreement term (in years)		99 years
Prepaid rent		$ 19,500
Area of real estate property | ft²							500,000
Land | Schuylkill Yards Project
Business Acquisition [Line Items]
Area of real estate property | ft²							200,000
Operating lease costs, capitalized		$ 7,800

REAL ESTATE INVESTMENTS - Sch_4

REAL ESTATE INVESTMENTS - Schedule of Office Properties Sold (Details) $ in Thousands

12 Months Ended

Dec. 27, 2023 USD ($) a

Dec. 07, 2023 USD ($) a

Dec. 01, 2023 USD ($) ft²

Oct. 31, 2023 USD ($) ft²

Aug. 04, 2023 USD ($) ft²

Nov. 22, 2022 USD ($) ft²

Sep. 30, 2022 USD ($)

Jul. 29, 2022 USD ($) a

Jul. 14, 2022 USD ($) a ft²

Jun. 28, 2022 USD ($)

Apr. 14, 2022 USD ($) a

Jan. 20, 2022 USD ($) a

Sep. 08, 2021 USD ($) ft²

Jul. 06, 2021 USD ($) ft²

Feb. 02, 2021 USD ($) a

Dec. 31, 2023 USD ($) ft²

Dec. 31, 2022 USD ($)

Dec. 31, 2021 USD ($)

Jan. 30, 2023 ft²

Jun. 28, 2022 ft²

Jun. 28, 2022 a

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Gain/(Loss) on Sale

$ 7,736

$ 17,677

$ 142

Area of real estate property | ft²

13,011,094

Recognized a provision for impairment

$ 16,700

Land | Dabney East

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | a

11.6

Sales Price

$ 1,600

Gain/(Loss) on Sale

$ 430

Land | Byberry

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | a

50

Sales Price

$ 9,641

Gain/(Loss) on Sale

$ 3,960

Land | 11501 Burnett Road

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | a

4.7

Sales Price

$ 32,513

Gain/(Loss) on Sale

$ 8,340

Land | 25 M Street

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | a

0.8

Sales Price

$ 29,675

Gain/(Loss) on Sale

$ 400

$ 3,836

Land | Gateway G & H

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | a

10

Sales Price

$ 1,600

Gain/(Loss) on Sale

$ 897

Land | 1100 Lenox Drive

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | ft²

5

Sales Price

$ 2,575

Gain/(Loss) on Sale

$ 68

Land | 2100-2200 Lenox Drive

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | ft²

35.2

Sales Price

$ 8,900

Gain/(Loss) on Sale

$ 842

Land | Gibbsboro Portfolio

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Gain/(Loss) on Sale

700

Land | 3151 Market Street

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Area of real estate property | ft²

500,000

Land | 11501 Burnet Road

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | a

4.7

Sales Price

$ 32,500

Gain/(Loss) on Sale

$ 8,300

Office Properties | 8521 Leesburg Pike

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Rentable Square Feet/Acres | ft²

150,897

Sales Price

$ 11,000

Gain/(Loss) on Sale

$ 0

Office Properties | Three Barton Skyway

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Rentable Square Feet/Acres | ft²

173,302

Sales Price

$ 53,250

Gain/(Loss) on Sale

$ 0

Office Properties | 200 Barr Harbor Drive

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Rentable Square Feet/Acres | ft²

86,000

Sales Price

$ 30,500

Gain/(Loss) on Sale

$ 8,740

Office Properties | Gibbsboro Portfolio

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Gain/(Loss) on Sale

$ 100

Retail | 200 N. Radnor Chester Road

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Rentable Square Feet/Acres | ft²

17,884

Sales Price

$ 14,200

Gain/(Loss) on Sale

$ 7,735

Leasehold Interest | 3151 Market Street

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | a

0.8

Sales Price

$ 30,394

Gain/(Loss) on Sale

2,583

Leasehold Interest | 3025 JFK Boulevard

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area | a

1

Sales Price

$ 34,800

Gain/(Loss) on Sale

$ 2,000

Leasehold Interest | 3151 Market Street

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Rentable Square Feet/Acres | ft²

200,000

Sales Price

30,400

Gain/(Loss) on Sale

$ 2,600

Lease agreement term (in years)

99 years

Office/Land | Gibbsboro Portfolio

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Land area

42,809

4

Sales Price

$ 4,100

Gain/(Loss) on Sale

$ 831

REAL ESTATE INVESTMENTS - 3025

REAL ESTATE INVESTMENTS - 3025 JFK Venture (Narrative) (Details) $ in Thousands		12 Months Ended
	Feb. 02, 2021 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Feb. 02, 2021 a	Feb. 02, 2021 ft²
Schedule of Investments [Line Items]
Investment in real estate ventures, at equity		$ 552,494	$ 532,224
Net gain on sale of undepreciated real estate		$ 1,211	$ 8,007	$ 2,903
3025 JFK Boulevard
Schedule of Investments [Line Items]
Lease agreement term (in years)	99 years
Land area					1	1
Investment in real estate ventures, at equity	$ 34,800
Net gain on sale of undepreciated real estate	$ 2,000

REAL ESTATE INVESTMENTS - 3151

REAL ESTATE INVESTMENTS - 3151 Market Venture (Narrative) (Details) $ in Thousands		3 Months Ended	12 Months Ended
	Jul. 14, 2022 USD ($) ft²	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 30, 2023 ft²
Schedule of Investments [Line Items]
Area of real estate property | ft²			13,011,094
Net gain on disposition of real estate			$ 7,736	$ 17,677	$ 142
Land | 3151 Market Street
Schedule of Investments [Line Items]
Area of real estate property | ft²	500,000
Leasehold Interest | 3151 Market Street
Schedule of Investments [Line Items]
Lease agreement term (in years)	99 years
Sales price	$ 30,400
Net gain on disposition of real estate	$ 2,600
Operating lease costs, capitalized		$ 7,800
Rentable area (in square feet) | ft²						200,000
Net gain from remeasurement of investment in real estate ventures		$ 800

REAL ESTATE INVESTMENTS - Held

REAL ESTATE INVESTMENTS - Held for Use Impairment and Sale (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) property	Dec. 31, 2022 USD ($)	Jan. 20, 2022 USD ($)	Dec. 31, 2021 USD ($) a parcel
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of properties held for use		$ 4.7
Number of real estate properties | property	72
Impairment long lived asset held for use statement of income or comprehensive income extensible enumeration not disclosed flag	impairment losses
Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of properties held for use	$ 103.2
Number of real estate properties | property	3
Other | Discount Rates | Valuation Technique, Discounted Cash Flow
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt securities, trading, measurement input	0.1000
Other | Measurement Input, Capitalization Rate | Valuation Technique, Discounted Cash Flow
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt securities, trading, measurement input	0.0850
Pennsylvania Suburbs | Office Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Provision for impairment on assets held for sale	$ 11.7
Held for Sale Properties Included in Continuing Operations | Other Land
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, net				$ 0.6
Aggregate sales price			$ 1.6
Held for Sale Properties Included in Continuing Operations | Other Land | Other
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of land parcels | parcel				2
Land area | a				10

INVESTMENT IN UNCONSOLIDATED _3

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Narrative (Details) $ in Thousands, ft² in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) ft² a property apartment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property	72
Investment balance | $	$ 552,494	$ 532,224
Accounts receivable | $	11,977	11,003
Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Accounts receivable | $	3,500	2,900
Management Fees | Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Service and other revenue | $	8,100	8,200	$ 8,100
Lease Commission Income | Real Estate Venture
Schedule of Equity Method Investments [Line Items]
Service and other revenue | $	3,800	$ 2,500	$ 3,800
Unconsolidated Real Estate Ventures
Schedule of Equity Method Investments [Line Items]
Investment balance | $	$ 552,500
Unconsolidated Real Estate Ventures | Minimum
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	15%
Unconsolidated Real Estate Ventures | Maximum
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	78%
Unconsolidated Real Estate Ventures | Office Properties
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in real estate ventures | property	5
Rentable area (in square feet) | ft²	9.1
Unconsolidated Real Estate Ventures | Other Liabilities
Schedule of Equity Method Investments [Line Items]
Investment balance | $	$ 48,700
Unconsolidated Real Estate Ventures | Unconsolidated Properties
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property	12
Number of real estate properties with negative investment balances | property	1
Unconsolidated Real Estate Ventures | Land Held For Development
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in real estate ventures | property	2
Land area | a	1.4
Unconsolidated Real Estate Ventures | Land Under Active Development
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in real estate ventures | property	4
Land area | a	7.5
Unconsolidated Real Estate Ventures | Mixed Use Tower
Schedule of Equity Method Investments [Line Items]
Number of unconsolidated investments in real estate ventures | property	1
Rentable area (in square feet) | ft²	0.2
Number of property units | apartment	250

INVESTMENT IN UNCONSOLIDATED _4

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Schedule of Investment in Real Estate Ventures and Share of Real Estate Ventures' Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 02, 2023	Nov. 30, 2022	Feb. 02, 2021	Dec. 21, 2020
Schedule of Equity Method Investments [Line Items]
Carrying Amount	$ 552,494	$ 532,224
Company's unconsolidated real estate venture Income (Loss)	(77,915)	(22,016)	$ (26,697)
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 1,412,758	1,204,779
Commerce Square Venture
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	78%			8%
Carrying Amount	$ 272,216	238,105
Company's unconsolidated real estate venture Income (Loss)	(18,791)	(12,128)	(15,501)
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 220,000	206,737
Mid-Atlantic Office JV
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	40%						40%
Carrying Amount	$ 0	31,005
Company's unconsolidated real estate venture Income (Loss)	(26,448)	412	932
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 132,770	128,904
Herndon Innovation Center Metro Portfolio Venture, LLC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	15%
Carrying Amount	$ 3,518	15,304
Company's unconsolidated real estate venture Income (Loss)	(11,854)	(536)	(174)
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 233,443	207,302
MAP Venture
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50%
Carrying Amount	$ (48,733)	(35,411)
Company's unconsolidated real estate venture Income (Loss)	(10,580)	(8,340)	(8,683)
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 179,842	182,053
Cira Square
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	20%
Carrying Amount	$ 25,242	27,815
Company's unconsolidated real estate venture Income (Loss)	(2,474)	(985)	0
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 257,700	257,700
4040 Wilson Venture
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50%
Carrying Amount	$ 29,419	29,633
Company's unconsolidated real estate venture Income (Loss)	(2,536)	(1,211)	(2,258)
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 145,000	145,070
1919 Venture
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50%				50%
Carrying Amount	$ 0	0
Company's unconsolidated real estate venture Income (Loss)	0	1,392	427
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 0	0
Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50%
Carrying Amount	$ 0	0
Company's unconsolidated real estate venture Income (Loss)	0	0	(721)
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 0	0
3025 JFK Boulevard
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	58%					55%
Carrying Amount	$ 62,034	57,630
Company's unconsolidated real estate venture Income (Loss)	(4,456)	(35)	(118)
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 152,032	60,118
JBG 51 N Street
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	70%
Carrying Amount	$ 21,150	21,208
Company's unconsolidated real estate venture Income (Loss)	(435)	(382)	(402)
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 0	0
JBG 1250 First Street Office
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	70%
Carrying Amount	$ 17,843	17,759
Company's unconsolidated real estate venture Income (Loss)	(269)	(195)	(199)
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 0	0
3151 Market Street Venture
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	64%
Carrying Amount	$ 90,645	63,751
Company's unconsolidated real estate venture Income (Loss)	(72)	(8)	0
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 0	0
One Uptown - Office
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	57%
Carrying Amount	$ 47,036	34,980
Company's unconsolidated real estate venture Income (Loss)	0	0	0
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 51,701	16,895
One Uptown - Multifamily
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50%
Carrying Amount	$ 32,124	30,445
Company's unconsolidated real estate venture Income (Loss)	0	0	$ 0
Unconsolidated Real Estate Venture Debt at 100%, gross	$ 40,270	$ 0

INVESTMENT IN UNCONSOLIDATED _5

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Financial Position of Real Estate Ventures (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Net property	$ 2,675,272	$ 2,904,788
Other assets	86,051	78,667
Other liabilities	63,729	52,331
Debt, net	2,138,832
Equity	1,324,157	1,633,334	$ 1,701,219	$ 1,804,648
Investment In Nonconsolidated Real Estate
Schedule of Equity Method Investments [Line Items]
Net property	2,339,921	2,117,226
Other assets	534,658	506,213
Other liabilities	443,536	446,101
Debt, net	1,407,858	1,198,213
Equity	$ 1,023,185	$ 979,125

