Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 137,289	$ 121,859	$ 40,501
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	174,259	179,357	189,676
Amortization of deferred financing costs	2,498	2,435	2,696
Amortization of debt discount/(premium), net	702	1,569	1,471
Amortization of stock compensation costs	5,716	4,883	4,310
Straight-line rent income	(12,283)	(27,115)	(28,351)
Amortization of acquired above (below) market leases, net	(3,344)	(3,071)	(6,529)
Straight-line ground rent expense	355	88	88
Provision for doubtful accounts	1,775	2,207	1,865
Net gain on real estate venture transactions	(142,233)	(80,526)	(20,000)
Gain on promoted interest	(28,283)	0	0
Net gain on sale of interests in real estate	(5,972)	(32,610)	(126,215)
Loss on early extinguishment of debt	105	3,933	66,590
Provision for impairment	71,707	3,057	40,517
Other than temporary impairment	4,076	4,844	0
Loss from Real Estate Ventures, net of distributions	12,871	3,462	12,125
Deferred financing obligation	0	0	(679)
Income tax benefit (provision)	423	(628)	0
Changes in assets and liabilities:
Accounts receivable	3,524	(6,266)	2,373
Other assets	(14,334)	1,752	544
Accounts payable and accrued expenses	12,579	4,004	(8,004)
Deferred income, gains and rent	3,017	(1,482)	137
Other liabilities	2,902	829	685
Net cash provided by operating activities	227,349	182,581	173,800
Cash flows from investing activities:
Acquisition of properties	(196,625)	(72,523)	(20,406)
Proceeds from the sale of properties	324,090	171,860	784,331
Proceeds from real estate venture sales	60,346	145,416	21,022
Issuance of mortgage notes receivable	(175,172)	0	(3,380)
Proceeds from repayment of mortgage notes receivable	192	151	0
Proceeds from repayment of a capital lease	181	0	0
Capital expenditures for tenant improvements	(65,264)	(60,586)	(51,398)
Capital expenditures for redevelopments	(48,231)	(34,679)	(11,909)
Capital expenditures for developments	(99,104)	(66,915)	(191,184)
Advances for the purchase of tenant assets, net of repayments	410	18	(784)
Investment in unconsolidated Real Estate Ventures	(908)	(6,638)	(28,610)
Deposits for real estate	(8,234)	573	(746)
Escrowed cash	5,694	0	6,992
Capital distributions from Real Estate Ventures	6,526	20,781	13,065
Leasing costs paid	(18,407)	(17,657)	(16,083)
Net cash (used in) provided by investing activities	(214,506)	79,801	500,910
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	0	86,900
Repayments of mortgage notes payable	(122,180)	(4,931)	(357,151)
Proceeds from credit facility borrowings	455,500	341,000	195,000
Repayments of credit facility borrowings	(363,000)	(341,000)	(195,000)
Proceeds from unsecured notes	0	550,131	0
Repayments of unsecured notes	0	(628,590)	(149,919)
Debt financing costs paid	(3,430)	(4,727)	(495)
Redemption of preferred shares	0	(100,000)	0
Proceeds from the exercise of stock options	0	1,229	1,286
Proceeds from the issuance of common shares	416	51,225	0
Shares used for employee taxes upon vesting of share awards	(1,494)	(674)	(879)
Partner contributions to consolidated real estate venture	16	85	108
Partner distributions from consolidated real estate venture	(94)	(48)	0
Repurchase and retirement of common shares	(21,841)	0	0
Redemption of limited partnership units	(7,043)	0	0
Distributions paid to shareholders	(128,859)	(116,311)	(115,702)
Distributions to noncontrolling interest	(1,065)	(947)	(934)
Net cash used in financing activities	(193,074)	(253,558)	(536,786)
Decrease in cash and cash equivalents and restricted cash	(180,231)	8,824	137,924
Cash and cash equivalents and restricted cash at beginning of year	203,442	194,618	56,694
Cash and cash equivalents and restricted cash at end of period	23,211	203,442	194,618
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the twelve months ended December 31, 2018, 2017 and of $3,586, $3,527 and $12,835, respectively	76,858	83,139	97,843
Cash paid for income taxes	405	225	0
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	33,632	32,456	30,032
Change in construction-in-progress related to non-cash disposition of land	27,231	0	0
Change in deferred income, gains and rent to the non-cash disposition of land	(29,780)	0	0
Change in investment in real estate ventures as a result of dispositions	14,169	(64,792)	(2,023)
Change in Notes receivable as a result of a noncash acquisition of an operating property	130,742	0	25,165
Change in real estate ventures as a result of other than temporary impairment	(4,076)	(4,844)	0
Change in operating real estate from deconsolidation of 3141 Fairview Park Drive	0	0	44,313
Change in investment in real estate ventures from deconsolidation of 3141 Fairview Park Drive	0	0	(12,642)
Change in mortgage notes payable from deconsolidation of 3141 Fairview Park Drive	0	0	(20,582)
Change in other liabilities from deconsolidation of 3141 Fairview Park Drive	0	0	(12,384)
Change in operating real estate related to a non-cash acquisition of an operating property	(20,653)	0	0
Change in intangible assets, net related to non-cash acquisition of an operating property	(3,144)	0	0
Change in acquired lease intangibles, net related to non-cash acquisition of an operating property	182	0	0
Change in investments in joint venture related to non-cash acquisition of property	(16,832)	0	0
Change in mortgage notes payable related to acquisition of an operating property	9,940	0	0
Change in capital expenditures financed through accounts payable at period end	8,784	(6,593)	8,222
Change in capital expenditures financed through retention payable at period end	(2,912)	(159)	848
