Brandywine Operating Partnership 10-Q 24 Oct 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document - shares	9 Months Ended
	Sep. 30, 2017	Oct. 20, 2017
Document Information [Line Items]
Entity Registrant Name	BRANDYWINE REALTY TRUST
Trading Symbol	BDN
Entity Central Index Key	790,816
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		175,477,498
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Document Information [Line Items]
Entity Registrant Name	BRANDYWINE OPERATING PARTNERSHIP, L.P.
Entity Central Index Key	1,060,386
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Real estate investments:
Operating properties	$ 3,769,067	$ 3,586,295
Accumulated depreciation	(885,438)	(852,476)
Operating real estate investments, net	2,883,629	2,733,819
Construction-in-progress	127,141	297,462
Land held for development	120,696	150,970
Total real estate investments, net	3,131,466	3,182,251
Assets held for sale, net	31,125	41,718
Cash and cash equivalents	25,287	193,919
Accounts receivable, net of allowance of $3,294 and $2,373 as of September 30, 2017 and December 31, 2016, respectively	14,785	12,446
Accrued rent receivable, net of allowance of $13,731 and $13,743 as of September 30, 2017 and December 31, 2016, respectively	166,093	149,624
Investment in Real Estate Ventures, equity method	236,313	281,331
Deferred costs, net	96,980	91,342
Intangible assets, net	58,817	72,478
Other assets	94,553	74,104
Total assets	3,855,419	4,099,213
LIABILITIES AND EQUITY
Mortgage notes payable, net	318,317	321,549
Unsecured credit facility	178,000	0
Unsecured term loans, net	248,347	248,099
Unsecured senior notes, net	1,144,976	1,443,464
Accounts payable and accrued expenses	112,413	103,404
Distributions payable	28,391	30,032
Deferred income, gains and rent	41,468	31,620
Acquired lease intangibles, net	17,156	18,119
Liabilities related to assets held for sale	269	81
Other liabilities	15,512	19,408
Total liabilities	2,104,849	2,215,776
Commitments and contingencies
Equity:
6.90% Series E Preferred Shares, $0.01 par value; issued and outstanding- 0 as of September 30, 2017 and 4,000,000 as of December 31, 2016	0	40
Common Shares of Brandywine Realty Trust's beneficial interest, $0.01 par value; shares authorized 400,000,000; 175,477,498 and 175,140,760 issued and outstanding as of September 30, 2017 and December 31, 2016, respectively	1,755	1,752
Additional paid-in-capital	3,167,481	3,258,870
Deferred compensation payable in common shares	14,090	13,684
Common shares in grantor trust, 1,000,966 as of September 30, 2017, 899,457 as of December 31, 2016	(14,090)	(13,684)
Cumulative earnings	586,954	539,319
Accumulated other comprehensive loss	(906)	(1,745)
Cumulative distributions	(2,021,568)	(1,931,892)
Total Brandywine Realty Trust's equity	1,733,716	1,866,344
Non-controlling interests	16,854	17,093
Total beneficiaries' equity	1,750,570	1,883,437
Total liabilities and beneficiaries' equity	3,855,419	4,099,213
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Operating properties	3,769,067	3,586,295
Accumulated depreciation	(885,438)	(852,476)
Operating real estate investments, net	2,883,629	2,733,819
Construction-in-progress	127,141	297,462
Land held for development	120,696	150,970
Total real estate investments, net	3,131,466	3,182,251
Assets held for sale, net	31,125	41,718
Cash and cash equivalents	25,287	193,919
Accounts receivable, net of allowance of $3,294 and $2,373 as of September 30, 2017 and December 31, 2016, respectively	14,785	12,446
Accrued rent receivable, net of allowance of $13,731 and $13,743 as of September 30, 2017 and December 31, 2016, respectively	166,093	149,624
Investment in Real Estate Ventures, equity method	236,313	281,331
Deferred costs, net	96,980	91,342
Intangible assets, net	58,817	72,478
Other assets	94,553	74,104
Total assets	3,855,419	4,099,213
LIABILITIES AND EQUITY
Mortgage notes payable, net	318,317	321,549
Unsecured credit facility	178,000	0
Unsecured term loans, net	248,347	248,099
Unsecured senior notes, net	1,144,976	1,443,464
Accounts payable and accrued expenses	112,413	103,404
Distributions payable	28,391	30,032
Deferred income, gains and rent	41,468	31,620
Acquired lease intangibles, net	17,156	18,119
Liabilities related to assets held for sale	269	81
Other liabilities	15,512	19,408
Total liabilities	2,104,849	2,215,776
Commitments and contingencies
Redeemable limited partnership units at redemption value; 1,479,799 issued and outstanding in as of September 30, 2017 and December 31, 2016	25,864	23,795
Equity:
6.90% Series E Preferred Shares, $0.01 par value; issued and outstanding- 0 as of September 30, 2017 and 4,000,000 as of December 31, 2016	0	96,850
General Partnership Capital; 175,477,498 and 175,140,760 units issued and outstanding as of September 30, 2017 and December 31, 2016, respectively	1,723,767	1,762,764
Accumulated other comprehensive loss	(1,276)	(2,122)
Total Brandywine Operating Partnership, L.P.'s equity	1,722,491	1,857,492
Non-controlling interest - consolidated real estate ventures	2,215	2,150
Total partners' equity	1,724,706	1,859,642
Total liabilities and beneficiaries' equity	$ 3,855,419	$ 4,099,213

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Accounts receivable, allowance	$ 3,294	$ 2,373
Accrued rent receivable, allowance	$ 13,731	$ 13,743
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Dividend Rate, Percentage	6.90%	6.90%
Preferred Stock, Par or Stated Value Per Share (USD per share)	$ 0.01	$ 0.01
Preferred Stock, Shares Issued	0	4,000,000
Preferred Stock, Shares Outstanding	0	4,000,000
Common Stock, Par or Stated Value Per Share (USD per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	400,000,000	400,000,000
Common Stock, Shares, Issued	175,477,498	175,140,760
Common Stock, Shares, Outstanding	175,477,498	175,140,760
Common Shares in Grantor Trust	1,000,966	899,457
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Accounts receivable, allowance	$ 3,294	$ 2,373
Accrued rent receivable, allowance	$ 13,731	$ 13,743
Preferred Stock, Dividend Rate, Percentage	6.90%	6.90%
Preferred Stock, Shares Issued	0	4,000,000
Preferred Stock, Shares Outstanding	0	4,000,000
Redeemable Limited Partnership Units Issued	1,479,799	1,479,799
Redeemable Limited Partnership Units Outstanding	1,479,799	1,479,799
General Partners' Capital Account, Units Issued	175,477,498	175,140,760
General Partners' Capital Account, Units Outstanding	175,477,498	175,140,760