INVESTMENT IN UNCONSOLIDATED _6

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Schedule of Results of Operations of Real Estate Ventures with Interests (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Revenue	$ 514,651	$ 506,100	$ 486,819
Operating expenses	(545,179)	(412,054)	(396,569)
Interest expense, net	(95,456)	(68,764)	(62,617)
Depreciation and amortization	(188,797)	(177,984)	(178,105)
Provision for impairment	(131,573)	(4,663)	0
Net income (loss)	(197,403)	53,992	12,366
Other-than-temporary impairment	(37,176)	0	0
Equity in loss of unconsolidated real estate ventures	(77,915)	(22,016)	(26,697)
Investment In Nonconsolidated Real Estate
Schedule of Equity Method Investments [Line Items]
Revenue	232,895	244,981	214,792
Operating expenses	(122,181)	(124,608)	(117,273)
Interest expense, net	(78,909)	(49,007)	(30,569)
Depreciation and amortization	(100,205)	(103,378)	(97,147)
Provision for impairment	0	0	(1,393)
Net income (loss)	(68,400)	(32,012)	(31,590)
Company's share of net loss	(39,637)	(21,594)	(25,972)
Basis adjustments and other	$ (1,102)	$ (422)	$ (725)

INVESTMENT IN UNCONSOLIDATED _7

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Schedule of Maturities of Long-term Debt (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Schedule of Equity Method Investments [Line Items]
2024	$ 340,000
2025	70,000
2026	13,824
2027	700,000
2028	595,000
Thereafter	428,610
Total principal payments	2,147,434
Net deferred financing costs	(10,480)
Outstanding indebtedness	2,138,832
Unconsolidated Real Estate Ventures
Schedule of Equity Method Investments [Line Items]
2024	803,756
2025	152,032
2026	236,971
2027	0
2028	220,000
Thereafter	0
Total principal payments	1,412,759
Net deferred financing costs	(4,901)
Outstanding indebtedness	$ 1,407,858

INVESTMENT IN UNCONSOLIDATED _8

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - One Uptown Ventures (Details) $ in Thousands		12 Months Ended
	Jul. 29, 2022 USD ($) numberOfLoan	Dec. 31, 2023 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 01, 2021 USD ($) ft² property apartment
Schedule of Equity Method Investments [Line Items]
Investment in real estate ventures, at equity		$ 552,494	$ 532,224
Area of real estate property | ft²		13,011,094
Principal balance outstanding		$ 2,147,434
Payments to acquire investment		85,922	47,428	$ 31,643
Investments in equity securities		552,494	532,224
Unsecured Debt
Schedule of Equity Method Investments [Line Items]
Principal balance outstanding		1,888,610	1,971,411
Unsecured Debt | $600 million Unsecured Credit Facility
Schedule of Equity Method Investments [Line Items]
Principal balance outstanding		$ 0	88,500
Unsecured Debt | Daily SOFR Adjustment | $600 million Unsecured Credit Facility
Schedule of Equity Method Investments [Line Items]
Basis spread on interest rate (as percent)		0.10%
One Uptown Venture
Schedule of Equity Method Investments [Line Items]
Investment in real estate ventures, at equity					$ 335,600
Number of apartment residences | apartment					341
Joint venture, funding committed by other party					$ 64,500
Equity method investment, ownership percentage		50%
Investments in equity securities		$ 32,124	$ 30,445
One Uptown Venture | Carry Guarantee | Loans Payable
Schedule of Equity Method Investments [Line Items]
Guarantee obligations, payment (as percent)	30%
One Uptown Venture | Limited Payment Guarantee | Loans Payable
Schedule of Equity Method Investments [Line Items]
Guarantee obligations, payment (as percent)	15%
One Uptown Venture | Construction Loans
Schedule of Equity Method Investments [Line Items]
Number of loans closed | numberOfLoan	2
Principal balance outstanding	$ 121,700
One Uptown Venture | Construction Loans | Multifamily Joint Venture
Schedule of Equity Method Investments [Line Items]
Principal balance outstanding	$ 85,000
One Uptown Venture | Construction Loans | Secured Overnight Financing Rate (SOFR)
Schedule of Equity Method Investments [Line Items]
Basis spread on interest rate (as percent)	3%
One Uptown Venture | Construction Loans | Secured Overnight Financing Rate (SOFR) | Multifamily Joint Venture
Schedule of Equity Method Investments [Line Items]
Basis spread on interest rate (as percent)	2.45%
One Uptown Venture | Preferred Stock
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage					50%
One Uptown Venture | Common Stock
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage					50%
One Uptown Venture | Canyon Partners Real Estate
Schedule of Equity Method Investments [Line Items]
Number of joint ventures | property					2
One Uptown Venture | Class A Workspace
Schedule of Equity Method Investments [Line Items]
Area of real estate property | ft²					348,000
One Uptown Venture | Street Level Retail
Schedule of Equity Method Investments [Line Items]
Area of real estate property | ft²					15,000
One Uptown Office
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			50%
Payments to acquire investment		$ 10,800
One Uptown - Office
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		57%
Investments in equity securities		$ 47,036	$ 34,980

INVESTMENT IN UNCONSOLIDATED _9

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - 3151 Market Street Venture (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jul. 14, 2022 USD ($) ft²
Schedule of Equity Method Investments [Line Items]
Area of real estate property | ft²	13,011,094
Investment in real estate ventures, at equity	$ 552,494	$ 532,224
Payments to acquire investment	85,922	47,428	$ 31,643
Investments in equity securities	$ 552,494	$ 532,224
3151 Market Street
Schedule of Equity Method Investments [Line Items]
Area of real estate property | ft²				417,000
Investment in real estate ventures, at equity				$ 317,000
3151 Market Street | Joint Venture With Unaffiliated Third Party
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	64%	58%
Payments to acquire investment	$ 15,400
Investments in equity securities	$ 90,600
3151 Market Street | Joint Venture With Unaffiliated Third Party
Schedule of Equity Method Investments [Line Items]
Investment in real estate ventures, at equity				$ 49,900
3151 Market Street | Joint Venture With Unaffiliated Third Party | Joint Venture With Unaffiliated Third Party
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage				35%

INVESTMENT IN UNCONSOLIDATED_10

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Cira Square (Details)		12 Months Ended
	Mar. 17, 2022 USD ($) ft²	Dec. 31, 2023 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 02, 2023 USD ($)
Schedule of Equity Method Investments [Line Items]
Area of real estate property | ft²		13,011,094
Purchase price		$ 7,747,000	$ 3,446,000	$ 0
Secured fix rate debt
Schedule of Equity Method Investments [Line Items]
Debt instrument, face amount					$ 220,000,000
Cira Square REIT, LLC
Schedule of Equity Method Investments [Line Items]
Cost	$ 383,000,000
Equity method investment, ownership percentage	20%
Purchase price	$ 28,600,000
Interest rate, maximum	6.75%
Cira Square REIT, LLC | Secured Overnight Financing Rate (SOFR)
Schedule of Equity Method Investments [Line Items]
Basis spread on interest rate (as percent)	3.50%
Cira Square REIT, LLC | Secured fix rate debt
Schedule of Equity Method Investments [Line Items]
Debt instrument, face amount	$ 257,700,000
Office Properties | Cira Square REIT, LLC
Schedule of Equity Method Investments [Line Items]
Area of real estate property | ft²	862,692

INVESTMENT IN UNCONSOLIDATED_11

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - 4040 Wilson Venture (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) ft² a property	Jan. 03, 2023	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property	72
Area of real estate property | ft²	13,011,094
Principal balance outstanding	$ 2,147,434
Secured fix rate debt
Schedule of Equity Method Investments [Line Items]
Principal balance outstanding	$ 255,671		$ 0
4040 Wilson Venture
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property	1
Area of real estate property | ft²	225,000
Land area | a	250
Equity method investment, ownership percentage	50%
4040 Wilson Venture | Secured Overnight Financing Rate (SOFR)
Schedule of Equity Method Investments [Line Items]
Debt instrument, interest rate		5.71%
4040 Wilson Venture | Construction Loans
Schedule of Equity Method Investments [Line Items]
Principal balance outstanding				$ 150,000
4040 Wilson Venture | Secured fix rate debt | Mortgage Loan Secured By Property
Schedule of Equity Method Investments [Line Items]
Principal balance outstanding				$ 155,000
4040 Wilson Venture | Secured fix rate debt | Mortgage Loan Secured By Property | Secured Overnight Financing Rate (SOFR)
Schedule of Equity Method Investments [Line Items]
Basis spread on interest rate (as percent)	1.80%

INVESTMENT IN UNCONSOLIDATED_12

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Brandywine - AI Venture (Details) $ in Thousands		12 Months Ended
	Nov. 09, 2021 USD ($) ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Net gain on real estate venture transactions		$ 181	$ 26,718	$ 2,973
Fairview Properties | Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Provision for impairment on assets held for sale				1,400
Fairview Properties | Brandywine - AI Venture LLC | Brandywine Realty Trust
Schedule of Equity Method Investments [Line Items]
Provision for impairment on assets held for sale				$ 700
Falls Church, Virginia | Brandywine - AI Venture LLC
Schedule of Equity Method Investments [Line Items]
Rentable area (in square feet) | ft²	183,618
Aggregate sales price	$ 27,600
Gross proceeds from sale	12,600
Net gain on real estate venture transactions	$ 3,000

INVESTMENT IN UNCONSOLIDATED_13

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - 3025 JFK Venture (Details) $ in Thousands		12 Months Ended
	Feb. 02, 2021 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jul. 23, 2021 USD ($)	Feb. 02, 2021 a	Feb. 02, 2021 ft²	Feb. 02, 2021
Schedule of Equity Method Investments [Line Items]
Investment in real estate ventures, at equity		$ 552,494	$ 532,224
Payments to acquire investment		85,922	47,428	$ 31,643
Derivative, notional amount		$ 250,000	250,000
3025 JFK Boulevard
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		58%						55%
3025 JFK Venture | Interest Rate Cap
Schedule of Equity Method Investments [Line Items]
Debt instrument, interest rate, stated percentage		3%
Derivative, notional amount		$ 148,000
Derivative asset		$ 187,000
Debt instrument, maximum interest rate		6.60%
3025 JFK Venture | SOFR | Interest Rate Cap
Schedule of Equity Method Investments [Line Items]
Debt instrument, interest rate, stated percentage		3.60%
3025 JFK Boulevard
Schedule of Equity Method Investments [Line Items]
Lease agreement term (in years)	99 years
Land area						1	1
Investment in real estate ventures, at equity	$ 34,800
Area of building to be constructed | ft²							570,000
Estimated project cost	287,300
Joint venture, funding committed by other party	$ 45,200
Ownership interest held by partner								45%
3025 JFK Venture
Schedule of Equity Method Investments [Line Items]
Investment in real estate ventures, at equity					$ 34,800
Construction loan amount					$ 186,700
Joint venture, funding committed			$ 20,500
3025 JFK Venture | LIBOR
Schedule of Equity Method Investments [Line Items]
Debt instrument, interest rate, stated percentage					3.50%
Interest rate, floor					0.25%
3025 JFK Venture | 3025 JFK Venture
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		58%	55%
Payments to acquire investment		$ 7,100

INVESTMENT IN UNCONSOLIDATED_14

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Mid-Atlantic Office JV (Details) $ in Thousands		12 Months Ended
	Dec. 21, 2020 USD ($) ft² property	Dec. 31, 2023 USD ($) property	Dec. 31, 2022 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property		72
Investment in real estate ventures, at equity		$ 552,494	$ 532,224
Mid-Atlantic Office JV Loan
Schedule of Equity Method Investments [Line Items]
Secured construction loan with total borrowing capacity		18,500
Philadelphia CBD
Schedule of Equity Method Investments [Line Items]
Investment in real estate ventures, at equity		$ 450,136	$ 387,301
Mid-Atlantic Office JV
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	40%	40%
Ownership percentage of total common equity	20%
Joint venture, funding from debt	$ 147,400
Proceeds from issuance of secured debt	$ 120,800
Mid-Atlantic Office JV | Mid-Atlantic Office JV Loan | Maximum
Schedule of Equity Method Investments [Line Items]
Debt instrument, interest rate, stated percentage		5.70%
Mid-Atlantic Office JV | Mid-Atlantic Office JV Loan | LIBOR
Schedule of Equity Method Investments [Line Items]
Basis spread on interest rate (as percent)		3.15%
Mid-Atlantic Office JV | Preferred Equity Securities
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	25%
Investment in real estate ventures, at equity	$ 20,000
Mid-Atlantic Office JV | Common Equity Securities
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	15%
Office Properties | Mid-Atlantic Office JV
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property	12
Rentable area (in square feet) | ft²	1,128,645
Aggregate sales price	$ 192,900
Office Properties | Mid-Atlantic Office JV | Philadelphia CBD
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property	9
Office Properties | Mid-Atlantic Office JV | Metropolitan D C
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property	3

