Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Cash flows from operating activities:
Net income	$ 34,529	$ 135,472	$ 121,177
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	210,005	176,000	180,323
Amortization of deferred financing costs	2,768	2,498	2,435
Amortization of debt discount/(premium), net	189	702	1,569
Amortization of stock compensation costs	6,876	5,716	4,883
Straight-line rent income	(11,369)	(12,283)	(27,115)
Amortization of acquired above (below) market leases, net	(8,857)	(3,344)	(3,071)
Ground rent expense	1,470	431	164
Provision for doubtful accounts	(1,345)	1,775	2,207
Net gain on real estate venture transactions	(11,639)	(142,233)	(80,526)
Gain on promoted interest in unconsolidated real estate venture	0	(28,283)	0
Net gain on sale of interests in real estate	(2,376)	(5,972)	(32,970)
Loss on early extinguishment of debt	0	105	3,933
Provision for impairment	0	71,707	3,057
Other than temporary impairment	0	4,076	4,844
Income from Real Estate Ventures, net of distributions	10,242	12,871	3,462
Income tax provision (benefit)	12	423	(628)
Income tax provision (benefit)
Accounts receivable	(248)	3,524	(6,266)
Other assets	9,368	(14,334)	1,752
Accounts payable and accrued expenses	(5,599)	12,579	4,004
Deferred income, gains and rent	9,319	3,017	(1,482)
Other liabilities	(9,115)	2,902	829
Net cash provided by operating activities	234,230	227,349	182,581
Cash flows from investing activities:
Acquisition of properties	0	(196,625)	(72,523)
Acquisition of partners interest in consolidated real estate venture	(2,181)	0	0
Proceeds from the sale of properties	41,795	324,090	171,860
Proceeds from real estate venture sales	9,730	60,346	145,416
Issuance of mortgage note receivable	0	(175,172)	0
Proceeds from repayment of mortgage notes receivable	3,341	192	151
Proceeds from repayment of a capital lease	0	181	0
Capital expenditures for tenant improvements	(67,258)	(65,264)	(60,586)
Capital expenditures for redevelopments	(53,846)	(48,231)	(34,679)
Capital expenditures for developments	(77,192)	(99,104)	(66,915)
Advances for the purchase of tenant assets, net of repayments	(1,035)	410	18
Investment in unconsolidated Real Estate Ventures	(253)	(908)	(6,638)
Deposits for real estate	(4,181)	(8,234)	573
Escrowed cash	0	5,694	0
Capital distributions from Real Estate Ventures	35,906	6,526	20,781
Leasing costs paid	(15,485)	(18,407)	(17,657)
Net cash provided by (used in) investing activities	(130,659)	(214,506)	79,801
Cash flows from financing activities:
Repayments of mortgage notes payable	(7,595)	(122,180)	(4,931)
Proceeds from credit facility borrowings	348,500	455,500	341,000
Repayments of credit facility borrowings	(441,000)	(363,000)	(341,000)
Proceeds from unsecured notes	216,373	0	550,131
Repayments of unsecured notes	0	0	(628,590)
Debt financing costs paid	(1,965)	(3,430)	(4,727)
Redemption of preferred shares	0	0	(100,000)
Proceeds from the exercise of stock options	3,771	0	1,229
Proceeds from the issuance of common shares	0	416	51,225
Shares used for employee taxes upon vesting of share awards	(1,554)	(1,494)	(674)
Partner contributions to consolidated real estate venture	27	16	85
Partner distributions from consolidated real estate venture	0	(94)	(48)
Repurchase and retirement of common shares	(17,282)	(21,841)	0
Redemption of limited partnership units	0	(7,043)	0
Distributions paid to shareholders	(134,140)	(128,859)	(116,311)
Distributions to noncontrolling interest	(747)	(1,065)	(947)
Net cash used in financing activities	(35,612)	(193,074)	(253,558)
Increase/(Decrease) in cash and cash equivalents and restricted cash	67,959	(180,231)	8,824
Cash and cash equivalents, beginning of period	22,842	202,179	193,919
Restricted cash, beginning of period	369	1,263	699
Cash and cash equivalents and restricted cash at beginning of year	23,211	203,442	194,618
Cash and cash equivalents, end of period	90,499	22,842	202,179
Restricted cash, end of period	671	369	1,263
Cash and cash equivalents and restricted cash at end of period	91,170	23,211	203,442
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the years ended December 31, 2019, 2018 and 2017 of $2,246, $3,586, and $3,527, respectively	66,508	76,858	83,139
Cash paid for income taxes	1,385	405	225
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	33,815	33,632	32,456
Change in construction-in-progress related to non-cash disposition of land	0	27,231	0
Change in deferred income, gains and rent to the non-cash disposition of land	0	(29,780)	0
Change in investment in real estate ventures as a result of dispositions	1,806	14,169	(64,792)
Change in Notes receivable as a result of a noncash acquisition of an operating property	0	130,742	0
Change in real estate ventures as a result of other than temporary impairment	0	(4,076)	(4,844)
Change in operating real estate related to a non-cash acquisition of an operating property	0	(20,653)	0
Change in intangible assets, net related to non-cash acquisition of an operating property	0	(3,144)	0
Change in acquired lease intangibles, net related to non-cash acquisition of an operating property	0	182	0
Change in investments in joint venture related to non-cash acquisition of property	0	(16,832)	0
Change in mortgage notes payable related to acquisition of an operating property	0	9,940	0
Change in capital expenditures financed through accounts payable at period end	(10,618)	8,784	(6,593)