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue
Rents	$ 102,557	$ 104,537	$ 307,446	$ 318,324
Tenant reimbursements	17,239	17,324	53,812	53,315
Termination fees	200	611	2,013	1,459
Third party management fees, labor reimbursement and leasing	6,918	6,248	20,483	17,691
Other	1,524	974	3,395	2,588
Total revenue	128,438	129,694	387,149	393,377
Operating expenses
Property operating expenses	36,847	37,250	110,947	114,208
Real estate taxes	11,235	11,566	34,062	34,933
Third party management expenses	2,619	2,501	7,391	7,172
Depreciation and amortization	42,429	46,956	132,584	142,736
General and administrative expenses	5,813	5,515	21,797	20,711
Provision for impairment	0	0	3,057	13,069
Total operating expenses	98,943	103,788	309,838	332,829
Operating income	29,495	25,906	77,311	60,548
Other income (expense)
Interest income	79	291	635	970
Interest expense	(19,732)	(20,814)	(61,473)	(64,334)
Interest expense - amortization of deferred financing costs	(577)	(645)	(1,807)	(2,063)
Interest expense - financing obligation	0	(156)	0	(679)
Equity in loss of Real Estate Ventures	(5,723)	(7,254)	(5,387)	(9,323)
Net gain (loss) on disposition of real estate	0	(104)	8,411	114,625
Net gain on sale of undepreciated real estate	953	188	953	188
Net gain on Real Estate Venture transactions	13,758	10,472	28,340	19,529
Loss on early extinguishment of debt	0	0	0	(66,590)
Net income before income taxes	18,253	7,884	46,983	52,871
Income tax benefit	793	0	1,032	0
Net income	19,046	7,884	48,015	52,871
Net income from continuing operations attributable to non-controlling interests - consolidated real estate ventures	(170)	(58)	(384)	(425)
Net income attributable to non-controlling interests	(170)	(58)	(384)	(425)
Net income attributable to Brandywine Realty Trust	18,876	7,826	47,631	52,446
Distribution to preferred shareholders	0	(1,725)	(2,032)	(5,175)
Preferred share redemption charge	0	0	(3,181)	0
Nonforfeitable dividends allocated to unvested restricted shareholders	(73)	(79)	(245)	(263)
Net income attributable to Common Shareholders of Brandywine Realty Trust	$ 18,803	$ 6,022	$ 42,173	$ 47,008
Basic income per Common Share	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Diluted income per Common Share	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Basic weighted average shares outstanding	175,433,657	175,127,110	175,315,581	174,976,998
Diluted weighted average shares outstanding	176,835,022	176,364,615	176,599,332	176,009,822
Distributions declared per Common Share	$ 0.16	$ 0.16	$ 0.48	$ 0.47
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Revenue
Rents	$ 102,557	$ 104,537	$ 307,446	$ 318,324
Tenant reimbursements	17,239	17,324	53,812	53,315
Termination fees	200	611	2,013	1,459
Third party management fees, labor reimbursement and leasing	6,918	6,248	20,483	17,691
Other	1,524	974	3,395	2,588
Total revenue	128,438	129,694	387,149	393,377
Operating expenses
Property operating expenses	36,847	37,250	110,947	114,208
Real estate taxes	11,235	11,566	34,062	34,933
Third party management expenses	2,619	2,501	7,391	7,172
Depreciation and amortization	42,429	46,956	132,584	142,736
General and administrative expenses	5,813	5,515	21,797	20,711
Provision for impairment	0	0	3,057	13,069
Total operating expenses	98,943	103,788	309,838	332,829
Operating income	29,495	25,906	77,311	60,548
Other income (expense)
Interest income	79	291	635	970
Interest expense	(19,732)	(20,814)	(61,473)	(64,334)
Interest expense - amortization of deferred financing costs	(577)	(645)	(1,807)	(2,063)
Interest expense - financing obligation	0	(156)	0	(679)
Equity in loss of Real Estate Ventures	(5,723)	(7,254)	(5,387)	(9,323)
Net gain (loss) on disposition of real estate	0	(104)	8,411	114,625
Net gain on sale of undepreciated real estate	953	188	953	188
Net gain on Real Estate Venture transactions	13,758	10,472	28,340	19,529
Loss on early extinguishment of debt	0	0	0	(66,590)
Net income before income taxes	18,253	7,884	46,983	52,871
Income tax benefit	793	0	1,032	0
Net income	19,046	7,884	48,015	52,871
Net income from continuing operations attributable to non-controlling interests - consolidated real estate ventures	(12)	(6)	(25)	(12)
Net income attributable to Brandywine Realty Trust	19,034	7,878	47,990	52,859
Distribution to preferred shareholders	0	(1,725)	(2,032)	(5,175)
Preferred share redemption charge	0	0	(3,181)	0
Nonforfeitable dividends allocated to unvested restricted shareholders	(73)	(79)	(245)	(263)
Net income attributable to Common Shareholders of Brandywine Realty Trust	$ 18,961	$ 6,074	$ 42,532	$ 47,421
Basic income per Common Share	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Diluted income per Common Share	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Basic weighted average shares outstanding	176,913,456	176,606,909	176,795,380	176,491,311
Diluted weighted average shares outstanding	178,314,821	177,844,414	178,079,131	177,524,135
Distributions declared per Common Share	$ 0.16	$ 0.16	$ 0.48	$ 0.47

