Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Cash flows from operating activities:
Net income (loss)	$ 121,859	$ 40,501	$ (30,740)
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	179,357	189,676	219,029
Amortization of deferred financing costs	2,435	2,696	4,557
Amortization of debt discount/(premium), net	1,569	1,471	(755)
Amortization of stock compensation costs	4,883	4,310	5,065
Settlement of hedge transaction	0	0	(5,266)
Straight-line rent income	(27,115)	(28,351)	(23,668)
Amortization of acquired above (below) market leases, net	(3,071)	(6,529)	(7,960)
Straight-line ground rent expense	88	88	88
Provision for doubtful accounts	2,207	1,865	2,489
Net gain on real estate venture transactions	(80,526)	(20,000)	(7,418)
Net gain on sale of interests in real estate	(32,610)	(126,215)	(23,515)
Preacquisition cost write-off	0	0	1,299
Net gain from remeasurement of investment in real estate ventures	0	0	(758)
Loss on early extinguishment of debt	3,933	66,590	0
Provision for impairment	3,057	40,517	82,208
Tax credit transaction income	0	0	(19,955)
Other than temporary impairment	4,844	0	0
Real Estate Venture loss in excess of distributions	3,462	12,125	2,034
Deferred financing obligation	0	(679)	(1,237)
Income tax benefit	(628)	0	0
Changes in assets and liabilities:
Accounts receivable	(6,266)	2,373	(848)
Other assets	1,188	(155)	837
Accounts payable and accrued expenses	4,004	(8,004)	4,083
Deferred income, gains and rent	(1,482)	137	(521)
Other liabilities	829	685	(1,894)
Net cash provided by operating activities	182,017	173,101	197,154
Cash flows from investing activities:
Acquisition of properties	(72,523)	(20,406)	(150,472)
Acquisition of property - 1031 exchange funds applied	0	0	(62,812)
Proceeds from the sale of properties	171,860	784,331	247,228
Sale of property - 1031 exchange funds held in escrow	0	0	62,800
Net proceeds from the contribution of properties to an unconsolidated real estate venture	0	0	50,158
Proceeds from real estate venture sales	145,416	21,022	6,100
Issuance of mortgage note receivable	0	(3,380)	0
Proceeds from repayment of mortgage notes receivable	151	0	88,000
Capital expenditures for tenant improvements	(60,586)	(51,398)	(97,851)
Capital expenditures for redevelopments	(34,679)	(11,909)	(48,367)
Capital expenditures for developments	(66,915)	(191,184)	(179,927)
Advances for the purchase of tenant assets, net of repayments	18	(784)	308
Investment in unconsolidated Real Estate Ventures	(6,638)	(28,610)	(68,549)
Deposits for real estate	573	(746)	(878)
Escrowed cash	0	6,992	516
Cash distribution from unconsolidated Real Estate Ventures in excess of cumulative equity income	20,781	13,065	8,557
Leasing costs paid	(17,657)	(16,083)	(21,263)
Net cash provided by (used in) investing activities	79,801	500,910	(166,452)
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	86,900	130,000
Repayments of mortgage notes payable	(4,931)	(357,151)	(222,836)
Proceeds from unsecured term loan borrowing	0	0	50,000
Proceeds from credit facility borrowings	341,000	195,000	89,000
Repayments of credit facility borrowings	(341,000)	(195,000)	(89,000)
Proceeds from unsecured notes	550,131	0	0
Repayments of unsecured notes	(628,590)	(149,919)	0
Debt financing costs paid	(4,727)	(495)	(5,202)
Net proceeds from issuance of common shares\units	51,225	0	0
Redemption of preferred shares	(100,000)	0	0
Proceeds from the exercise of stock options	1,229	1,286	127
Shares used for employee taxes upon vesting of share awards	(674)	(879)	(2,055)
Partner contributions to consolidated real estate venture	85	108	1,025
Partner distributions from consolidated real estate venture	(48)	0	0
Repurchase and retirement of common shares	0	0	(67,320)
Distributions paid to shareholders	(116,311)	(115,702)	(114,328)
Distributions to noncontrolling interest	(947)	(934)	(921)
Net cash used in financing activities	(253,558)	(536,786)	(231,510)
Increase (decrease) in cash and cash equivalents	8,260	137,225	(200,808)