Change in capital expenditures financed through retention payable at period end	(946)	(2,912)	(159)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Cash flows from operating activities:
Net income	34,529	135,472	121,177
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	210,005	176,000	180,323
Amortization of deferred financing costs	2,768	2,498	2,435
Amortization of debt discount/(premium), net	189	702	1,569
Amortization of stock compensation costs	6,876	5,716	4,883
Straight-line rent income	(11,369)	(12,283)	(27,115)
Amortization of acquired above (below) market leases, net	(8,857)	(3,344)	(3,071)
Ground rent expense	1,470	431	164
Provision for doubtful accounts	(1,345)	1,775	2,207
Net gain on real estate venture transactions	(11,639)	(142,233)	(80,526)
Gain on promoted interest in unconsolidated real estate venture	0	(28,283)	0
Net gain on sale of interests in real estate	(2,376)	(5,972)	(32,970)
Loss on early extinguishment of debt	0	105	3,933
Provision for impairment	0	71,707	3,057
Other than temporary impairment	0	4,076	4,844
Income from Real Estate Ventures, net of distributions	10,242	12,871	3,462
Income tax provision (benefit)	12	423	(628)
Income tax provision (benefit)
Accounts receivable	(248)	3,524	(6,266)
Other assets	9,368	(14,334)	1,752
Accounts payable and accrued expenses	(5,599)	12,579	4,004
Deferred income, gains and rent	9,319	3,017	(1,482)
Other liabilities	(9,115)	2,902	829
Net cash provided by operating activities	234,230	227,349	182,581
Cash flows from investing activities:
Acquisition of properties	0	(196,625)	(72,523)
Acquisition of partners interest in consolidated real estate venture	(2,181)	0	0
Proceeds from the sale of properties	41,795	324,090	171,860
Proceeds from real estate venture sales	9,730	60,346	145,416
Issuance of mortgage note receivable	0	(175,172)	0
Proceeds from repayment of mortgage notes receivable	3,341	192	151
Proceeds from repayment of a capital lease	0	181	0
Capital expenditures for tenant improvements	(67,258)	(65,264)	(60,586)
Capital expenditures for redevelopments	(53,846)	(48,231)	(34,679)
Capital expenditures for developments	(77,192)	(99,104)	(66,915)
Advances for the purchase of tenant assets, net of repayments	(1,035)	410	18
Investment in unconsolidated Real Estate Ventures	(253)	(908)	(6,638)
Deposits for real estate	(4,181)	(8,234)	573
Escrowed cash	0	5,694	0
Capital distributions from Real Estate Ventures	35,906	6,526	20,781
Leasing costs paid	(15,485)	(18,407)	(17,657)
Net cash provided by (used in) investing activities	(130,659)	(214,506)	79,801
Cash flows from financing activities:
Repayments of mortgage notes payable	(7,595)	(122,180)	(4,931)
Proceeds from credit facility borrowings	348,500	455,500	341,000
Repayments of credit facility borrowings	(441,000)	(363,000)	(341,000)
Proceeds from unsecured notes	216,373	0	550,131
Repayments of unsecured notes	0	0	(628,590)
Debt financing costs paid	(1,965)	(3,430)	(4,727)
Redemption of preferred shares	0	0	(100,000)
Proceeds from the exercise of stock options	3,771	0	1,229
Proceeds from the issuance of common shares	0	416	51,225
Shares used for employee taxes upon vesting of share awards	(1,554)	(1,494)	(674)
Partner contributions to consolidated real estate venture	27	16	85
Partner distributions from consolidated real estate venture	0	(94)	(48)
Repurchase and retirement of common shares	(17,282)	(21,841)	0
Redemption of limited partnership units	0	(7,043)	0
Distributions paid to shareholders	(134,887)	(129,924)	(117,258)
Net cash used in financing activities	(35,612)	(193,074)	(253,558)
Increase/(Decrease) in cash and cash equivalents and restricted cash	67,959	(180,231)	8,824
Cash and cash equivalents, beginning of period	22,842	202,179	193,919
Restricted cash, beginning of period	369	1,263	699
Cash and cash equivalents and restricted cash at beginning of year	23,211	203,442	194,618
Cash and cash equivalents, end of period	90,499	22,842	202,179
Restricted cash, end of period	671	369	1,263
Cash and cash equivalents and restricted cash at end of period	91,170	23,211	203,442
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the years ended December 31, 2019, 2018 and 2017 of $2,246, $3,586, and $3,527, respectively	66,508	76,858	83,139
Cash paid for income taxes	1,385	405	225
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	33,815	33,632	32,456
Change in construction-in-progress related to non-cash disposition of land	0	27,231	0
Change in deferred income, gains and rent to the non-cash disposition of land	0	(29,780)	0
Change in investment in real estate ventures as a result of dispositions	1,806	14,169	(64,792)
Change in Notes receivable as a result of a noncash acquisition of an operating property	0	130,742	0
Change in real estate ventures as a result of other than temporary impairment	0	(4,076)	(4,844)
Change in intangible assets, net related to non-cash acquisition of an operating property	0	(3,144)	0
Change in acquired lease intangibles, net related to non-cash acquisition of an operating property	0	182	0
Change in investments in joint venture related to non-cash acquisition of property	0	(16,832)	0
Change in mortgage notes payable related to acquisition of an operating property	0	9,940	0
Change in capital expenditures financed through accounts payable at period end	(10,618)	8,784	(6,593)
Change in capital expenditures financed through retention payable at period end	(946)	(2,912)	(159)
Change in operating real estate related to a non-cash acquisition of an operating property	$ 0	$ (20,653)	$ 0