INVESTMENT IN UNCONSOLIDATED_15

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Commerce Square Venture (Details) - USD ($)		12 Months Ended
	Jun. 02, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Payments to acquire investment		$ 85,922,000	$ 47,428,000	$ 31,643,000
Commerce Square Venture
Schedule of Equity Method Investments [Line Items]
Payments to acquire investment	$ 46,500,000
Equity method investment, ownership percentage	8%	78%
Secured fix rate debt
Schedule of Equity Method Investments [Line Items]
Debt instrument, face amount	$ 220,000,000
Secured fix rate debt | Commerce Square Venture
Schedule of Equity Method Investments [Line Items]
Debt instrument, interest rate, stated percentage	7.79%

INVESTMENT IN UNCONSOLIDATED_16

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Hernadon Innovation Center Metro Portfolio Venture, LLC (Details) $ in Thousands	Dec. 31, 2023 USD ($) ft² property
Schedule of Equity Method Investments [Line Items]
Area of real estate property | ft²	13,011,094
Debt, net | $	$ 2,138,832
Herndon Innovation Center Metro Portfolio Venture, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	15%
Herndon Innovation Center Metro Portfolio Venture, LLC | Metropolitan Washington, D.C. - Office
Schedule of Equity Method Investments [Line Items]
Number of properties contributed to joint venture | property	8
Area of real estate property | ft²	1,293,197
Herndon Innovation Center Metro Portfolio Venture, LLC | Secured fix rate debt
Schedule of Equity Method Investments [Line Items]
Debt, net | $	$ 233,400
Herndon Innovation Center Metro Portfolio Venture, LLC | Minimum | Metropolitan Washington, D.C. - Office
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	15%
Herndon Innovation Center Metro Portfolio Venture, LLC | Maximum | Metropolitan Washington, D.C. - Office
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	85%

INVESTMENT IN UNCONSOLIDATED_17

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - MAP Venture (Details) - MAP Venture $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) ft² property extension
Schedule of Equity Method Investments [Line Items]
Ground lease annual payments	$ 11.9
Ground lease annual rent expense increase percentage through November 2025	2.50%
Ground lease annual rent expense increase after November 2025	2.50%
Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Number of office properties owned | property	58
Rentable area (in square feet) | ft²	3,924,783
Real estate investment, net	$ (48.7)
Variable Interest Entity, Not Primary Beneficiary | Secured fix rate debt
Schedule of Equity Method Investments [Line Items]
Debt instrument, number of extensions | extension	3
Extension period	2 months
Capitalized financing costs	$ 179.8

INVESTMENT IN UNCONSOLIDATED_18

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - 1919 Ventures (Details) - USD ($) $ in Millions	Nov. 30, 2022	Dec. 31, 2023
1919 Venture | Affiliated Entity
Schedule of Equity Method Investments [Line Items]
Repayments of debt	$ 44.4
1919 Venture
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	50%	50%
Gross sales	$ 83.2
Gain on disposal	$ 26.7

INVESTMENT IN UNCONSOLIDATED_19

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - JGB Ventures (Details)	Dec. 31, 2023 a joint_venture property
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | property	72
JBG 51 N Street
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	70%
Area owned by real estate venture of undeveloped parcels of land	0.9
JBG 51 N Street | JBG Ventures
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	30%
JBG 1250 First Street Office
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	70%
Area owned by real estate venture of undeveloped parcels of land	0.5
JBG 1250 First Street Office | JBG Ventures
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	30%
JBG Ventures
Schedule of Equity Method Investments [Line Items]
Number of real estate properties | joint_venture	2

DEBT AND PREFERRED EQUITY INV_2

DEBT AND PREFERRED EQUITY INVESTMENTS (Details)		12 Months Ended
	Nov. 30, 2022 USD ($)	Dec. 31, 2023 property	Dec. 31, 2018 USD ($)	Sep. 03, 2021 USD ($)	Dec. 31, 2020 USD ($) property
Summary of Investment Holdings [Line Items]
Number of real estate properties | property		72
Austin Preferred Equity Investment | Notes Receivable
Summary of Investment Holdings [Line Items]
Note receivable					$ 50,000,000
Number of real estate properties | property					2
Notes receivable, interest rate (as percent)		9%
Extension option term (in years)		1 year
Note receivable repurchased amount				$ 50,000,000
1919 Venture
Summary of Investment Holdings [Line Items]
Note receivable			$ 44,400,000
Notes receivable, interest rate (as percent)			4%
Debt, net			$ 44,400,000
Repayment of note receivable	$ 44,400,000
Equity method investment, ownership percentage	50%	50%

LEASES - Schedule of Operating

LEASES - Schedule of Operating Lease Future Contractual Lease Payments (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2024	$ 348,890
2025	344,575
2026	329,584
2027	294,997
2028	262,816
Thereafter	$ 944,863

LEASES - Narrative (Details)

LEASES - Narrative (Details)	12 Months Ended
	Dec. 31, 2023 lease property
Lessee, Lease, Description [Line Items]
Number of ground leases considered operating lease | lease	6
Number of properties subject to ground leases | property	3
Minimum
Lessee, Lease, Description [Line Items]
Lease terms (in years)	6 years
Maximum
Lessee, Lease, Description [Line Items]
Lease terms (in years)	61 years

LEASES - Schedule of Lease Cost

LEASES - Schedule of Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Fixed lease cost	$ 2,100	$ 2,100
Variable lease cost	57	67
Total	$ 2,157	$ 2,167
Weighted-average remaining lease term (years)	54 years	54 years 7 months 6 days
Weighted-average discount rate	6.30%	6.30%

LEASES - Schedule of Operatin_2

LEASES - Schedule of Operating Lease Liability Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Minimum Rent
2024	$ 1,305
2025	1,321
2026	1,338
2027	1,355
2028	1,373
Thereafter	105,065
Total lease payments	111,757
Less: Imputed interest	88,388
Present value of operating lease liabilities	$ 23,369	$ 23,166

DEFERRED COSTS - Schedule of De

DEFERRED COSTS - Schedule of Deferred Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred Costs [Line Items]
Financing costs, Deferred Costs, net	$ 10,480
Deferred Costs, net	95,984	$ 96,639
Financing costs - Unsecured Credit Facility
Deferred Costs [Line Items]
Leasing costs, Total Cost	164,274	155,457
Financing costs, Total Cost	4,688	4,688
Total Cost	168,962	160,145
Leasing costs, Accumulated Amortization	(71,220)	(62,920)
Financing costs, Accumulated Amortization	(1,758)	(586)
Total, Accumulated Amortization	(72,978)	(63,506)
Leasing costs, Deferred Costs, net	93,054	92,537
Financing costs, Deferred Costs, net	2,930	4,102
Deferred Costs, net	$ 95,984	$ 96,639

DEFERRED COSTS - Narrative (Det

DEFERRED COSTS - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Capitalized internal direct leasing costs	$ 1.8	$ 3	$ 2.1

INTANGIBLE ASSETS AND LIABILI_3

INTANGIBLE ASSETS AND LIABILITIES - Schedule of Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Intangible assets, net:
Total Cost	$ 24,466	$ 56,213
Accumulated Amortization	(16,772)	(37,762)
Total	7,694	18,451
Intangible liabilities, net:
Total Cost	17,588	20,985
Accumulated Amortization	(9,318)	(10,663)
Total	8,270	10,322
In-place lease value
Intangible assets, net:
Total Cost	24,281	55,715
Accumulated Amortization	(16,673)	(37,437)
Total	7,608	18,278
Tenant relationship value
Intangible assets, net:
Total Cost	110	167
Accumulated Amortization	(52)	(104)
Total	58	63
Above market leases acquired
Intangible assets, net:
Total Cost	75	331
Accumulated Amortization	(47)	(221)
Total	$ 28	$ 110

INTANGIBLE ASSETS AND LIABILI_4

INTANGIBLE ASSETS AND LIABILITIES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Tenant Move Outs Prior To End Of Lease Term
Finite-Lived Intangible Assets [Line Items]
Intangible assets written off through accelerated amortization	$ 100	$ 400	$ 3,600
Tenant Move-Outs
Finite-Lived Intangible Assets [Line Items]
Intangible assets written off through accelerated amortization	$ 10	$ 100	$ 600

INTANGIBLE ASSETS AND LIABILI_5

INTANGIBLE ASSETS AND LIABILITIES - Schedule of Amortization for Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Assets
2024	$ 1,818
2025	1,485
2026	1,093
2027	808
2028	313
Thereafter	2,177
Total	7,694	$ 18,451
Liabilities
2024	929
2025	869
2026	739
2027	623
2028	534
Thereafter	4,576
Total	$ 8,270	$ 10,322

DEBT OBLIGATIONS - Schedule of

DEBT OBLIGATIONS - Schedule of Consolidated Debt Obligations (Details) - USD ($)					12 Months Ended
	Dec. 22, 2023	Mar. 01, 2023	Jan. 20, 2023	Dec. 20, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2024	Jan. 16, 2024	Sep. 30, 2023	Aug. 15, 2023	Jun. 02, 2023	Dec. 13, 2022	Nov. 23, 2022	Jun. 30, 2022
Debt Instrument [Line Items]
Principal balance outstanding					$ 2,147,434,000
Less: deferred financing costs					(10,480,000)
Plus: original issue premium (discount), net					1,878,000
Debt, net					2,138,832,000
Repayments of unsecured notes					64,164,000	$ 296,134,000	$ 0
Gain on early extinguishment of debt					138,000	(435,000)	$ 0
Secured fix rate debt
Debt Instrument [Line Items]
Debt instrument, face amount												$ 220,000,000
Principal balance outstanding					255,671,000	0
Less: deferred financing costs					(3,153,000)	0
Unsecured Debt
Debt Instrument [Line Items]
Principal balance outstanding					1,888,610,000	1,971,411,000
Less: deferred financing costs					(7,327,000)	(9,307,000)
Plus: original issue premium (discount), net					1,878,000	2,934,000
Debt, net					1,883,161,000	1,965,038,000
$245.0M 5.88% Secured Term Loan due 2028 | Secured fix rate debt
Debt Instrument [Line Items]
Debt instrument, face amount					$ 245,000,000
Debt instrument, interest rate, stated percentage					5.88%
Principal balance outstanding					$ 245,000,000	0
Effective interest rate					5.88%
$50.0M Construction Loan due 2026 | Secured fix rate debt
Debt Instrument [Line Items]
Debt instrument, face amount					$ 50,000,000						$ 50,000,000
Principal balance outstanding					$ 13,824,000	0
$50.0M Construction Loan due 2026 | Secured fix rate debt | SOFR
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage											2.50%
Effective interest rate					2.50%
Mortgage notes payable | Secured fix rate debt
Debt Instrument [Line Items]
Principal balance outstanding					$ 258,824,000	0
$600 million Unsecured Credit Facility | Unsecured Debt
Debt Instrument [Line Items]
Debt instrument, face amount					600,000,000
Principal balance outstanding					$ 0	88,500,000
$600 million Unsecured Credit Facility | Unsecured Debt | SOFR
Debt Instrument [Line Items]
Variable interest rate					1.15%
$600 million Unsecured Credit Facility | Unsecured Debt | Daily SOFR Adjustment
Debt Instrument [Line Items]
Variable interest rate					0.10%
Term Loan - Swapped to fixed | Unsecured Debt
Debt Instrument [Line Items]
Debt instrument, face amount														$ 250,000,000
Debt instrument, interest rate, stated percentage														5.01%
Principal balance outstanding					$ 250,000,000	250,000,000									$ 250,000,000
Term Loan - Swapped to fixed | Unsecured Debt | SOFR
Debt Instrument [Line Items]
Variable interest rate					1.30%
$70.0 million Term Loan | Unsecured Debt
Debt Instrument [Line Items]
Debt instrument, face amount		$ 70,000,000			$ 70,000,000
Principal balance outstanding					$ 70,000,000	0
Extension period					12 months
$70.0 million Term Loan | Unsecured Debt | SOFR
Debt Instrument [Line Items]
Variable interest rate					0.0185%
$70.0 million Term Loan | Unsecured Debt | Daily SOFR Adjustment
Debt Instrument [Line Items]
Variable interest rate		0.10%			0.10%
$350.0M 3.95% Guaranteed Notes due 2023 | Unsecured Debt
Debt Instrument [Line Items]
Debt instrument, face amount	$ 350,000,000				$ 350,000,000
Debt instrument, interest rate, stated percentage			3.95%	3.95%	3.95%
Principal balance outstanding				$ 295,700,000	$ 0	54,301,000
Effective interest rate					3.87%
Repayments of unsecured notes			$ 55,200,000
Redemption on remaining principal amount			54,300,000
Interest payable	100,000		$ 920,000	4,100,000
Debt repurchase amount	$ 10,000,000
Redemption price, percent	98.60%
Gain on early extinguishment of debt	$ 100,000			$ (400,000)
$350.0M 4.10% Guaranteed Notes due 2024 | Unsecured Debt
Debt Instrument [Line Items]
Debt instrument, face amount					$ 350,000,000
Debt instrument, interest rate, stated percentage					4.10%
Principal balance outstanding					$ 340,000,000	350,000,000
Effective interest rate					3.78%
$450.0M 3.95% Guaranteed Notes due 2027 | Unsecured Debt
Debt Instrument [Line Items]
Debt instrument, face amount					$ 450,000,000
Debt instrument, interest rate, stated percentage					3.95%
Principal balance outstanding					$ 450,000,000	450,000,000
Effective interest rate					4.03%
$350.0M 7.55% Guaranteed Notes due 2028 | Unsecured Debt
Debt Instrument [Line Items]
Debt instrument, face amount					$ 350,000,000								$ 350,000,000
Debt instrument, interest rate, stated percentage					7.55%								7.55%
Principal balance outstanding					$ 350,000,000	350,000,000
Effective interest rate					7.98%					7.80%
$350.0M 7.55% Guaranteed Notes due 2028 | Unsecured Debt | Forecast
Debt Instrument [Line Items]
Effective interest rate								8.05%
$350.0M 7.55% Guaranteed Notes due 2028 | Unsecured Debt | Basis Point Adjustment
Debt Instrument [Line Items]
Variable interest rate					0.25%
$350.0M 4.55% Guaranteed Notes due 2029 | Unsecured Debt
Debt Instrument [Line Items]
Debt instrument, face amount					$ 350,000,000
Debt instrument, interest rate, stated percentage					4.55%
Principal balance outstanding					$ 350,000,000	350,000,000
Effective interest rate					4.30%
Indenture IA (Preferred Trust I) | Unsecured Debt
Debt Instrument [Line Items]
Principal balance outstanding					$ 27,062,000	27,062,000
Indenture IA (Preferred Trust I) | Unsecured Debt | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage									5.14%
Indenture IA (Preferred Trust I) | Unsecured Debt | SOFR
Debt Instrument [Line Items]
Variable interest rate					1.51%
Indenture IB (Preferred Trust I) | Unsecured Debt
Debt Instrument [Line Items]
Principal balance outstanding					$ 25,774,000	25,774,000
Indenture IB (Preferred Trust I) | Unsecured Debt | SOFR
Debt Instrument [Line Items]
Variable interest rate					1.51%
Indenture II (Preferred Trust II) | Unsecured Debt
Debt Instrument [Line Items]
Principal balance outstanding					$ 25,774,000	$ 25,774,000
Indenture II (Preferred Trust II) | Unsecured Debt | Subsequent Event
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage									5.24%
Indenture II (Preferred Trust II) | Unsecured Debt | SOFR
Debt Instrument [Line Items]
Variable interest rate					1.51%