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net income		$ 19,046	$ 7,884	$ 48,015	$ 52,871
Comprehensive income:
Unrealized gain (loss) on derivative financial instruments		312	2,454	(59)	(10,764)
Reclassification of realized losses on derivative financial instruments to operations, net	[1]	314	286	905	818
Total comprehensive income (loss)		626	2,740	846	(9,946)
Comprehensive income		19,672	10,624	48,861	42,925
Comprehensive income attributable to non-controlling interest		(174)	(81)	(391)	(339)
Comprehensive income attributable to reporting entity		19,498	10,543	48,470	42,586
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Net income		19,046	7,884	48,015	52,871
Comprehensive income:
Unrealized gain (loss) on derivative financial instruments		312	2,454	(59)	(10,764)
Reclassification of realized losses on derivative financial instruments to operations, net	[1]	314	286	905	818
Total comprehensive income (loss)		626	2,740	846	(9,946)
Comprehensive income		19,672	10,624	48,861	42,925
Comprehensive income attributable to non-controlling interest		(12)	(6)	(25)	(12)
Comprehensive income attributable to reporting entity		$ 19,660	$ 10,618	$ 48,836	$ 42,913
[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	Preferred Stock [Member]	Common Stock [Member]	Deferred Compensation, Share-based Payments [Member]	Additional Paid-in Capital [Member]	Common Stock In Grantor Trust [Member]	Cumulative Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Cumulative Distributions [Member]	Noncontrolling Interest [Member]
Beginning Balance at Dec. 31, 2015	$ 1,952,091	$ 40	$ 1,747	$ 11,918	$ 3,252,622	$ (11,918)	$ 499,086	$ (5,192)	$ (1,814,378)	$ 18,166
Beginning Balance, Shares at Dec. 31, 2015		4,000,000	174,688,568	745,686
Net income	52,871						52,446			425
Other comprehensive income (loss)	(9,946)							(9,860)		(86)
Issuance of partnership interest in consolidated real estate venture	73									73
Conversion of LP Units to Common Shares			$ 1		874					(875)
Conversion of LP Units to Common Shares, Shares			55,303
Share-based compensation activity	4,934		$ 4		4,890		40
Share-based compensation activity, Shares			405,200
Share Issuance from/(to) Deferred Compensation Plan	(47)			$ 1,766	(47)	(1,766)
Share Issuance from/(to) Deferred Compensation Plan, Shares			(8,311)	153,771
Adjustment to Non-controlling Interest					(290)					290
Preferred Share distributions	(5,175)								(5,175)
Distributions declared	(83,227)								(82,523)	(704)
Ending Balance at Sep. 30, 2016	1,911,574	$ 40	$ 1,752	$ 13,684	3,258,049	(13,684)	551,572	(15,052)	(1,902,076)	17,289
Ending Balance, Shares at Sep. 30, 2016		4,000,000	175,140,760	899,457
Beginning Balance at Dec. 31, 2016	1,883,437	$ 40	$ 1,752	$ 13,684	3,258,870	(13,684)	539,319	(1,745)	(1,931,892)	17,093
Beginning Balance, Shares at Dec. 31, 2016		4,000,000	175,140,760	899,457
Net income	48,015						47,631			384
Other comprehensive income (loss)	846							839		7
Redemption of Preferred Shares	(96,850)	$ (40)			(96,810)
Redemption of Preferred Shares, Shares		(4,000,000)
Issuance of partnership interest in consolidated real estate venture	85									85
Distributions from consolidated real estate venture	(46)									(46)
Equity issuance costs	(499)				(499)
Bonus share issuance	110				110
Bonus share issuance, Shares			6,752
Share-based compensation activity	5,907		$ 3		5,900		4
Share-based compensation activity, Shares			333,127	39,870
Share Issuance from/(to) Deferred Compensation Plan	(48)			$ 406	(48)	(406)
Share Issuance from/(to) Deferred Compensation Plan, Shares			(1,718)	61,639
Share Choice Plan Issuance, Shares			(1,423)
Adjustment to Non-controlling Interest					(42)					42
Preferred Share distributions	(2,032)								(2,032)
Preferred Share redemption charges	(3,181)								(3,181)
Distributions declared	(85,174)								(84,463)	(711)
Ending Balance at Sep. 30, 2017	$ 1,750,570		$ 1,755	$ 14,090	$ 3,167,481	$ (14,090)	$ 586,954	$ (906)	$ (2,021,568)	$ 16,854
Ending Balance, Shares at Sep. 30, 2017			175,477,498	1,000,966

Consolidated Statements of Ben7

Consolidated Statements of Beneficiaries' Equity (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Distributions declared per Common Share	$ 0.48	$ 0.47
Cumulative Distributions [Member]
Distributions declared per Common Share	0.48	0.47
Noncontrolling Interest [Member]
Distributions declared per Common Share	$ 0.48	$ 0.47