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Cash flows from operating activities:
Net income	137,289	121,859	40,501
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	174,259	179,357	189,676
Amortization of deferred financing costs	2,498	2,435	2,696
Amortization of debt discount/(premium), net	702	1,569	1,471
Amortization of stock compensation costs	5,716	4,883	4,310
Straight-line rent income	(12,283)	(27,115)	(28,351)
Amortization of acquired above (below) market leases, net	(3,344)	(3,071)	(6,529)
Straight-line ground rent expense	355	88	88
Provision for doubtful accounts	1,775	2,207	1,865
Net gain on real estate venture transactions	(142,233)	(80,526)	(20,000)
Gain on promoted interest	(28,283)	0	0
Net gain on sale of interests in real estate	(5,972)	(32,610)	(126,215)
Loss on early extinguishment of debt	105	3,933	66,590
Provision for impairment	71,707	3,057	40,517
Other than temporary impairment	4,076	4,844	0
Loss from Real Estate Ventures, net of distributions	12,871	3,462	12,125
Deferred financing obligation	0	0	(679)
Income tax benefit (provision)	423	(628)	0
Changes in assets and liabilities:
Accounts receivable	3,524	(6,266)	2,373
Other assets	(14,334)	1,752	544
Accounts payable and accrued expenses	12,579	4,004	(8,004)
Deferred income, gains and rent	3,017	(1,482)	137
Other liabilities	2,902	829	685
Net cash provided by operating activities	227,349	182,581	173,800
Cash flows from investing activities:
Acquisition of properties	(196,625)	(72,523)	(20,406)
Proceeds from the sale of properties	324,090	171,860	784,331
Proceeds from real estate venture sales	60,346	145,416	21,022
Issuance of mortgage notes receivable	(175,172)	0	(3,380)
Proceeds from repayment of mortgage notes receivable	192	151	0
Proceeds from repayment of a capital lease	181	0	0
Capital expenditures for tenant improvements	(65,264)	(60,586)	(51,398)
Capital expenditures for redevelopments	(48,231)	(34,679)	(11,909)
Capital expenditures for developments	(99,104)	(66,915)	(191,184)
Advances for the purchase of tenant assets, net of repayments	410	18	(784)
Investment in unconsolidated Real Estate Ventures	(908)	(6,638)	(28,610)
Deposits for real estate	(8,234)	573	(746)
Escrowed cash	5,694	0	6,992
Capital distributions from Real Estate Ventures	6,526	20,781	13,065
Leasing costs paid	(18,407)	(17,657)	(16,083)
Net cash (used in) provided by investing activities	(214,506)	79,801	500,910
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	0	86,900
Repayments of mortgage notes payable	(122,180)	(4,931)	(357,151)
Proceeds from credit facility borrowings	455,500	341,000	195,000
Repayments of credit facility borrowings	(363,000)	(341,000)	(195,000)
Proceeds from unsecured notes	0	550,131	0
Repayments of unsecured notes	0	(628,590)	(149,919)
Debt financing costs paid	(3,430)	(4,727)	(495)
Redemption of preferred shares	0	(100,000)	0
Proceeds from the exercise of stock options	0	1,229	1,286
Proceeds from the issuance of common shares	416	51,225	0
Shares used for employee taxes upon vesting of share awards	(1,494)	(674)	(879)
Partner contributions to consolidated real estate venture	16	85	108
Partner distributions from consolidated real estate venture	(94)	(48)	0
Repurchase and retirement of common shares	(21,841)	0	0
Redemption of limited partnership units	(7,043)	0	0
Distributions paid to shareholders	(129,924)	(117,258)	(116,636)
Net cash used in financing activities	(193,074)	(253,558)	(536,786)
Decrease in cash and cash equivalents and restricted cash	(180,231)	8,824	137,924
Cash and cash equivalents and restricted cash at beginning of year	203,442	194,618	56,694
Cash and cash equivalents and restricted cash at end of period	23,211	203,442	194,618
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the twelve months ended December 31, 2018, 2017 and of $3,586, $3,527 and $12,835, respectively	76,858	83,139	97,843
Cash paid for income taxes	405	225	0
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	33,632	32,456	30,032
Change in construction-in-progress related to non-cash disposition of land	27,231	0	0
Change in deferred income, gains and rent to the non-cash disposition of land	(29,780)	0	0
Change in investment in real estate ventures as a result of dispositions	14,169	(64,792)	(2,023)
Change in Notes receivable as a result of a noncash acquisition of an operating property	130,742	0	25,162
Change in real estate ventures as a result of other than temporary impairment	(4,076)	(4,844)	0
Change in operating real estate from deconsolidation of 3141 Fairview Park Drive	0	0	44,313
Change in investment in real estate ventures from deconsolidation of 3141 Fairview Park Drive	0	0	(12,642)
Change in mortgage notes payable from deconsolidation of 3141 Fairview Park Drive	0	0	(20,582)
Change in other liabilities from deconsolidation of 3141 Fairview Park Drive	0	0	(12,384)
Change in operating real estate related to a non-cash acquisition of an operating property	(20,653)	0	0
Change in intangible assets, net related to non-cash acquisition of an operating property	(3,144)	0	0
Change in acquired lease intangibles, net related to non-cash acquisition of an operating property	182	0	0
Change in investments in joint venture related to non-cash acquisition of property	(16,832)	0	0
Change in mortgage notes payable related to acquisition of an operating property	9,940	0	0
Change in capital expenditures financed through accounts payable at period end	8,784	(6,593)	8,222
Change in capital expenditures financed through retention payable at period end	$ (2,912)	$ (159)	$ 848