DEBT OBLIGATIONS - Narrative (D

DEBT OBLIGATIONS - Narrative (Details)

1 Months Ended

12 Months Ended

Dec. 22, 2023 USD ($)

Mar. 01, 2023 USD ($)

Jan. 19, 2023 USD ($) subsidiary property

Dec. 20, 2022 USD ($)

Dec. 13, 2022 USD ($)

Jun. 30, 2022 USD ($) property

Jan. 31, 2024

Dec. 31, 2023 USD ($)

Dec. 31, 2022 USD ($)

Dec. 31, 2021 USD ($)

Aug. 15, 2023 USD ($)

Jun. 02, 2023 USD ($)

Jan. 20, 2023 USD ($)

Nov. 23, 2022 USD ($)

Debt Instrument [Line Items]

Principal balance outstanding

$ 2,147,434,000

Proceeds from unsecured notes

0

$ 350,000,000

$ 0

Loss on extinguishment of debt

(138,000)

435,000

$ 0

Unsecured Debt

Debt Instrument [Line Items]

Principal balance outstanding

1,888,610,000

1,971,411,000

Secured fix rate debt

Debt Instrument [Line Items]

Debt instrument, face amount

$ 220,000,000

Principal balance outstanding

255,671,000

0

Letter of Credit

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 50,000,000

$70.0 million Term Loan | Unsecured Debt

Debt Instrument [Line Items]

Debt instrument, face amount

$ 70,000,000

70,000,000

Debt instrument, term

1 year

Principal balance outstanding

$ 70,000,000

0

$70.0 million Term Loan | Unsecured Debt | Subsequent Event

Debt Instrument [Line Items]

Debt instrument, extension term duration

12 months

$70.0 million Term Loan | Unsecured Debt | SOFR

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

0.0185%

$70.0 million Term Loan | Unsecured Debt | Secured Overnight Financing Rate (SOFR)

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

1.75%

$70.0 million Term Loan | Unsecured Debt | Daily SOFR Adjustment

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

0.10%

0.10%

$50.0M Construction Loan due 2026

Debt Instrument [Line Items]

Percent of commitment guaranteed

20%

$50.0M Construction Loan due 2026 | Secured fix rate debt

Debt Instrument [Line Items]

Debt instrument, face amount

$ 50,000,000

$ 50,000,000

Principal balance outstanding

13,824,000

0

$50.0M Construction Loan due 2026 | Secured fix rate debt | SOFR

Debt Instrument [Line Items]

Debt instrument, interest rate, stated percentage

2.50%

Term Loan - Swapped to fixed | Unsecured Debt

Debt Instrument [Line Items]

Debt instrument, face amount

$ 250,000,000

Debt instrument, interest rate, stated percentage

5.01%

Principal balance outstanding

$ 250,000,000

$ 250,000,000

250,000,000

Term Loan - Swapped to fixed | Unsecured Debt | SOFR

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

1.30%

Term Loan - Swapped to fixed | Unsecured Debt | Secured Overnight Financing Rate (SOFR) | Minimum

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

0.80%

Term Loan - Swapped to fixed | Unsecured Debt | Secured Overnight Financing Rate (SOFR) | Maximum

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

1.60%

Term Loan - Swapped to fixed | Unsecured Debt | Base Rate | Minimum

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

0%

Term Loan - Swapped to fixed | Unsecured Debt | Base Rate | Maximum

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

0.60%

Term Loan - Swapped to fixed | Line of Credit

Debt Instrument [Line Items]

Capitalized financing costs

$ 2,000,000

$600 million Unsecured Credit Facility | Unsecured Debt

Debt Instrument [Line Items]

Debt instrument, face amount

$ 600,000,000

Principal balance outstanding

$ 0

88,500,000

$600 million Unsecured Credit Facility | Unsecured Debt | SOFR

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

1.15%

$600 million Unsecured Credit Facility | Unsecured Debt | Daily SOFR Adjustment

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

0.10%

$350.0M 7.55% Guaranteed Notes due 2028 | Unsecured Debt

Debt Instrument [Line Items]

Debt instrument, face amount

$ 350,000,000

$ 350,000,000

Debt instrument, interest rate, stated percentage

7.55%

7.55%

Principal balance outstanding

$ 350,000,000

350,000,000

Percentage of face amount

99.06%

Unsecured term loan, net

$ 3,300,000

Proceeds from unsecured notes

$ 344,600,000

$350.0M 3.95% Guaranteed Notes due 2023 | Unsecured Debt

Debt Instrument [Line Items]

Debt instrument, face amount

$ 350,000,000

$ 350,000,000

Debt instrument, interest rate, stated percentage

3.95%

3.95%

3.95%

Principal balance outstanding

$ 295,700,000

$ 0

$ 54,301,000

Interest payable

100,000

4,100,000

$ 920,000

Loss on extinguishment of debt

$ (100,000)

$ 400,000

Redemption on remaining principal amount

$ 54,300,000

Secured fix rate debt | Secured Facility

Debt Instrument [Line Items]

Number of wholly owned subsidiaries participating in a loan agreement | subsidiary

7

Number of operating properties | property

7

Debt instrument, face amount

$ 245,000,000

Debt instrument, interest rate, stated percentage

5.88%

Financing costs - Unsecured Credit Facility

Debt Instrument [Line Items]

Long-term debt, weighted average interest rate

5.94%

3.04%

Interest expense borrowings

$ 600,000

$ 5,600,000

Financing costs - Unsecured Credit Facility | Line of Credit

Debt Instrument [Line Items]

Maximum borrowing capacity

600,000,000

Capitalized financing costs

4,700,000

Line of credit facility, accordion feature

$ 500,000,000

Financing costs - Unsecured Credit Facility | Line of Credit | Secured Overnight Financing Rate (SOFR) | Minimum

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

0.725%

Financing costs - Unsecured Credit Facility | Line of Credit | Secured Overnight Financing Rate (SOFR) | Maximum

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

1.40%

Financing costs - Unsecured Credit Facility | Line of Credit | Base Rate | Minimum

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

0%

Financing costs - Unsecured Credit Facility | Line of Credit | Base Rate | Maximum

Debt Instrument [Line Items]

Basis spread on interest rate (as percent)

0.40%

Financing costs - Unsecured Credit Facility | 2022 Credit Facility | Line of Credit

Debt Instrument [Line Items]

Debt instrument, extension term duration

6 months

Debt instrument, number of extensions | property

2

Line of credit facility covenant minimum fixed charge coverage ratio

1.5

Line of credit facility covenant maximum leverage ratio

0.60

Line of credit facility covenant maximum unsecured indebtedness to unencumbered asset value ratio

0.60

Line of credit facility covenant maximum secured indebtedness to asset value ratio

0.40

Line of credit facility covenant minimum unencumbered cash flow to interest expense on unsecured debt ratio

1.75

Line of credit facility covenant maximum percent of payments of dividends and distributions

0.95

DEBT OBLIGATIONS - Aggregate Sc

DEBT OBLIGATIONS - Aggregate Scheduled Principal Payments of Debt Obligation, Excluding Amortization of Discounts and Premiums (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Debt Disclosure [Abstract]
2024	$ 340,000
2025	70,000
2026	13,824
2027	700,000
2028	595,000
Thereafter	428,610
Total principal payments	2,147,434
Net unamortized premiums/(discounts)	1,878
Net deferred financing costs	(10,480)
Outstanding indebtedness	$ 2,138,832

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured term loan, net	$ 255,671	$ 0
Deferred financing costs, net	10,480
Unsecured notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred financing costs, net	7,327	9,307
Unsecured notes payable | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unsecured notes payable	1,486,052	1,549,760
Deferred financing costs, net	5,800	7,500
Unsecured notes payable | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	1,386,621	1,411,351
Variable rate debt | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Variable rate debt	410,932	415,278
Deferred financing costs, net	1,500	1,800
Variable rate debt | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	370,665	386,988
Secured fix rate debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred financing costs, net	3,153	0
Secured fix rate debt | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Secured term loan, net	241,847	0
Deferred financing costs, net	3,200	0
Secured fix rate debt | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value	$ 233,088	$ 0

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Derivatives, Fair Value [Line Items]
Derivative, notional amount	$ 250,000	$ 250,000
Swap | Cash Flow Hedging
Derivatives, Fair Value [Line Items]
Derivative asset, notional amount	250,000	0
Derivative liability, notional amount	$ 0	250,000
Strike	3.729%
Derivative asset, fair value, gross asset	$ 0	255
Derivative liability, fair value, gross liability	$ (757)	$ 0

LIMITED PARTNERS' NONCONTROLL_2

LIMITED PARTNERS' NONCONTROLLING INTERESTS IN THE PARENT COMPANY (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Noncontrolling Interest [Abstract]
Aggregate amount related to non-controlling interests classified within equity	$ 4.1	$ 4.9
Settlement value of non controlling interest in operating partnership	$ 2.8	$ 3.2

BENEFICIARIES' EQUITY OF THE _3

BENEFICIARIES' EQUITY OF THE PARENT COMPANY - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator
Net income (loss)	$ (197,403)	$ 53,992	$ 12,366
Net (income) loss attributable to noncontrolling interests, Basic	614	(168)	(77)
Net (income) loss attributable to noncontrolling interests, Diluted	614	(168)	(77)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(567)	(456)	(421)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(567)	(456)	(421)
Net income (loss) attributable to common shareholders, Basic	(197,356)	53,368	11,868
Net income (loss) attributable to common shareholders, Diluted	$ (197,356)	$ 53,368	$ 11,868
Denominator
Weighted average units outstanding, basic (in shares)	171,959,210	171,491,369	170,878,185
Contingent securities/Share based compensation (in shares)	0	834,277	1,395,055
Diluted weighted average shares outstanding (in shares)	171,959,210	172,325,646	172,273,240
Earnings (loss) per Common Share:
Net income (loss) attributable to common shareholders, Basic (in dollars per share)	$ (1.15)	$ 0.31	$ 0.07
Net income (loss) attributable to common shareholders, Diluted (in dollars per share)	$ (1.15)	$ 0.31	$ 0.07