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 48,015	$ 52,871
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	132,584	142,736
Amortization of deferred financing costs	1,807	2,063
Amortization of debt discount/(premium), net	1,069	1,108
Amortization of stock compensation costs	4,321	3,612
Straight-line rent income	(21,002)	(22,049)
Amortization of acquired above (below) market leases, net	(2,280)	(5,090)
Straight-line ground rent expense	66	66
Provision for doubtful accounts	1,622	573
Net gain on real estate venture transactions	(28,340)	(19,529)
Net gain on sale of interests in real estate	(9,364)	(114,813)
Loss on early extinguishment of debt	0	66,590
Provision for impairment	3,057	13,069
Other than temporary impairment	4,844	0
Real Estate Venture loss in excess of distributions	199	9,945
Deferred financing obligation	0	(681)
Income tax benefit	(1,133)	0
Changes in assets and liabilities:
Accounts receivable	(4,445)	4,041
Other assets	(8,927)	(10,332)
Accounts payable and accrued expenses	6,743	7,163
Deferred income, gains and rent	(3,160)	(2,000)
Other liabilities	2,107	318
Net cash provided by operating activities	127,783	129,661
Cash flows from investing activities:
Acquisition of properties	(34,748)	(20,406)
Proceeds from the sale of properties	114,821	758,931
Proceeds from real estate venture sales	59,022	20,551
Issuance of mortgage note receivable	0	(3,365)
Capital expenditures for tenant improvements	(44,902)	(37,991)
Capital expenditures for redevelopments	(21,951)	(10,852)
Capital expenditures for developments	(53,560)	(147,831)
Advances for the purchase of tenant assets, net of repayments	1,148	275
Investment in unconsolidated Real Estate Ventures	(5,243)	(27,174)
Deposits for real estate	605	(746)
Escrowed cash	0	6,993
Cash distribution from unconsolidated Real Estate Ventures in excess of cumulative equity income	14,906	12,565
Leasing costs paid	(12,553)	(12,884)
Net cash provided by investing activities	17,545	538,066
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	86,900
Repayments of mortgage notes payable	(3,681)	(355,947)
Proceeds from credit facility borrowings	264,000	195,000
Repayments of credit facility borrowings	(86,000)	(195,000)
Repayments of unsecured notes	(300,000)	(149,919)
Debt financing costs paid	0	(477)
Redemption of preferred shares	(100,000)	0
Proceeds from the exercise of stock options	1,229	1,286
Shares used for employee taxes upon vesting of share awards	(674)	(879)
Partner contributions to consolidated real estate venture	85	73
Partner distributions from consolidated real estate venture	(46)	0
Distributions paid to shareholders	(88,162)	(85,702)
Distributions to non-controlling interest	(711)	(697)
Net cash used in financing activities	(313,960)	(505,362)
Increase (decrease) in cash and cash equivalents	(168,632)	162,365
Cash and cash equivalents at beginning of year	193,919	56,694
Cash and cash equivalents at end of period	25,287	219,059
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the nine months ended September 30, 2017 and 2016 of $2,975 and $10,023, respectively	58,252	64,046
Cash paid for income taxes	225	0
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	28,391	30,036
Change in investment in real estate ventures as a result of dispositions	(30,584)	(2,023)
Change in investment in real estate ventures related to non-cash disposition of property	0	25,165
Change in real estate ventures as a result of other than temporary impairment	(4,844)	0
Change in operating real estate from deconsolidation of 3141 Fairview Park Drive	0	44,313
Change in investment in real estate ventures from deconsolidation of 3141 Fairview Park Drive	0	(12,642)
Change in mortgage notes payable from deconsolidation of 3141 Fairview Park Drive	0	(20,582)
Change in other liabilities from deconsolidation of 3141 Fairview Park Drive	0	(12,384)
Change in capital expenditures financed through accounts payable at period end	(1,455)	(5,012)
Change in capital expenditures financed through retention payable at period end	83	2,487
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Cash flows from operating activities:
Net income	48,015	52,871
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	132,584	142,736
Amortization of deferred financing costs	1,807	2,063
Amortization of debt discount/(premium), net	1,069	1,108
Amortization of stock compensation costs	4,321	3,612
Straight-line rent income	(21,002)	(22,049)
Amortization of acquired above (below) market leases, net	(2,280)	(5,090)
Straight-line ground rent expense	66	66
Provision for doubtful accounts	1,622	573
Net gain on real estate venture transactions	(28,340)	(19,529)
Net gain on sale of interests in real estate	(9,364)	(114,813)
Loss on early extinguishment of debt	0	66,590
Provision for impairment	3,057	13,069
Other than temporary impairment	4,844	0
Real Estate Venture loss in excess of distributions	199	9,945
Deferred financing obligation	0	(681)
Income tax benefit	(1,133)	0
Changes in assets and liabilities:
Accounts receivable	(4,445)	4,041
Other assets	(8,927)	(10,332)
Accounts payable and accrued expenses	6,743	7,163
Deferred income, gains and rent	(3,160)	(2,000)
Other liabilities	2,107	318
Net cash provided by operating activities	127,783	129,661
Cash flows from investing activities:
Acquisition of properties	(34,748)	(20,406)
Proceeds from the sale of properties	114,821	758,931
Proceeds from real estate venture sales	59,022	20,551
Issuance of mortgage note receivable	0	(3,365)
Capital expenditures for tenant improvements	(44,902)	(37,991)
Capital expenditures for redevelopments	(21,951)	(10,852)
Capital expenditures for developments	(53,560)	(147,831)
Advances for the purchase of tenant assets, net of repayments	1,148	275
Investment in unconsolidated Real Estate Ventures	(5,243)	(27,174)
Deposits for real estate	605	(746)
Escrowed cash	0	6,993
Cash distribution from unconsolidated Real Estate Ventures in excess of cumulative equity income	14,906	12,565
Leasing costs paid	(12,553)	(12,884)
Net cash provided by investing activities	17,545	538,066
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	86,900
Repayments of mortgage notes payable	(3,681)	(355,947)
Proceeds from credit facility borrowings	264,000	195,000
Repayments of credit facility borrowings	(86,000)	(195,000)
Repayments of unsecured notes	(300,000)	(149,919)
Debt financing costs paid	0	(477)
Redemption of preferred shares	(100,000)	0
Proceeds from the exercise of stock options	1,229	1,286
Shares used for employee taxes upon vesting of share awards	(674)	(879)
Partner contributions to consolidated real estate venture	85	73
Partner distributions from consolidated real estate venture	(46)	0
Distributions paid to shareholders	(88,873)	(86,399)
Net cash used in financing activities	(313,960)	(505,362)
Increase (decrease) in cash and cash equivalents	(168,632)	162,365
Cash and cash equivalents at beginning of year	193,919	56,694
Cash and cash equivalents at end of period	25,287	219,059
Supplemental disclosure:
Cash paid for interest, net of capitalized interest during the nine months ended September 30, 2017 and 2016 of $2,975 and $10,023, respectively	58,252	64,046
Cash paid for income taxes	225	0
Supplemental disclosure of non-cash activity:
Dividends and distributions declared but not paid	28,391	30,036
Change in investment in real estate ventures as a result of dispositions	(30,584)	(2,023)
Change in investment in real estate ventures related to non-cash disposition of property	0	25,165
Change in real estate ventures as a result of other than temporary impairment	(4,844)	0
Change in operating real estate from deconsolidation of 3141 Fairview Park Drive	0	44,313
Change in investment in real estate ventures from deconsolidation of 3141 Fairview Park Drive	0	(12,642)
Change in mortgage notes payable from deconsolidation of 3141 Fairview Park Drive	0	(20,582)
Change in other liabilities from deconsolidation of 3141 Fairview Park Drive	0	(12,384)
Change in capital expenditures financed through accounts payable at period end	(1,455)	(5,012)
Change in capital expenditures financed through retention payable at period end	$ 83	$ 2,487

Consolidated Statements of Cas9

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Supplemental disclosure:
Capitalized interest	$ 2,975	$ 10,023
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Supplemental disclosure:
Capitalized interest	$ 2,975	$ 10,023