Cash and cash equivalents at beginning of year	193,919	56,694	257,502
Cash and cash equivalents at end of period	202,179	193,919	56,694
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the years ended December 31, 2017, 2016 and 2015 of $3,527, $12,835 and $12,150, respectively	83,139	97,843	124,953
Cash paid for income taxes	225	0	0
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	32,456	30,032	28,249
Change in investment in real estate ventures as a result of dispositions	(64,792)	(2,023)	0
Change in investment in real estate ventures related to non-cash disposition of property	0	25,165	(25,127)
Change in operating real estate related to non-cash property disposition	0	0	25,127
Change in real estate investments related to non-cash property acquisition	0	0	(66,324)
Change in investments in joint venture related to non-cash acquisition of property	0	0	66,324
Change in other liabilities from contingent consideration related to a business combination	0	0	1,585
Change in operating real estate from contingent consideration related to a business combination	0	0	(1,585)
Change in other liabilities from a deferred payment related to an asset acquisition	0	0	2,000
Change in operating real estate from a deferred payment related to an asset acquisition	0	0	(2,000)
Change in real estate ventures as a result of other than temporary impairment	(4,844)	0	0
Change in operating real estate from deconsolidation of 3141 Fairview Park Drive	0	44,313	0
Change in investment in real estate ventures from deconsolidation of 3141 Fairview Park Drive	0	(12,642)	0
Change in mortgage notes payable from deconsolidation of 3141 Fairview Park Drive	0	(20,582)	0
Change in other liabilities from deconsolidation of 3141 Fairview Park Drive	0	(12,384)	0
Change in capital expenditures financed through accounts payable at period end	(6,953)	8,222	(7,654)
Change in capital expenditures financed through retention payable at period end	(159)	848	6,104
Change in unfunded tenant allowance	0	0	(273)
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Cash flows from operating activities:
Net income (loss)	121,859	40,501	(30,740)
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	179,357	189,676	219,029
Amortization of deferred financing costs	2,435	2,696	4,557
Amortization of debt discount/(premium), net	1,569	1,471	(755)
Amortization of stock compensation costs	4,883	4,310	5,065
Settlement of hedge transaction	0	0	(5,266)
Straight-line rent income	(27,115)	(28,351)	(23,668)
Amortization of acquired above (below) market leases, net	(3,071)	(6,529)	(7,960)
Straight-line ground rent expense	88	88	88
Provision for doubtful accounts	2,207	1,865	2,489
Net gain on real estate venture transactions	(80,526)	(20,000)	(7,418)
Net gain on sale of interests in real estate	(32,610)	(126,215)	(23,515)
Preacquisition cost write-off	0	0	1,299
Net gain from remeasurement of investment in real estate ventures	0	0	(758)
Loss on early extinguishment of debt	3,933	66,590	0
Provision for impairment	3,057	40,517	82,208
Tax credit transaction income	0	0	(19,955)
Other than temporary impairment	4,844	0	0
Real Estate Venture loss in excess of distributions	3,462	12,125	2,034
Deferred financing obligation	0	(679)	(1,237)
Income tax benefit	(628)	0	0
Changes in assets and liabilities:
Accounts receivable	(6,266)	2,373	(848)
Other assets	1,188	(155)	837
Accounts payable and accrued expenses	4,004	(8,004)	4,083
Deferred income, gains and rent	(1,482)	137	(521)
Other liabilities	829	685	(1,894)
Net cash provided by operating activities	182,017	173,101	197,154
Cash flows from investing activities:
Acquisition of properties	(72,523)	(20,406)	(150,472)
Acquisition of property - 1031 exchange funds applied	0	0	(62,812)
Proceeds from the sale of properties	171,860	784,331	247,228
Sale of property - 1031 exchange funds held in escrow	0	0	62,800
Net proceeds from the contribution of properties to an unconsolidated real estate venture	0	0	50,158