BENEFICIARIES' EQUITY OF THE _4

BENEFICIARIES' EQUITY OF THE PARENT COMPANY - Narrative (Details) - USD ($)			12 Months Ended
	Jan. 18, 2024	Dec. 05, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 03, 2019
Class of Stock [Line Items]
Distributions declared (in dollars per share)		$ 0.15	$ 0.68	$ 0.76	$ 0.76
Dividends paid in cash (in dollars per share)			$ 0.72	$ 0.76	$ 0.76
Dividends, common stock		$ 26,000,000
Authorized amount			$ 0	$ 0		$ 150,000,000
Repurchased and retired (in shares)			0	0
Preferred shares authorized (in shares)			20,000,000	20,000,000
Preferred shares outstanding (in shares)			0	0
Subsequent Event
Class of Stock [Line Items]
Dividends paid in cash (in dollars per share)	$ 0.15
Redeemable Common Limited Partnership Units
Class of Stock [Line Items]
Redeemable common limited partnership units (in shares)			515,595	516,467	823,983

PARTNERS' EQUITY OF THE PAREN_3

PARTNERS' EQUITY OF THE PARENT COMPANY - Schedule of Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator
Net income (loss)	$ (197,403)	$ 53,992	$ 12,366
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(567)	(456)	(421)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (567)	$ (456)	$ (421)
Denominator
Weighted average units outstanding, basic (in shares)	171,959,210	171,491,369	170,878,185
Contingent securities/Share based compensation (in shares)	0	834,277	1,395,055
Weighted average shares outstanding, diluted (in shares)	171,959,210	172,325,646	172,273,240
Earnings (loss) per Common Partnership Unit:
Net income (loss) attributable to common shareholders, Basic (in dollars per share)	$ (1.15)	$ 0.31	$ 0.07
Net income (loss) attributable to common shareholders, Diluted (in dollars per share)	$ (1.15)	$ 0.31	$ 0.07
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Net income (loss)	$ (197,403)	$ 53,992	$ 12,366
Net income attributable to noncontrolling interests	22	2	3
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(567)	(456)	(421)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(567)	(456)	(421)
Net income (loss) attributable to common unitholders, Basic	(197,948)	53,538	11,948
Net income (loss) attributable to common unitholders, Diluted	$ (197,948)	$ 53,538	$ 11,948
Denominator
Weighted average units outstanding, basic (in shares)	172,475,645	172,036,481	171,770,843
Contingent securities/Share based compensation (in shares)	0	834,277	1,395,055
Weighted average shares outstanding, diluted (in shares)	172,475,645	172,870,758	173,165,898
Earnings (loss) per Common Partnership Unit:
Net income (loss) attributable to common shareholders, Basic (in dollars per share)	$ (1.15)	$ 0.31	$ 0.07
Net income (loss) attributable to common shareholders, Diluted (in dollars per share)	$ (1.15)	$ 0.31	$ 0.07

PARTNERS' EQUITY OF THE PAREN_4

PARTNERS' EQUITY OF THE PARENT COMPANY - Narrative (Details) $ / shares in Units, $ in Millions			12 Months Ended
	Jan. 18, 2024 $ / shares	Dec. 05, 2023 USD ($) $ / shares	Dec. 31, 2023 class_of_units $ / shares shares	Dec. 31, 2022 $ / shares shares	Dec. 31, 2021 $ / shares shares
Earnings Per Common Partnership Unit [Line Items]
Number of classes of partnership units | class_of_units			2
Amount of dividend declared | $		$ 26
Repurchased and retired (in shares) | shares			0	0
Dividends paid in cash (in dollars per share)			$ 0.72	$ 0.76	$ 0.76
Distributions declared (in dollars per share)		$ 0.15	0.68	0.76	0.76
Subsequent Event
Earnings Per Common Partnership Unit [Line Items]
Dividends paid in cash (in dollars per share)	$ 0.15
Class A Units
Earnings Per Common Partnership Unit [Line Items]
Redeemable limited partnership unit price (in dollars per share)			$ 5.40	$ 6.15	$ 13.42
Limited partners' capital account, units outstanding (in units) | shares			515,595	516,467	823,983
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings Per Common Partnership Unit [Line Items]
Preferred units, outstanding (in units) | shares			0	0
Amount of dividend declared | $		$ 26
Repurchase program, number of mirror unit of operating partnership retired for each common share repurchased | shares			1
Distributions declared (in dollars per share)		$ 0.15
BRANDYWINE OPERATING PARTNERSHIP, L.P. | Subsequent Event
Earnings Per Common Partnership Unit [Line Items]
Dividends paid in cash (in dollars per share)	$ 0.15

SHARE-BASED COMPENSATION, 401_3

SHARE-BASED COMPENSATION, 401(K) PLAN AND DEFERRED COMPENSATION - Narrative (Details)			12 Months Ended
	Feb. 16, 2023 installment shares	Feb. 01, 2023 shares	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares	Jan. 19, 2023 $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Defined contribution plan, maximum annual contribution per employee, percent			100%
Defined contribution plan, employer discretionary contribution amount | $			$ 700,000	$ 400,000	$ 500,000
Number of shares to be issued under deferred compensation plan included in total shares outstanding | shares			1,200,000	1,200,000
Restricted Share Rights Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares) | shares			889,166	553,893
Unrecognized compensation expenses | $			$ 1,800,000
Weighted average period over which options will be recognized			11 months 19 days
Share-based compensation expense | $			$ 4,700,000	$ 4,500,000	4,100,000
Share-based compensation expense, capitalized | $			$ 500,000	700,000	500,000
Granted (in shares) | shares	528,590		808,283
Number of restricted share right will get settled for common share | shares	1
Accumulated service period for voluntary termination (in years)	15 years
Restricted Share Rights Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			1 year
Restricted Share Rights Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	3 years		3 years
Restricted Performance Share Units Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)		3 years
Unrecognized compensation expenses | $			$ 7,500,000
Weighted average period over which options will be recognized			1 year 4 months 24 days
Share-based compensation expense | $			$ 6,900,000	6,200,000	4,300,000
Share-based compensation expense, capitalized | $			$ 900,000	$ 1,100,000	$ 500,000
Number of vesting installments | installment	3
Accelerated vesting period (in years)	1 year
Share-based compensation activity (in shares) | shares		171,318
Dividends payable (in dollars per share) | $ / shares						$ 0.19
Restricted Performance Share Units Plan | Executive Officers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards outstanding (in shares) | shares			1,941,450	884,277
Granted (in shares) | shares			1,057,173
Performance earning potential (as percent)			225%	225%	225%
Outperformance feature measurement term (in years)			3 years
Additional vesting period (in days)			366 days
Restricted Performance Share Units Plan | Executive Officers | 2023 Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $			$ 500,000
Awards issuable under outperformance feature (in shares) | shares			925,642
Restricted Performance Share Units Plan | Executive Officers | 2022 Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards issuable under outperformance feature (in shares) | shares				406,179
Restricted Performance Share Units Plan | Executive Officers | 2021 Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $			$ 0
Awards issuable under outperformance feature (in shares) | shares					388,840
Restricted Performance Share Units Plan | Non-Officer Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) | shares	92,703
Employee Share Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense | $			$ 100,000	$ 20,000	$ 100,000
Share-based compensation, percentage of closing price			85%
Maximum participant contribution, percentage of compensation			20%
Maximum participant contribution, dollar amount | $			$ 50,000
Total number of shares authorized for issuance (in shares) | shares			1,250,000
Stock issued during period, value, employee stock purchase plan | $			$ 400,000	$ 600,000	$ 600,000
Share-based compensation arrangement by share-based payment award, discount from market price, purchase			15%

SHARE-BASED COMPENSATION, 401_4

SHARE-BASED COMPENSATION, 401(K) PLAN AND DEFERRED COMPENSATION - Schedule of Company's Restricted Share Activity (Details) - Restricted Share Rights Awards - $ / shares		12 Months Ended
	Feb. 16, 2023	Dec. 31, 2023
Shares
Beginning balance (in shares)		553,893
Granted (in shares)	528,590	808,283
Vested (in shares)		(458,111)
Forfeited (in shares)		(14,899)
Ending balance (in shares)		889,166
Weighted Average Grant Date Fair Value
Non-vested, beginning balance (in dollars per share)		$ 13.22
Granted (in dollars per share)		6.03
Vested (in dollars per share)		9.29
Forfeited (in dollars per share)		8.61
Non-vested, ending balance (in dollars per share)		$ 8.79

SHARE-BASED COMPENSATION, 401_5

SHARE-BASED COMPENSATION, 401(K) PLAN AND DEFERRED COMPENSATION - Schedule of Restricted Performance Share Units Plan (Details) - Executive Officers - Restricted Performance Share Units Plan - USD ($) $ in Thousands				12 Months Ended
	Mar. 03, 2022	Mar. 05, 2021	Mar. 05, 2020	Dec. 31, 2023
Shares
Beginning balance (in shares)				884,277
Granted (in shares)				1,057,173
Units Cancelled (in shares)				0
Ending balance (in shares)				1,941,450
3/5/2021 RSPU Grant
Shares
Beginning balance (in shares)				371,239
Granted (in shares)				0
Units Cancelled (in shares)				0
Ending balance (in shares)				371,239
Granted (in shares)			380,957
Fair Value of Units on Grant Date			$ 6,389
3/3/2022 RSPU Grant
Shares
Beginning balance (in shares)				513,038
Granted (in shares)				0
Units Cancelled (in shares)				0
Ending balance (in shares)				513,038
Granted (in shares)		516,852
Fair Value of Units on Grant Date		$ 6,872
2/16/2023 RSPU Grant Date
Shares
Beginning balance (in shares)				0
Granted (in shares)				1,057,173
Units Cancelled (in shares)				0
Ending balance (in shares)				1,057,173
Granted (in shares)	1,057,173
Fair Value of Units on Grant Date	$ 7,125

DISTRIBUTIONS (Details)

DISTRIBUTIONS (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Common Share Distributions:
Ordinary income (in usd per share)	$ 0.39	$ 0.47	$ 0.64
Capital gain (in usd per share)	0.03	0.29	0.01
Non-taxable distributions (in usd per share)	0.30	0	0.11
Distributions per share (in usd per share)	$ 0.72	$ 0.76	$ 0.76
Percentage classified as ordinary income	54.40%	62.10%	83.90%
Percentage classified as capital gain	4%	37.90%	1.20%
Percentage classified as non-taxable distribution	41.60%	0%	14.90%

INCOME TAXES AND TAX CREDIT T_2

INCOME TAXES AND TAX CREDIT TRANSACTIONS (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Examination [Line Items]
Accruals for tax uncertainties	$ 0	$ 0
Deferred income tax expense	0	0	$ 0
Current income tax expense (benefit)	0	0	$ 0
Other Assets
Income Tax Examination [Line Items]
Deferred tax assets	$ 0	$ 0

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		$ 1,633,334	$ 1,701,219	$ 1,804,648
Change in fair market value during year		(4,579)	5,371	4,817
Allocation of unrealized (gains)/losses on derivative financial instruments to noncontrolling interests		14	(18)	(28)
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[1]	0	564	752
Ending balance		1,324,157	1,633,334	1,701,219
Operating Partnership
Change in fair market value during year		(4,579)	5,371	4,817
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[1]	0	564	752
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in fair market value during year		(4,579)	5,371	4,817
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[1]	0	564	752
Operating Partnership
Beginning balance		1,630,139	1,690,079	1,793,082
Change in fair market value during year		(4,579)	5,371	4,817
Amortization of interest rate contracts reclassified from comprehensive income to interest expense	[1]	0	564	752
Ending balance		1,321,372	1,630,139	1,690,079
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		3,897	(2,020)	(7,561)
Ending balance		(668)	3,897	(2,020)
Accumulated Other Comprehensive Income (Loss) | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Operating Partnership
Beginning balance		3,569	(2,366)	(7,935)
Ending balance		$ (1,010)	$ 3,569	$ (2,366)
[1] Amounts reclassified from comprehensive income to interest expense within the Consolidated Statements of Operations.