Consolidated Statements of Part

Consolidated Statements of Partners' Equity - USD ($) $ in Thousands	Total	BRANDYWINE OPERATING PARTNERSHIP, L.P.	General Partner Capital [Member]BRANDYWINE OPERATING PARTNERSHIP, L.P.	Series E-linked Preferred Stock [Member]BRANDYWINE OPERATING PARTNERSHIP, L.P.	Accumulated Other Comprehensive Loss [Member]	Accumulated Other Comprehensive Loss [Member]BRANDYWINE OPERATING PARTNERSHIP, L.P.	Noncontrolling Interest [Member]	Noncontrolling Interest [Member]BRANDYWINE OPERATING PARTNERSHIP, L.P.
Beginning Balance at Dec. 31, 2015		$ 1,929,977	$ 1,836,692	$ 96,850		$ (5,597)		$ 2,032
Beginning Balance, Shares at Dec. 31, 2015			174,688,568	4,000,000
Net income	$ 52,871	52,871	$ 52,859				$ 425	12
Other comprehensive income (loss)	(9,946)	(9,946)			$ (9,860)	(9,946)	(86)
Share Issuance from/(to) Deferred Compensation Plan	(47)	(47)	$ (47)
Share Issuance from/(to) Deferred Compensation Plan, Shares			(8,311)
Issuance of partnership interest in consolidated real estate venture	73	73					73	73
Conversion of LP Units to Common Shares		875	$ 875				(875)
Conversion of LP Units to Common Shares, Shares			55,303
Share-based compensation activity	4,934	4,929	$ 4,929
Share-based compensation activity, Shares			405,200
Adjustment of redeemable partnership units to liquidation value at period end		(1,935)	$ (1,935)
Redemption value of limited partnership units		(875)	(875)
Distribution to preferred shareholders	(5,175)	(5,175)	(5,175)
Preferred Mirror Units redemption charge	0	0
Distributions to general partnership unitholders		(82,524)	(82,524)
Ending Balance at Sep. 30, 2016		1,888,223	$ 1,804,799	$ 96,850		(15,543)		2,117
Ending Balance, Shares at Sep. 30, 2016			175,140,760	4,000,000
Beginning Balance at Dec. 31, 2016		1,859,642	$ 1,762,764	$ 96,850		(2,122)		2,150
Beginning Balance, Shares at Dec. 31, 2016			175,140,760	4,000,000
Net income	48,015	48,015	$ 47,990				384	25
Other comprehensive income (loss)	846	846			$ 839	846	7
Redemption of Preferred Mirror Units		(96,850)		$ (96,850)
Redemption of Preferred Mirror Units, Shares				(4,000,000)
Share Issuance from/(to) Deferred Compensation Plan	(48)	(48)	$ (48)
Share Issuance from/(to) Deferred Compensation Plan, Shares			(1,718)
Issuance of LP Units		(499)	$ (499)
Issuance of partnership interest in consolidated real estate venture	85	86					85	86
Distributions from consolidated real estate venture	(46)	(46)					$ (46)	(46)
Share Choice Plan Issuance, Shares			(1,423)
Bonus share issuance	110	110	$ 110
Bonus share issuance, Shares			6,752
Share-based compensation activity	5,907	5,907	$ 5,907
Share-based compensation activity, Shares			333,127
Adjustment of redeemable partnership units to liquidation value at period end		(2,781)	$ (2,781)
Distribution to preferred shareholders	(2,032)	(2,032)	(2,032)
Preferred Mirror Units redemption charge	$ (3,181)	(3,181)	(3,181)
Distributions to general partnership unitholders		(84,463)	(84,463)
Ending Balance at Sep. 30, 2017		$ 1,724,706	$ 1,723,767			$ (1,276)		$ 2,215
Ending Balance, Shares at Sep. 30, 2017			175,477,498

Consolidated Statements of Pa11

Consolidated Statements of Partners' Equity (Parenthetical) - BRANDYWINE OPERATING PARTNERSHIP, L.P. - $ / shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Distributions to general partnership unitholders (USD per share)	$ 0.48	$ 0.47
General Partner Capital [Member]
Distributions to general partnership unitholders (USD per share)	$ 0.48	$ 0.47

Organization of the Parent Comp

Organization of the Parent Company and The Operating Partnership	9 Months Ended
	Sep. 30, 2017
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 The Parent Company is a self-administered and self-managed real estate investment trust (“REIT”) that provides leasing, property management, development, redevelopment, acquisition and other tenant-related services for a portfolio of office, residential, flexible stay, retail and mixed-use properties. The Parent Company owns its assets and conducts its operations through the Operating Partnership and subsidiaries of the Operating Partnership. The Parent Company is the sole general partner of the Operating Partnership and, as of September 30, 2017, owned a 99.2% 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”. As of September 30, 2017, the Company owned 97 properties that contain an aggregate of approximately 16.4 million net rentable square feet and consist of 82 office properties, four mixed-use properties, one retail property (87 properties, collectively the “Core Properties”), one development property, three redevelopment properties and six properties classified as held for sale (collectively, the “Properties”). In addition, as of September 30, 2017, the Company owned economic interests in 13 unconsolidated real estate ventures (collectively, the “Real Estate Ventures”), seven of which own properties that contain an aggregate of approximately 7.8 million net rentable square feet of office space; four of which own, in aggregate, 5.7 acres of land held for development and two of which own residential towers that contain 345 and 321 apartment units, respectively. As of September 30, 2017, the Company also owned 214 acres of undeveloped land and held options to purchase approximately 60 additional acres of undeveloped land. As of September 30, 2017, the total potential development that these land parcels could support, including the parcels under option, amounted to an estimated 15.7 million square feet. The Properties and the properties owned by the Real Estate Ventures are located in or near Philadelphia, Pennsylvania; Metropolitan Washington, D.C.; Southern New Jersey; Wilmington, Delaware and Austin, Texas. In addition to managing properties owned by the Company, as of September 30, 2017, the Company was managing approximately 10.0 million net rentable square feet of office and industrial properties for third parties and Real Estate Ventures. The Company conducts its third-party real estate management services business primarily through wholly-owned management company subsidiaries. As of September 30, 2017, the management company subsidiaries were managing properties containing an aggregate of approximately 26.4 million net rentable square feet, of which approximately 16.4 million net rentable square feet related to Properties owned by the Company and approximately 10.0 million net rentable square feet related to properties owned by third parties and Real Estate Ventures. Unless otherwise indicated, all references in this Form 10-Q to square feet represent net rentable area.