Proceeds from real estate venture sales	145,416	21,022	6,100
Issuance of mortgage note receivable	0	(3,380)	0
Proceeds from repayment of mortgage notes receivable	151	0	88,000
Capital expenditures for tenant improvements	(60,586)	(51,398)	(97,851)
Capital expenditures for redevelopments	(34,679)	(11,909)	(48,367)
Capital expenditures for developments	(66,915)	(191,184)	(179,927)
Advances for the purchase of tenant assets, net of repayments	18	(784)	308
Investment in unconsolidated Real Estate Ventures	(6,638)	(28,610)	(68,549)
Deposits for real estate	573	(746)	(878)
Escrowed cash	0	6,992	516
Cash distribution from unconsolidated Real Estate Ventures in excess of cumulative equity income	20,781	13,065	8,557
Leasing costs paid	(17,657)	(16,083)	(21,263)
Net cash provided by (used in) investing activities	79,801	500,910	(166,452)
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	86,900	130,000
Repayments of mortgage notes payable	(4,931)	(357,151)	(222,836)
Proceeds from unsecured term loan borrowing	0	0	50,000
Proceeds from credit facility borrowings	341,000	195,000	89,000
Repayments of credit facility borrowings	(341,000)	(195,000)	(89,000)
Proceeds from unsecured notes	550,131	0	0
Repayments of unsecured notes	(628,590)	(149,919)	0
Debt financing costs paid	(4,727)	(495)	(5,202)
Net proceeds from issuance of common shares\units	51,225	0	0
Redemption of preferred shares	(100,000)	0	0
Proceeds from the exercise of stock options	1,229	1,286	127
Shares used for employee taxes upon vesting of share awards	(674)	(879)	(2,055)
Partner contributions to consolidated real estate venture	85	108	1,025
Partner distributions from consolidated real estate venture	(48)	0	0
Repurchase and retirement of common shares	0	0	(67,320)
Distributions paid to shareholders	(117,258)	(116,636)	(115,249)
Net cash used in financing activities	(253,558)	(536,786)	(231,510)
Increase (decrease) in cash and cash equivalents	8,260	137,225	(200,808)
Cash and cash equivalents at beginning of year	193,919	56,694	257,502
Cash and cash equivalents at end of period	202,179	193,919	56,694
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the years ended December 31, 2017, 2016 and 2015 of $3,527, $12,835 and $12,150, respectively	83,139	97,843	124,953
Cash paid for income taxes	225	0	0
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	32,456	30,032	28,249
Change in investment in real estate ventures as a result of dispositions	(64,792)	(2,023)	0
Change in investment in real estate ventures related to non-cash disposition of property	0	25,165	(25,127)
Change in operating real estate related to non-cash property disposition	0	0	25,127
Change in real estate investments related to non-cash property acquisition	0	0	(66,324)
Change in investments in joint venture related to non-cash acquisition of property	0	0	66,324
Change in other liabilities from contingent consideration related to a business combination	0	0	1,585
Change in operating real estate from contingent consideration related to a business combination	0	0	(1,585)
Change in other liabilities from a deferred payment related to an asset acquisition	0	0	2,000
Change in operating real estate from a deferred payment related to an asset acquisition	0	0	(2,000)
Change in real estate ventures as a result of other than temporary impairment	(4,844)	0	0
Change in operating real estate from deconsolidation of 3141 Fairview Park Drive	0	44,313	0
Change in investment in real estate ventures from deconsolidation of 3141 Fairview Park Drive	0	(12,642)	0
Change in mortgage notes payable from deconsolidation of 3141 Fairview Park Drive	0	(20,582)	0
Change in other liabilities from deconsolidation of 3141 Fairview Park Drive	0	(12,384)	0
Change in capital expenditures financed through accounts payable at period end	(6,953)	8,222	(7,654)
Change in capital expenditures financed through retention payable at period end	(159)	848	6,104
Change in unfunded tenant allowance	$ 0	$ 0	$ (273)