SEGMENT INFORMATION - Narrative

SEGMENT INFORMATION - Narrative (Details)	12 Months Ended
	Dec. 31, 2023 segment
Segment Reporting [Abstract]
Number of reportable segments	4

SEGMENT INFORMATION - Real Esta

SEGMENT INFORMATION - Real Estate Investments, at Cost of Company's Reportable Segments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating properties	$ 3,542,232	$ 3,617,240	$ 3,472,602
Right of use asset - operating leases, net	19,031	19,664
Construction-in-progress	135,529	218,869
Land held for development	82,510	76,499
Prepaid leasehold interests in land held for development, net	27,762	35,576
Total Core Segments | Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	3,237,096	3,248,182
Philadelphia CBD | Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	1,534,893	1,517,801
Pennsylvania Suburbs | Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	900,230	878,546
Austin, Texas | Continuing Operations
Segment Reporting Information [Line Items]
Operating properties	801,973	851,835
Other
Segment Reporting Information [Line Items]
Operating properties	$ 305,136	$ 369,058

SEGMENT INFORMATION - Net Opera

SEGMENT INFORMATION - Net Operating Income of Company's Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Total revenue	$ 514,651	$ 506,100	$ 486,819
Operating expenses	(189,947)	(194,401)	(188,311)
Net operating income	324,704	311,699	298,508
Philadelphia CBD
Segment Reporting Information [Line Items]
Total revenue		220,875
Pennsylvania Suburbs
Segment Reporting Information [Line Items]
Total revenue		128,940
Austin, Texas
Segment Reporting Information [Line Items]
Total revenue		96,329
Operating Segments | Philadelphia CBD
Segment Reporting Information [Line Items]
Total revenue	230,933	220,876	207,858
Operating expenses	(79,579)	(79,827)	(73,695)
Net operating income	151,354	141,049	134,163
Operating Segments | Pennsylvania Suburbs
Segment Reporting Information [Line Items]
Total revenue	129,300	128,940	124,566
Operating expenses	(39,584)	(41,814)	(40,011)
Net operating income	89,716	87,126	84,555
Operating Segments | Austin, Texas
Segment Reporting Information [Line Items]
Total revenue	95,505	96,328	101,680
Operating expenses	(38,453)	(41,141)	(39,374)
Net operating income	57,052	55,187	62,306
Operating Segments | Other
Segment Reporting Information [Line Items]
Total revenue	39,306	36,610	33,880
Operating expenses	(21,134)	(21,165)	(25,226)
Net operating income	18,172	15,445	8,654
Corporate
Segment Reporting Information [Line Items]
Total revenue	19,607	23,346	18,835
Operating expenses	(11,197)	(10,454)	(10,005)
Net operating income	$ 8,410	$ 12,892	$ 8,830

SEGMENT INFORMATION - Unconsoli

SEGMENT INFORMATION - Unconsolidated Real Estate Ventures of Company's Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity	$ 552,494	$ 532,224
Equity in income (loss) of real estate venture	(77,915)	(22,016)	$ (26,697)
Philadelphia CBD
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity	450,136	387,301
Equity in income (loss) of real estate venture	(25,793)	(11,764)	(15,191)
Mid-Atlantic Office JV
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity	0	31,005
Equity in income (loss) of real estate venture	(26,448)	412	932
MAP Venture
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity	(48,733)	(35,411)
Equity in income (loss) of real estate venture	(10,581)	(8,340)	(8,683)
Austin, Texas
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity	79,160	65,426
Equity in income (loss) of real estate venture	0	0	0
Other
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity	71,931	83,903
Equity in income (loss) of real estate venture	$ (15,093)	$ (2,324)	$ (3,755)

SEGMENT INFORMATION - Reconcili

SEGMENT INFORMATION - Reconciliation of Consolidated Net Income to Consolidated NOI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting [Abstract]
Net income (loss)	$ (197,403)	$ 53,992	$ 12,366
Plus:
Interest expense	95,456	68,764	62,617
Interest expense - amortization of deferred financing costs	4,369	3,091	2,836
Depreciation and amortization	188,797	177,984	178,105
General and administrative expenses	34,862	35,006	30,153
Equity in loss of unconsolidated real estate ventures	77,915	22,016	26,697
Provision for impairment	131,573	4,663	0
Gain (loss) on early extinguishment of debt	(138)	435	0
Less:
Interest and investment income	1,671	1,905	8,295
Income tax provision	(72)	(55)	(47)
Net gain on disposition of real estate	7,736	17,677	142
Net gain on sale of undepreciated real estate	1,211	8,007	2,903
Net gain on real estate venture transactions	181	26,718	2,973
Consolidated net operating income	$ 324,704	$ 311,699	$ 298,508

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands		1 Months Ended	12 Months Ended
	Oct. 21, 2020 USD ($)	Feb. 28, 2021 property	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2004 ft²
Property Subject to or Available for Operating Lease [Line Items]
Unconsolidated Real Estate Venture Debt at 100%, gross			$ 1,204,779		$ 1,412,758
Preferred Equity Investment Obligation
Property Subject to or Available for Operating Lease [Line Items]
Other commitments					15,000
Commerce Square | Preferred Equity Investment Obligation
Property Subject to or Available for Operating Lease [Line Items]
Other commitments					20,000
Amount committed to date					9,500
Drexel Square
Property Subject to or Available for Operating Lease [Line Items]
Other commitments					6,200
Estimated potential additional contribution obligation					2,200
Natural Disasters and Other Casualty Events
Property Subject to or Available for Operating Lease [Line Items]
Number of properties damaged | property		1
Write-off of fixed assets				$ 1,200
Restoration liability			800	7,200
Business interruption costs				3,900
Insurance proceeds			$ 2,800	15,300
Natural Disasters and Other Casualty Events | Other Income
Property Subject to or Available for Operating Lease [Line Items]
Insurance proceeds				3,000
Natural Disasters and Other Casualty Events | Accounts Payable and Accrued Liabilities
Property Subject to or Available for Operating Lease [Line Items]
Restoration liability				$ 1,900
Unconsolidated Real Estate Ventures
Property Subject to or Available for Operating Lease [Line Items]
Unconsolidated Real Estate Venture Debt at 100%, gross					1,412,800
Two Logan Square
Property Subject to or Available for Operating Lease [Line Items]
Rentable area (in square feet) | ft²						708,844
Settlement liabilities					$ 600
Two Logan Square | Secured fix rate debt
Property Subject to or Available for Operating Lease [Line Items]
Repayments of long-term debt	$ 79,800

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance for doubtful accounts:
Balance at Beginning of Year	$ 3,947	$ 4,133	$ 5,086
Additions	0	0	0
Deductions	1,275	186	953
Balance at End of Year	$ 2,672	$ 3,947	$ 4,133