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
BASIS OF PRESENTATION	2. BASIS OF PRESENTATION Basis of Presentation The consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, all adjustments (consisting solely of normal recurring matters) for a fair statement of the financial position of the Company as of September 30, 2017, the results of its operations for the three- and nine-month periods ended September 30, 2017 and 2016 and its cash flows for the nine-month periods ended September 30, 2017 and 2016 have been included. The results of operations for such interim periods are not necessarily indicative of the results for a full year. These consolidated financial statements should be read in conjunction with the Parent Company’s and the Operating Partnership’s consolidated financial statements and footnotes included in their combined 2016 Annual Report on Form 10-K filed with the SEC on March 1, 2017. The Company's Annual Report on Form 10-K for the year ended December 31, 2016 contains a discussion of our significant accounting policies under Note 2, "Summary of Significant Accounting Policies". Significant Accounting Policies – Revenue Recognition The Company’s flexible stay revenue consists of room revenue, food and beverage revenue, and revenue from other hotel operating departments (such as parking fees and other guest service fees). These revenues are recorded net of any sales and occupancy taxes collected from the hotel guests. All rebates or discounts are recorded as a reduction to revenue, and there are no material contingent obligations with respect to rebates and discounts offered by the hotel. All revenues are recorded on an accrual basis as they are earned. Any cash received prior to a guest’s arrival is recorded as an advance deposit from the guest and recognized as revenue at the time of the guest's occupancy at the hotel property. Out of Period Adjustment The Company recorded $1.2 million of impairment charges during quarter ended December 31, 2016, which should have been recorded in the consolidated financial statements for the three-month period ended March 31, 2017 and the nine-month period ended September 30, 2017. Management concluded that these misstatements were not material to any prior period, nor were they material to the consolidated financial statements as of and for the three- and nine-month periods ended September 30, 2017. Reclassifications During the first quarter of 2017, the Company adopted ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”), which requires the Company to reclassify employer tax payments on account of employee tax withholdings on share-based awards from operating activities to financing activities in the consolidated statement of cash flows. Prior to the issuance of ASU 2016-09, there was no guidance on the classification of cash paid by an employer to the taxing authorities when directly withholding shares for tax withholding purposes. As a result of the adoption, a $0.9 million cash outflow has been reclassified in the September 30, 2016 consolidated statements of cash flows from operating activities to financing activities. There was no other impact from the adoption of this guidance. During the quarter ended December 31, 2016, the Company early adopted ASU 2016-15, “Classification of Certain Cash Receipts and Cash Payments” (“ASU 2016-15”), which clarifies that debt prepayment costs should be presented as financing activities in the statement of cash flows. As a result of the adoption, $53.4 million was reclassified in the consolidated statements of cash flows from the operating activities section to the financing activities section of the consolidated statements of cash flows, within the “Repayment of mortgage notes payable” caption, for the nine-months period ended September 30, 2016. There was no other impact from the adoption of this guidance. Recent Accounting Pronouncements In August 2017, the Financial Accounting Standards Board (the “FASB”) issued ASU No. 2017-12 (“ASU 2017-12”) to simplify the application of hedge accounting guidance and improve the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements. In addition, ASU 2017-12 requires an entity to present the earnings effect of the hedging instrument in the same income statement line item in which the earnings effect of the hedged item is reported. The transition guidance provides companies with the option of early adopting the new standard using a modified retrospective transition method in any interim period after issuance of the update, or alternatively requires adoption for fiscal years beginning after December 15, 2018. This adoption method requires companies to recognize the cumulative effect of initially applying the guidance as an adjustment to accumulated other comprehensive income with a corresponding adjustment to the opening balance of retained earnings as of the beginning of the fiscal year that an entity adopts the update. The Company is in the process of evaluating the impact of this new guidance on its consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09 (“ASU 2017-09”) to provide guidance to clarify when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the changes in terms or conditions. ASU 2017-09 is effective for all entities for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted and application is prospective. The Company is in the process of evaluating the impact of this new guidance on its consolidated financial statements. In February 2017, the FASB issued ASU No. 2017-05 (“ASU 2017-05”) to provide guidance for recognizing gains and losses from the transfer of nonfinancial assets and in-substance nonfinancial assets in contracts with non-customers, unless other specific guidance applies. The standard requires a company to derecognize nonfinancial assets once it transfers control of a distinct nonfinancial asset or distinct in substance nonfinancial asset. Additionally, when a company transfers its controlling interest in a nonfinancial asset, but retains a noncontrolling ownership interest, the company is required to measure any noncontrolling interest it receives or retains at fair value. The guidance requires companies to recognize a full gain or loss on the transaction. As a result of the new guidance, the guidance specific to real estate sales in ASC 360-20 will be eliminated. ASU 2017-05 is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. The effective date of this guidance coincides with revenue recognition guidance. The Company expects to utilize the modified retrospective approach. Under the modified retrospective approach, the Company is required to evaluate incomplete contracts as of December 31, 2017 to determine if the sale recognition of nonfinancial assets under ASU 2017-05 differs from ASC 360-20. The Company has identified three potential sale contracts that may not be considered completed contracts, as defined under ASU 2017-05 by December 31, 2017. Based on our final assessment of these sale contracts, the revenue and remaining gain on sale for each of these property sales will be recognized when the Company fulfills its performance obligations under each contract. Accordingly, the derecognition of nonfinancial assets and revenue recognition patterns are not expected to change under ASU 2017-05 when compared to ASC 360-20. In May 2016, the FASB issued guidance amending the revenue from contracts with customers standard issued in May 2014, which is not yet effective. The amendments are intended to address implementation issues that were raised by stakeholders and discussed by the Joint Transition Resource Group, and provide additional practical expedients on collectability, noncash consideration, presentation of sales tax and contract modifications and completed contracts at transition. In accordance with the FASB election to defer the effective date of the revenue recognition standard by one year, reporting entities may choose to adopt the standard as of its original effective date or for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Calendar year-end reporting entities are therefore required to apply the new revenue guidance beginning in their 2018 interim and annual financial statements. The Company has evaluated the impact of this new guidance and has determined that the impact of the adoption of this guidance is not material to its financial results. In order to evaluate this standard the Company analyzed all of its revenue streams except for rental revenue because rental revenue recognition is not covered by revenue from contracts with customers. The results of the initial assessment are as follows: • • • •

Real Estate Investments

Real Estate Investments	9 Months Ended
	Sep. 30, 2017
Real Estate [Abstract]
REAL ESTATE INVESTMENTS	3. REAL ESTATE INVESTMENTS As of September 30, 2017 and December 31, 2016, the gross carrying value of the properties was as follows (in thousands): September 30, December 31, 2017 2016 Land $ 470,391 $ 469,522 Building and improvements 2,846,869 2,683,087 Tenant improvements 451,807 433,686 Operating properties 3,769,067 3,586,295 Assets held for sale - real estate investments (a) 47,291 73,591 Total $ 3,816,358 $ 3,659,886 (a) Real estate investments related to assets held for sale above represents gross real estate assets and does not include accumulated depreciation, land held for development or other assets on the balance sheet of the property held for sale. See “ Held for Sale ” below in this Note 3. Acquisition On July 28, 2017, the Company acquired an office building containing 58,587 rentable square feet located at 3000 Market Street, in Philadelphia, Pennsylvania, for $32.7 million. The acquisition was the Section 1031 exchange receiver for the sale of Concord Airport Plaza. See property disposition table below. The purchase of 3000 Market Street is an asset acquisition under ASU 2017-01, which the Company early adopted as of January 1, 2017. As such, the Company capitalized $0.7 million of acquisition-related costs and allocated the purchase price, consisting of the contractual sales price of $32.0 million and the acquisition related costs, to the tangible and intangible assets. The Company utilized a number of sources in making estimates of fair value for purposes of allocating the purchase price to tangible and intangibles assets acquired. The purchase price has been allocated as follows (in thousands): July 18, 2017 Building, land and improvements $ 31,728 Intangible assets acquired (a) 2,838 Below market lease liabilities assumed (b) (1,818 ) $ 32,748 (a) Weighted average amortization period of 5.9 years. (b) Weighted average amortization period of 6.0 years. 3000 Market Street contributed approximately $0.3 million of revenue and a nominal amount of net income, included in the Company’s consolidated income statements, for the period from July 28, 2017 through September 30, 2017. Dispositions The Company sold the following twelve office properties, one retail property and one mixed-use property during the nine-month period ended September 30, 2017 (dollars in thousands): Disposition Date Property/Portfolio Name Location Type Number of Properties Rentable Square Feet Sales Price Net Proceeds on Sale Gain/(Loss) on Sale (a) June 27, 2017 Two, Four A, Four B and Five Eves Drive (Evesham Corporate Center) Marlton, NJ Office 4 134,794 $ 9,700 $ 8,650 $ (325 ) (b) June 12, 2017 7000 Midlantic Drive Mount Laurel, NJ Retail 1 10,784 8,200 7,714 1,413 March 30, 2017 200, 210 & 220 Lake Drive East (Woodland Falls) Cherry Hill, NJ Office 3 215,465 19,000 17,771 (249 ) (c) March 15, 2017 Philadelphia Marine Center (Marine Piers) Philadelphia, PA Mixed-use 1 181,900 21,400 11,182 6,498 (d) March 13, 2017 11700, 11710, 11720 & 11740 Beltsville Drive (Calverton) Beltsville, MD Office 3 313,810 9,000 8,354 - (e) February 2, 2017 1200 & 1220 Concord Avenue (Concord Airport Plaza) Concord, CA Office 2 350,256 33,100 32,010 551 (f) Total Dispositions 14 1,207,009 $ 100,400 $ 85,681 $ 7,888 (a) Gain/(Loss) on Sale is net of closing and other transaction related costs. (b) During the first quarter of 2017, the Company recognized a $1.0 million impairment related to these properties. The loss on sale represents closing costs. (c) During the fourth quarter of 2016, the Company recognized a $7.3 million impairment related to these properties. The loss on sale represents closing costs. (d) On March 15, 2017, the Company sold its sublease interest in the Piers at Penn’s Landing (the “Marine Piers”), which includes leasehold improvements containing 181,900 net rentable square feet, and a marina, located in Philadelphia, Pennsylvania for an aggregate sales price of $21.4 million, which will be paid in two installments. On the closing date, the buyer paid $12.0 million in cash. On the second purchase price installment date, the buyer will pay $9.4 million. The second purchase price installment is due on (a) January 31, 2020, in the event that the tenant at the Marine Piers does not exercise its existing option to extend the term of the sublease or (b) January 15, 2024, in the event that the tenant does exercise its current extension option to extend the term of the sublease. In accordance with ASC 360-20, Real Estate Sales (e) During the fourth quarter of 2016, the Company recognized a $3.0 million impairment related to these properties. During the first quarter of 2017, there was a price reduction of $1.7 million under the agreement of sale and an additional impairment of $1.7 million was recognized. (f) During the fourth quarter of 2016, the Company recognized an $11.5 million impairment related to these properties. This sale is designated as a like-kind exchange under Section 1031 of the Internal Revenue Code (“IRC”) and, as such, the proceeds, totaling $32.0 million after closing costs and prorations, were deposited with a Qualified Intermediary, as defined under the IRC. The proceeds received at closing were recorded as “Other assets” in the Company’s consolidated balance sheet. During the third quarter of 2017, the Company acquired 3000 Market Street in Philadelphia, Pennsylvania using the full balance of the Section 1031 proceeds. See “Acquisition” In addition to the amounts in the table above, the Company recorded $0.5 million gain during the first quarter of 2017 from the receipt of additional cash from the disposition of Cira Square during 2016. For further information relating to this sale, see Note 3, “ Real Estate Investments The Company sold the following land parcels during the nine-month period ended September 30, 2017 (dollars in thousands): Disposition Date Property/Portfolio Name Location Number of Parcels Acres Sales Price Net Proceeds on Sale Gain on Sale September 13, 2017 50 E. Swedesford Square Malvern, PA 1 12.0 $ 7,200 $ 7,098 $ 882 July 18, 2017 Bishop's Gate Mount Laurel, NJ 1 49.5 6,000 5,640 71 (a) April 28, 2017 Garza Ranch - Multi-family Austin, TX 1 8.4 11,800 11,560 - (b) February 15, 2017 Gateway Land - Site C Richmond, VA 1 4.8 1,100 1,043 - (c) January 30, 2017 Garza Ranch - Hotel Austin, TX 1 1.7 3,500 3,277 - (b) Total Dispositions 5 76.4 $ 29,600 $ 28,618 $ 953 (a) During the fourth quarter of 2016, the Company recognized an impairment of $3.0 million. During the second quarter of 2017, the Company recognized an additional impairment of $0.3 million, representing closing costs. See “Land Impairment” section below. (b) The Company has a continuing involvement through a completion guaranty, which requires the Company as developer to complete certain infrastructure improvements on behalf of the buyers of the land parcels. The cash received at settlement was recorded as “Deferred income, gains and rent” on the Company’s consolidated balance sheet and the Company will recognize the sale once the infrastructure improvements are complete. See Note 13, Commitments and Contingencies ” for further discussion of the infrastructure improvements. (c) During the fourth quarter of 2016, the Company recognized a nominal impairment related to this land parcel. Held for Sale The following is a summary of properties classified as held for sale but which did not meet the criteria to be classified within discontinued operations at September 30, 2017 (in thousands): Held for Sale Properties Included in Continuing Operations September 30, 2017 630 Allendale Road - Office (a) Newtown Square - Office (b) Total ASSETS HELD FOR SALE Real estate investments: Operating properties $ 19,482 $ 27,809 $ 47,291 Accumulated depreciation (6,985 ) (9,206 ) (16,191 ) Operating real estate investments, net 12,497 18,603 31,100 Construction-in-progress - 25 25 Total assets held for sale, net $ 12,497 $ 18,628 $ 31,125 LIABILITIES HELD FOR SALE Other liabilities $ 35 $ 234 $ 269 Total liabilities held for sale $ 35 $ 234 $ 269 (a) Office property containing 150,000 rentable square feet located in the Pennsylvania Suburbs segment. (b) Five office properties containing 252,802 rentable square feet located in the Pennsylvania Suburbs segment. As the fair value less anticipated costs to sell exceeded the carrying value for each of the properties included in the above table no impairment loss was recorded. The fair value measurements are based on pricing in the purchase and sale agreements for each of the transactions. As the pricing in the purchase and sales agreements are unobservable, the Company determined that the input utilized to determine fair value for these properties falls within Level 3 in accordance with the fair value hierarchy established by Accounting Standards Codification (ASC) Topic 820, “Fair Value Measurements and Disclosures” As of December 31, 2016, the Company classified three office properties in its Metropolitan Washington, D.C. segment, two office properties in its Other segment and a five-acre parcel of land in its Other segment as held for sale. As of December 31, 2016, $40.7 million and $1.0 million was reclassified from ‘Operating real estate investments, net’ and ‘Land held for development’, respectively, to ‘Assets held for sale, net’ on the consolidated balance sheets; an immaterial amount was reclassified from ‘Other liabilities’ to ‘Liabilities related to assets held for sale’. Land Impairment As of September 30, 2017, the Company evaluated the recoverability of the carrying value of its land parcels that triggered assessment. Based on the analysis, no impairment charges were identified during the three-month period ended September 30, 2017. As of June 30, 2017, the Company determined that it would not recover the carrying value, less cost of sale, of one land parcel, consisting of 50 acres known as Bishop’s Gate that was classified as held for sale as of June 30, 2017. Accordingly, the Company recorded an impairment charge of $0.3 million at June 30, 2017, reducing the aggregate carrying value of the land parcel from $5.9 million to its estimated fair value of $5.6 million. The fair value measurement is based on pricing in the purchase and sale agreement for the property. As the pricing in the purchase and sale agreement is unobservable, the Company determined that the input utilized to determine fair value for the property falls within Level 3 in accordance with the fair value hierarchy established by Accounting Standards Codification (ASC) Topic 820, “ Fair Value Measurements and Disclosures Held for Use Impairment As of September 30, 2017, the Company evaluated the recoverability of the carrying value of its properties that triggered assessment. Based on the analysis, no impairment charges were identified during the three-month period ended September 30, 2017. As of March 31, 2017, the Company evaluated the recoverability of the carrying value of its properties that triggered assessment under the undiscounted cash flow model. Based on the Company’s evaluation, it was determined that due to the reduction in the Company’s intended hold period of four properties located in the Other segment, the Company would not recover the carrying values of these properties. Accordingly, the Company recorded impairment charges on these properties of $1.0 million at March 31, 2017, reflected in the results for the nine-month period ended September 30, 2017, reducing the aggregate carrying values of the properties from $10.2 million to their estimated fair value of $9.2 million. The Company measured these impairments based on a discounted cash flow analysis, using a hold period of 10 years and residual capitalization rates and discount rates of 9.00% and 9.25%, respectively. The results were comparable to indicative pricing in the market. The assumptions used to determine fair value under the income approach are Level 3 inputs in accordance with the fair value hierarchy established by Accounting Standards Codification (ASC) Topic 820, “ Fair Value Measurements and Disclosures During the three-month period ended September 30, 2016, there was no provision for impairment recognized. Real Estate Investments The sales of properties, land and the land parcel held for sale do not represent a strategic shift that has a major effect on the Company's operations and financial results. Accordingly, the operating results of these properties remain classified within continuing operations for all periods presented.