Schedule III - Real Estate an_2

Schedule III - Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Initial Cost
Encumbrances	$ 245,000
Land	358,066
Buildings and Improvements	2,520,935
Net Improvements (Retirements) Since Acquisition	663,128
Gross Amount Which Carried
Land	394,669
Buildings and Improvements	3,147,563
Total	3,542,232	$ 3,617,240	$ 3,472,602	$ 3,474,109
Accumulated Depreciation at December 31, 2023	1,131,792	$ 1,063,060	$ 957,450	$ 896,561
PENNSYLVANIA SUBURBS | Six Tower Bridge (181 Washington Street)
Initial Cost
Encumbrances	0
Land	6,927
Buildings and Improvements	14,722
Net Improvements (Retirements) Since Acquisition	1,330
Gross Amount Which Carried
Land	6,237
Buildings and Improvements	16,742
Total	22,979
Accumulated Depreciation at December 31, 2023	5,108
PENNSYLVANIA SUBURBS | 426 Lancaster Avenue
Initial Cost
Encumbrances	0
Land	1,689
Buildings and Improvements	6,756
Net Improvements (Retirements) Since Acquisition	9,405
Gross Amount Which Carried
Land	1,686
Buildings and Improvements	16,164
Total	17,850
Accumulated Depreciation at December 31, 2023	3,841
PENNSYLVANIA SUBURBS | 640 Freedom Business Center
Initial Cost
Encumbrances	0
Land	1,015
Buildings and Improvements	20,098
Net Improvements (Retirements) Since Acquisition	4,762
Gross Amount Which Carried
Land	305
Buildings and Improvements	25,570
Total	25,875
Accumulated Depreciation at December 31, 2023	17,737
PENNSYLVANIA SUBURBS | 620 Freedom Business Center
Initial Cost
Encumbrances	0
Land	666
Buildings and Improvements	13,118
Net Improvements (Retirements) Since Acquisition	3,160
Gross Amount Which Carried
Land	199
Buildings and Improvements	16,745
Total	16,944
Accumulated Depreciation at December 31, 2023	10,756
PENNSYLVANIA SUBURBS | 1000 First Avenue
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	13,708
Net Improvements (Retirements) Since Acquisition	3,345
Gross Amount Which Carried
Land	0
Buildings and Improvements	17,053
Total	17,053
Accumulated Depreciation at December 31, 2023	13,278
PENNSYLVANIA SUBURBS | 1060 First Avenue
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	13,665
Net Improvements (Retirements) Since Acquisition	4,134
Gross Amount Which Carried
Land	0
Buildings and Improvements	17,799
Total	17,799
Accumulated Depreciation at December 31, 2023	13,769
PENNSYLVANIA SUBURBS | 630 Freedom Business Center Drive
Initial Cost
Encumbrances	0
Land	666
Buildings and Improvements	13,251
Net Improvements (Retirements) Since Acquisition	3,182
Gross Amount Which Carried
Land	201
Buildings and Improvements	16,898
Total	17,099
Accumulated Depreciation at December 31, 2023	11,422
PENNSYLVANIA SUBURBS | 1020 First Avenue
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	10,744
Net Improvements (Retirements) Since Acquisition	4,544
Gross Amount Which Carried
Land	0
Buildings and Improvements	15,288
Total	15,288
Accumulated Depreciation at December 31, 2023	11,736
PENNSYLVANIA SUBURBS | 1040 First Avenue
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	14,142
Net Improvements (Retirements) Since Acquisition	5,065
Gross Amount Which Carried
Land	0
Buildings and Improvements	19,207
Total	19,207
Accumulated Depreciation at December 31, 2023	14,973
PENNSYLVANIA SUBURBS | 610 Freedom Business Center Drive
Initial Cost
Encumbrances	0
Land	485
Buildings and Improvements	9,602
Net Improvements (Retirements) Since Acquisition	1,615
Gross Amount Which Carried
Land	146
Buildings and Improvements	11,556
Total	11,702
Accumulated Depreciation at December 31, 2023	8,089
PENNSYLVANIA SUBURBS | 650 Park Avenue
Initial Cost
Encumbrances	0
Land	1,916
Buildings and Improvements	4,378
Net Improvements (Retirements) Since Acquisition	(4,378)
Gross Amount Which Carried
Land	1,916
Buildings and Improvements	0
Total	1,916
Accumulated Depreciation at December 31, 2023	0
PENNSYLVANIA SUBURBS | 600 Park Avenue
Initial Cost
Encumbrances	0
Land	1,012
Buildings and Improvements	4,048
Net Improvements (Retirements) Since Acquisition	0
Gross Amount Which Carried
Land	1,012
Buildings and Improvements	4,048
Total	5,060
Accumulated Depreciation at December 31, 2023	2,706
PENNSYLVANIA SUBURBS | 933 First Avenue
Initial Cost
Encumbrances	15,960
Land	3,127
Buildings and Improvements	20,794
Net Improvements (Retirements) Since Acquisition	(1,125)
Gross Amount Which Carried
Land	3,127
Buildings and Improvements	19,669
Total	22,796
Accumulated Depreciation at December 31, 2023	5,692
PENNSYLVANIA SUBURBS | 500 North Gulph Road
Initial Cost
Encumbrances	16,121
Land	1,303
Buildings and Improvements	5,201
Net Improvements (Retirements) Since Acquisition	21,471
Gross Amount Which Carried
Land	1,303
Buildings and Improvements	26,672
Total	27,975
Accumulated Depreciation at December 31, 2023	5,854
PENNSYLVANIA SUBURBS | 401 Plymouth Road
Initial Cost
Encumbrances	0
Land	6,199
Buildings and Improvements	16,131
Net Improvements (Retirements) Since Acquisition	15,706
Gross Amount Which Carried
Land	6,199
Buildings and Improvements	31,837
Total	38,036
Accumulated Depreciation at December 31, 2023	16,202
PENNSYLVANIA SUBURBS | Metroplex (4000 Chemical Road)
Initial Cost
Encumbrances	16,055
Land	4,373
Buildings and Improvements	24,546
Net Improvements (Retirements) Since Acquisition	5,554
Gross Amount Which Carried
Land	4,373
Buildings and Improvements	30,100
Total	34,473
Accumulated Depreciation at December 31, 2023	11,076
PENNSYLVANIA SUBURBS | Metroplex II
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	0
Net Improvements (Retirements) Since Acquisition	569
Gross Amount Which Carried
Land	0
Buildings and Improvements	569
Total	569
Accumulated Depreciation at December 31, 2023	6
PENNSYLVANIA SUBURBS | Metroplex III
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	0
Net Improvements (Retirements) Since Acquisition	317
Gross Amount Which Carried
Land	0
Buildings and Improvements	317
Total	317
Accumulated Depreciation at December 31, 2023	4
PENNSYLVANIA SUBURBS | 610 West Germantown Pike
Initial Cost
Encumbrances	0
Land	3,651
Buildings and Improvements	14,514
Net Improvements (Retirements) Since Acquisition	254
Gross Amount Which Carried
Land	3,051
Buildings and Improvements	15,368
Total	18,419
Accumulated Depreciation at December 31, 2023	7,768
PENNSYLVANIA SUBURBS | 600 West Germantown Pike
Initial Cost
Encumbrances	0
Land	3,652
Buildings and Improvements	15,288
Net Improvements (Retirements) Since Acquisition	(415)
Gross Amount Which Carried
Land	3,052
Buildings and Improvements	15,473
Total	18,525
Accumulated Depreciation at December 31, 2023	7,992
PENNSYLVANIA SUBURBS | 630 West Germantown Pike
Initial Cost
Encumbrances	0
Land	3,558
Buildings and Improvements	14,743
Net Improvements (Retirements) Since Acquisition	(673)
Gross Amount Which Carried
Land	2,973
Buildings and Improvements	14,655
Total	17,628
Accumulated Depreciation at December 31, 2023	7,757
PENNSYLVANIA SUBURBS | 620 West Germantown Pike
Initial Cost
Encumbrances	0
Land	3,572
Buildings and Improvements	14,435
Net Improvements (Retirements) Since Acquisition	1,156
Gross Amount Which Carried
Land	2,985
Buildings and Improvements	16,178
Total	19,163
Accumulated Depreciation at December 31, 2023	7,802
PENNSYLVANIA SUBURBS | 660 West Germantown Pike
Initial Cost
Encumbrances	0
Land	3,694
Buildings and Improvements	5,487
Net Improvements (Retirements) Since Acquisition	14,871
Gross Amount Which Carried
Land	4,517
Buildings and Improvements	19,535
Total	24,052
Accumulated Depreciation at December 31, 2023	7,784
PENNSYLVANIA SUBURBS | 351 Plymouth Road
Initial Cost
Encumbrances	0
Land	1,043
Buildings and Improvements	555
Net Improvements (Retirements) Since Acquisition	0
Gross Amount Which Carried
Land	1,043
Buildings and Improvements	555
Total	1,598
Accumulated Depreciation at December 31, 2023	260
PENNSYLVANIA SUBURBS | 150 Radnor Chester Road
Initial Cost
Encumbrances	0
Land	11,925
Buildings and Improvements	36,986
Net Improvements (Retirements) Since Acquisition	22,327
Gross Amount Which Carried
Land	11,897
Buildings and Improvements	59,341
Total	71,238
Accumulated Depreciation at December 31, 2023	30,253
PENNSYLVANIA SUBURBS | One Radnor Corporate Center
Initial Cost
Encumbrances	0
Land	7,323
Buildings and Improvements	28,613
Net Improvements (Retirements) Since Acquisition	4,133
Gross Amount Which Carried
Land	7,323
Buildings and Improvements	32,746
Total	40,069
Accumulated Depreciation at December 31, 2023	19,410
PENNSYLVANIA SUBURBS | 201 King of Prussia Road
Initial Cost
Encumbrances	0
Land	8,956
Buildings and Improvements	29,811
Net Improvements (Retirements) Since Acquisition	4,939
Gross Amount Which Carried
Land	8,949
Buildings and Improvements	34,757
Total	43,706
Accumulated Depreciation at December 31, 2023	24,432
PENNSYLVANIA SUBURBS | 555 Lancaster Avenue
Initial Cost
Encumbrances	0
Land	8,014
Buildings and Improvements	16,508
Net Improvements (Retirements) Since Acquisition	12,652
Gross Amount Which Carried
Land	8,609
Buildings and Improvements	28,565
Total	37,174
Accumulated Depreciation at December 31, 2023	10,733
PENNSYLVANIA SUBURBS | Four Radnor Corporate Center
Initial Cost
Encumbrances	0
Land	5,406
Buildings and Improvements	21,390
Net Improvements (Retirements) Since Acquisition	6,719
Gross Amount Which Carried
Land	5,705
Buildings and Improvements	27,810
Total	33,515
Accumulated Depreciation at December 31, 2023	16,857
PENNSYLVANIA SUBURBS | Five Radnor Corporate Center
Initial Cost
Encumbrances	0
Land	6,506
Buildings and Improvements	25,525
Net Improvements (Retirements) Since Acquisition	9,676
Gross Amount Which Carried
Land	6,578
Buildings and Improvements	35,129
Total	41,707
Accumulated Depreciation at December 31, 2023	17,511
PENNSYLVANIA SUBURBS | Three Radnor Corporate Center
Initial Cost
Encumbrances	0
Land	4,773
Buildings and Improvements	17,961
Net Improvements (Retirements) Since Acquisition	2,740
Gross Amount Which Carried
Land	4,791
Buildings and Improvements	20,683
Total	25,474
Accumulated Depreciation at December 31, 2023	12,840
PENNSYLVANIA SUBURBS | Two Radnor Corporate Center
Initial Cost
Encumbrances	0
Land	3,937
Buildings and Improvements	15,484
Net Improvements (Retirements) Since Acquisition	5,195
Gross Amount Which Carried
Land	3,942
Buildings and Improvements	20,674
Total	24,616
Accumulated Depreciation at December 31, 2023	11,281
PENNSYLVANIA SUBURBS | 130 Radnor Chester Road
Initial Cost
Encumbrances	0
Land	2,573
Buildings and Improvements	8,338
Net Improvements (Retirements) Since Acquisition	(258)
Gross Amount Which Carried
Land	2,567
Buildings and Improvements	8,086
Total	10,653
Accumulated Depreciation at December 31, 2023	4,324
PENNSYLVANIA SUBURBS | 170 Radnor Chester Road
Initial Cost
Encumbrances	0
Land	2,514
Buildings and Improvements	8,147
Net Improvements (Retirements) Since Acquisition	2,344
Gross Amount Which Carried
Land	2,509
Buildings and Improvements	10,496
Total	13,005
Accumulated Depreciation at December 31, 2023	5,860
PENNSYLVANIA SUBURBS | 101 West Elm Street
Initial Cost
Encumbrances	0
Land	6,251
Buildings and Improvements	25,209
Net Improvements (Retirements) Since Acquisition	2,600
Gross Amount Which Carried
Land	6,251
Buildings and Improvements	27,809
Total	34,060
Accumulated Depreciation at December 31, 2023	13,040
PENNSYLVANIA SUBURBS | 1 West Elm Street
Initial Cost
Encumbrances	0
Land	3,557
Buildings and Improvements	14,249
Net Improvements (Retirements) Since Acquisition	9,139
Gross Amount Which Carried
Land	3,557
Buildings and Improvements	23,388
Total	26,945
Accumulated Depreciation at December 31, 2023	8,417
PENNSYLVANIA SUBURBS | 250 King of Prussia Road
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	20,566
Net Improvements (Retirements) Since Acquisition	65,182
Gross Amount Which Carried
Land	11,200
Buildings and Improvements	74,548
Total	85,748
Accumulated Depreciation at December 31, 2023	4,666
PHILADELPHIA CBD | 3001-3003 JFK Boulevard
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	0
Net Improvements (Retirements) Since Acquisition	85
Gross Amount Which Carried
Land	0
Buildings and Improvements	85
Total	85
Accumulated Depreciation at December 31, 2023	38
PHILADELPHIA CBD | Cira Centre (2929 Arch Street)
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	208,570
Net Improvements (Retirements) Since Acquisition	38,189
Gross Amount Which Carried
Land	12,586
Buildings and Improvements	234,173
Total	246,759
Accumulated Depreciation at December 31, 2023	82,593
PHILADELPHIA CBD | Three Logan Square (1717 Arch Street)
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	98,188
Net Improvements (Retirements) Since Acquisition	87,145
Gross Amount Which Carried
Land	25,195
Buildings and Improvements	160,138
Total	185,333
Accumulated Depreciation at December 31, 2023	68,452
PHILADELPHIA CBD | One Logan Square (130 North 18th Street)
Initial Cost
Encumbrances	0
Land	14,496
Buildings and Improvements	107,736
Net Improvements (Retirements) Since Acquisition	23,882
Gross Amount Which Carried
Land	14,473
Buildings and Improvements	131,641
Total	146,114
Accumulated Depreciation at December 31, 2023	75,119
PHILADELPHIA CBD | Two Logan Square (100 North 18th Street)
Initial Cost
Encumbrances	0
Land	16,066
Buildings and Improvements	100,255
Net Improvements (Retirements) Since Acquisition	34,756
Gross Amount Which Carried
Land	16,066
Buildings and Improvements	135,011
Total	151,077
Accumulated Depreciation at December 31, 2023	67,090
PHILADELPHIA CBD | Cira Centre South Garage (129 South 30th Street)
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	76,008
Net Improvements (Retirements) Since Acquisition	26,881
Gross Amount Which Carried
Land	6,549
Buildings and Improvements	96,340
Total	102,889
Accumulated Depreciation at December 31, 2023	30,503
PHILADELPHIA CBD | 1900 Market Street
Initial Cost
Encumbrances	61,703
Land	7,768
Buildings and Improvements	17,263
Net Improvements (Retirements) Since Acquisition	61,721
Gross Amount Which Carried
Land	7,768
Buildings and Improvements	78,984
Total	86,752
Accumulated Depreciation at December 31, 2023	35,534
PHILADELPHIA CBD | 3020 Market Street
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	21,417
Net Improvements (Retirements) Since Acquisition	6,005
Gross Amount Which Carried
Land	0
Buildings and Improvements	27,422
Total	27,422
Accumulated Depreciation at December 31, 2023	13,339
PHILADELPHIA CBD | 618-634 Market Street
Initial Cost
Encumbrances	0
Land	13,365
Buildings and Improvements	5,791
Net Improvements (Retirements) Since Acquisition	5,161
Gross Amount Which Carried
Land	13,365
Buildings and Improvements	10,952
Total	24,317
Accumulated Depreciation at December 31, 2023	7,610
PHILADELPHIA CBD | FMC Tower at Cira Centre South (2929 Walnut Street)
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	400,294
Net Improvements (Retirements) Since Acquisition	10,819
Gross Amount Which Carried
Land	0
Buildings and Improvements	411,113
Total	411,113
Accumulated Depreciation at December 31, 2023	100,935
PHILADELPHIA CBD | 2100 Market Street
Initial Cost
Encumbrances	0
Land	18,827
Buildings and Improvements	0
Net Improvements (Retirements) Since Acquisition	6,318
Gross Amount Which Carried
Land	18,854
Buildings and Improvements	6,291
Total	25,145
Accumulated Depreciation at December 31, 2023	2,715
PHILADELPHIA CBD | 1505-11 Race Street
Initial Cost
Encumbrances	0
Land	3,662
Buildings and Improvements	6,061
Net Improvements (Retirements) Since Acquisition	8
Gross Amount Which Carried
Land	3,670
Buildings and Improvements	6,061
Total	9,731
Accumulated Depreciation at December 31, 2023	480
PHILADELPHIA CBD | 3000 Market Street
Initial Cost
Encumbrances	0
Land	18,924
Buildings and Improvements	13,080
Net Improvements (Retirements) Since Acquisition	17,349
Gross Amount Which Carried
Land	18,924
Buildings and Improvements	30,429
Total	49,353
Accumulated Depreciation at December 31, 2023	4,739
PHILADELPHIA CBD | The Bulletin Building (3025 Market Street)
Initial Cost
Encumbrances	49,429
Land	0
Buildings and Improvements	24,377
Net Improvements (Retirements) Since Acquisition	44,435
Gross Amount Which Carried
Land	0
Buildings and Improvements	68,812
Total	68,812
Accumulated Depreciation at December 31, 2023	15,078
AUSTIN, TX | 401-405 Colorado Street
Initial Cost
Encumbrances	62,688
Land	0
Buildings and Improvements	106,828
Net Improvements (Retirements) Since Acquisition	564
Gross Amount Which Carried
Land	0
Buildings and Improvements	107,392
Total	107,392
Accumulated Depreciation at December 31, 2023	5,958
AUSTIN, TX | 11501 Burnet Road - Building 1
Initial Cost
Encumbrances	0
Land	3,755
Buildings and Improvements	22,702
Net Improvements (Retirements) Since Acquisition	4
Gross Amount Which Carried
Land	3,755
Buildings and Improvements	22,706
Total	26,461
Accumulated Depreciation at December 31, 2023	11,689
AUSTIN, TX | 11501 Burnet Road - Building 2
Initial Cost
Encumbrances	0
Land	2,732
Buildings and Improvements	16,305
Net Improvements (Retirements) Since Acquisition	733
Gross Amount Which Carried
Land	2,732
Buildings and Improvements	17,038
Total	19,770
Accumulated Depreciation at December 31, 2023	8,991
AUSTIN, TX | 11501 Burnet Road - Building 3
Initial Cost
Encumbrances	0
Land	3,688
Buildings and Improvements	22,348
Net Improvements (Retirements) Since Acquisition	7,118
Gross Amount Which Carried
Land	3,688
Buildings and Improvements	29,466
Total	33,154
Accumulated Depreciation at December 31, 2023	13,671
AUSTIN, TX | 11501 Burnet Road - Building 4
Initial Cost
Encumbrances	0
Land	2,614
Buildings and Improvements	15,740
Net Improvements (Retirements) Since Acquisition	3
Gross Amount Which Carried
Land	2,614
Buildings and Improvements	15,743
Total	18,357
Accumulated Depreciation at December 31, 2023	8,105
AUSTIN, TX | 11501 Burnet Road - Building 5
Initial Cost
Encumbrances	0
Land	3,689
Buildings and Improvements	22,354
Net Improvements (Retirements) Since Acquisition	4
Gross Amount Which Carried
Land	3,689
Buildings and Improvements	22,358
Total	26,047
Accumulated Depreciation at December 31, 2023	11,511
AUSTIN, TX | 11501 Burnet Road - Building 6
Initial Cost
Encumbrances	0
Land	2,676
Buildings and Improvements	15,972
Net Improvements (Retirements) Since Acquisition	14,114
Gross Amount Which Carried
Land	2,676
Buildings and Improvements	30,086
Total	32,762
Accumulated Depreciation at December 31, 2023	16,346
AUSTIN, TX | 11501 Burnet Road - Building 8
Initial Cost
Encumbrances	0
Land	1,400
Buildings and Improvements	7,422
Net Improvements (Retirements) Since Acquisition	1,776
Gross Amount Which Carried
Land	1,400
Buildings and Improvements	9,198
Total	10,598
Accumulated Depreciation at December 31, 2023	4,742
AUSTIN, TX | 11501 Burnet Road - Parking Garage
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	19,826
Net Improvements (Retirements) Since Acquisition	1,588
Gross Amount Which Carried
Land	0
Buildings and Improvements	21,414
Total	21,414
Accumulated Depreciation at December 31, 2023	11,364
AUSTIN, TX | Four Points Centre 3, 11120 Four Points Drive
Initial Cost
Encumbrances	23,044
Land	1,140
Buildings and Improvements	0
Net Improvements (Retirements) Since Acquisition	40,322
Gross Amount Which Carried
Land	1,141
Buildings and Improvements	40,321
Total	41,462
Accumulated Depreciation at December 31, 2023	8,637
AUSTIN, TX | One Barton Skyway (1501 South MoPac Expressway)
Initial Cost
Encumbrances	0
Land	10,496
Buildings and Improvements	47,670
Net Improvements (Retirements) Since Acquisition	8,189
Gross Amount Which Carried
Land	10,495
Buildings and Improvements	55,860
Total	66,355
Accumulated Depreciation at December 31, 2023	8,647
AUSTIN, TX | Two Barton Skyway (1601 South MoPac Expressway)
Initial Cost
Encumbrances	0
Land	10,849
Buildings and Improvements	53,868
Net Improvements (Retirements) Since Acquisition	3,784
Gross Amount Which Carried
Land	10,848
Buildings and Improvements	57,653
Total	68,501
Accumulated Depreciation at December 31, 2023	9,099
AUSTIN, TX | Four Barton Skyway (1301 South MoPac Expressway)
Initial Cost
Encumbrances	0
Land	13,301
Buildings and Improvements	57,041
Net Improvements (Retirements) Since Acquisition	7,895
Gross Amount Which Carried
Land	13,300
Buildings and Improvements	64,937
Total	78,237
Accumulated Depreciation at December 31, 2023	9,367
AUSTIN, TX | Four Points Centre (11305 Four Points Drive)
Initial Cost
Encumbrances	0
Land	7,800
Buildings and Improvements	43,581
Net Improvements (Retirements) Since Acquisition	4,622
Gross Amount Which Carried
Land	7,800
Buildings and Improvements	48,203
Total	56,003
Accumulated Depreciation at December 31, 2023	7,977
AUSTIN, TX | River Place - Building 1 (6500 River Place Boulevard)
Initial Cost
Encumbrances	0
Land	2,004
Buildings and Improvements	17,680
Net Improvements (Retirements) Since Acquisition	990
Gross Amount Which Carried
Land	2,004
Buildings and Improvements	18,670
Total	20,674
Accumulated Depreciation at December 31, 2023	2,822
AUSTIN, TX | River Place - Building 2 (6500 River Place Boulevard)
Initial Cost
Encumbrances	0
Land	3,137
Buildings and Improvements	29,254
Net Improvements (Retirements) Since Acquisition	1,508
Gross Amount Which Carried
Land	3,137
Buildings and Improvements	30,762
Total	33,899
Accumulated Depreciation at December 31, 2023	4,338
AUSTIN, TX | River Place - Building 3 (6500 River Place Boulevard)
Initial Cost
Encumbrances	0
Land	3,064
Buildings and Improvements	26,705
Net Improvements (Retirements) Since Acquisition	1,195
Gross Amount Which Carried
Land	3,064
Buildings and Improvements	27,900
Total	30,964
Accumulated Depreciation at December 31, 2023	3,753
AUSTIN, TX | River Place - Building 4 (6500 River Place Boulevard
Initial Cost
Encumbrances	0
Land	2,273
Buildings and Improvements	18,617
Net Improvements (Retirements) Since Acquisition	1,140
Gross Amount Which Carried
Land	2,273
Buildings and Improvements	19,757
Total	22,030
Accumulated Depreciation at December 31, 2023	2,684
AUSTIN, TX | River Place - Building 5 (6500 River Place Boulevard)
Initial Cost
Encumbrances	0
Land	1,752
Buildings and Improvements	14,315
Net Improvements (Retirements) Since Acquisition	736
Gross Amount Which Carried
Land	1,752
Buildings and Improvements	15,051
Total	16,803
Accumulated Depreciation at December 31, 2023	2,218
AUSTIN, TX | River Place - Building 6 (6500 River Place Boulevard)
Initial Cost
Encumbrances	0
Land	1,598
Buildings and Improvements	12,945
Net Improvements (Retirements) Since Acquisition	703
Gross Amount Which Carried
Land	1,598
Buildings and Improvements	13,648
Total	15,246
Accumulated Depreciation at December 31, 2023	2,044
AUSTIN, TX | River Place - Building 7 (6500 River Place Boulevard)
Initial Cost
Encumbrances	0
Land	1,801
Buildings and Improvements	16,486
Net Improvements (Retirements) Since Acquisition	1,374
Gross Amount Which Carried
Land	1,801
Buildings and Improvements	17,860
Total	19,661
Accumulated Depreciation at December 31, 2023	3,146
AUSTIN, TX | Quarry Lake II (4516 Seton Center Parkway)
Initial Cost
Encumbrances	0
Land	3,970
Buildings and Improvements	30,546
Net Improvements (Retirements) Since Acquisition	1,678
Gross Amount Which Carried
Land	3,867
Buildings and Improvements	32,327
Total	36,194
Accumulated Depreciation at December 31, 2023	4,541
Other | 6600 Rockledge Drive
Initial Cost
Encumbrances	0
Land	0
Buildings and Improvements	37,421
Net Improvements (Retirements) Since Acquisition	(14,597)
Gross Amount Which Carried
Land	0
Buildings and Improvements	22,824
Total	22,824
Accumulated Depreciation at December 31, 2023	9,299
Other | 1676 International Drive
Initial Cost
Encumbrances	0
Land	18,437
Buildings and Improvements	97,538
Net Improvements (Retirements) Since Acquisition	(30,581)
Gross Amount Which Carried
Land	10,239
Buildings and Improvements	75,155
Total	85,394
Accumulated Depreciation at December 31, 2023	22,630
Other | 8260 Greensboro Drive
Initial Cost
Encumbrances	0
Land	7,952
Buildings and Improvements	33,964
Net Improvements (Retirements) Since Acquisition	10,969
Gross Amount Which Carried
Land	8,102
Buildings and Improvements	44,783
Total	52,885
Accumulated Depreciation at December 31, 2023	15,881
Other | 2340 Dulles Corner Boulevard
Initial Cost
Encumbrances	0
Land	16,345
Buildings and Improvements	65,379
Net Improvements (Retirements) Since Acquisition	(23,353)
Gross Amount Which Carried
Land	9,747
Buildings and Improvements	48,624
Total	58,371
Accumulated Depreciation at December 31, 2023	1,192
Other | Dabney Land Westwood
Initial Cost
Encumbrances	0
Land	1,732
Buildings and Improvements	0
Net Improvements (Retirements) Since Acquisition	3,690
Gross Amount Which Carried
Land	819
Buildings and Improvements	4,706
Total	5,525
Accumulated Depreciation at December 31, 2023	493
Other | Main Street-Plaza 1000
Initial Cost
Encumbrances	0
Land	2,732
Buildings and Improvements	10,942
Net Improvements (Retirements) Since Acquisition	284
Gross Amount Which Carried
Land	2,732
Buildings and Improvements	11,226
Total	13,958
Accumulated Depreciation at December 31, 2023	11,073
Other | Main Street-Piazza
Initial Cost
Encumbrances	0
Land	696
Buildings and Improvements	2,802
Net Improvements (Retirements) Since Acquisition	2,762
Gross Amount Which Carried
Land	704
Buildings and Improvements	5,556
Total	6,260
Accumulated Depreciation at December 31, 2023	4,042
Other | Main Street-Promenade
Initial Cost
Encumbrances	0
Land	532
Buildings and Improvements	2,052
Net Improvements (Retirements) Since Acquisition	265
Gross Amount Which Carried
Land	532
Buildings and Improvements	2,317
Total	2,849
Accumulated Depreciation at December 31, 2023	1,599
Other | 920 North King Street
Initial Cost
Encumbrances	0
Land	6,141
Buildings and Improvements	21,140
Net Improvements (Retirements) Since Acquisition	7,272
Gross Amount Which Carried
Land	6,141
Buildings and Improvements	28,412
Total	34,553
Accumulated Depreciation at December 31, 2023	17,591
Other | 300 Delaware Avenue
Initial Cost
Encumbrances	0
Land	6,369
Buildings and Improvements	13,739
Net Improvements (Retirements) Since Acquisition	2,386
Gross Amount Which Carried
Land	6,366
Buildings and Improvements	16,128
Total	22,494
Accumulated Depreciation at December 31, 2023	$ 10,881

Schedule III - Real Estate an_3

Schedule III - Real Estate and Accumulated Depreciation - Reconciliations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Balance at the Beginning of the Year	$ 3,617,240	$ 3,472,602	$ 3,474,109
Additions:
Acquisitions	0	0	0
Capital expenditures and assets placed into service	210,226	212,874	134,931
Less:
Dispositions/impairments/placed into redevelopment	(251,190)	(32,951)	(82,247)
Retirements	(34,044)	(35,285)	(54,191)
Balance at the end of the year	3,542,232	3,617,240	3,472,602
Per consolidated balance sheet	3,542,232	3,617,240	3,472,602
Tax basis of assets, cost for income tax purposes	3,000,000	3,200,000
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Balance at the beginning of the year	1,063,060	957,450	896,561
Additions:
Depreciation expense	158,194	147,735	136,171
Less:
Dispositions/impairments/placed into redevelopment	(55,969)	(7,341)	(24,440)
Retirements	(33,493)	(34,784)	(50,842)
Balance at the end of the year	1,131,792	1,063,060	957,450
Per consolidated balance sheet	$ 1,131,792	$ 1,063,060	$ 957,450
Leashold Interest Land
Less:
Lease agreement term (in years)	99 years
Maximum
Less:
Useful life (in years)	55 years