Investment in Unconsolidated Re

Investment in Unconsolidated Real Estate Ventures	9 Months Ended
	Sep. 30, 2017
Equity Method Investments And Joint Ventures [Abstract]
INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES	4. INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES As of September 30, 2017, the Company held ownership interests in 13 unconsolidated Real Estate Ventures for an aggregate investment balance of $236.3 million. The Company formed or acquired interests in these Real Estate Ventures with unaffiliated third parties to develop or manage office, residential and/or mixed-use properties or to acquire land in anticipation of possible development of office, residential and/or mixed-use properties. As of September 30, 2017, seven of the real estate ventures owned properties that contain an aggregate of approximately 7.8 million net rentable square feet of office space; four real estate ventures owned 5.7 acres of land held for development; and two real estate ventures owned residential towers that contain 345 and 321 apartment units, respectively. The Company accounts for its unconsolidated interests in the Real Estate Ventures using the equity method. The Company’s unconsolidated interests range from 20% to 70%, subject to specified priority allocations of distributable cash in certain of the Real Estate Ventures. The Company earned management fees from its Real Estate Ventures of $1.7 million and $4.9 million for the three- and nine-month periods ended September 30, 2017, respectively, and $1.7 million and $4.8 million for the three- and nine-month periods ended September 30, 2016, respectively. The Company earned leasing commission income from its Real Estate Ventures of $0.4 million and $3.3 million for the three- and nine-month periods ended September 30, 2017, respectively, and $0.8 million and $1.9 million for the three- and nine-month periods ended September 30, 2016, respectively. The Company has outstanding accounts receivable balances from its Real Estate Ventures of $1.1 million and $1.4 million as of September 30, 2017 and December 31, 2016, respectively. The amounts reflected in the following tables (except for the Company’s share of equity and income) are based on the financial information of the individual Real Estate Ventures. The Company does not record operating losses of a Real Estate Venture in excess of its investment balance unless 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 following is a summary of the financial position of the Real Estate Ventures in which the Company held interests as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Net property $ 1,329,601 $ 1,483,067 Other assets 205,631 231,972 Other liabilities 109,041 129,486 Debt, net 910,842 989,738 Equity 515,349 595,815 Company’s share of equity (Company’s basis) (a) $ 236,313 $ 281,331 (a) This amount includes the effect of the basis difference between the Company's historical cost basis and the basis recorded at the Real Estate Venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from the impairment of investments, purchases of third party interests in existing Real Estate Ventures and upon the transfer of assets that were previously owned by the Company into a Real Estate Venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the Real Estate Venture level. The following is a summary of results of operations of the Real Estate Ventures in which the Company held interests during the three- and nine-month periods ended September 30, 2017 and 2016 (in thousands): Three-month periods ended September 30, Nine-month periods ended September 30, 2017 2016 2017 2016 Revenue $ 56,511 $ 57,710 $ 169,609 $ 157,641 Operating expenses (27,419 ) (27,592 ) (77,757 ) (81,347 ) Provision for impairment - (10,476 ) - (10,476 ) Interest expense, net (11,670 ) (12,102 ) (33,771 ) (32,019 ) Depreciation and amortization (20,684 ) (22,722 ) (61,816 ) (63,125 ) Net loss (a) $ (3,262 ) $ (15,182 ) $ (3,735 ) $ (29,326 ) Equity in loss of Real Estate Ventures (b) $ (5,723 ) $ (7,254 ) $ (5,387 ) $ (9,323 ) (a) The nine-month period ended September (b) The three- and nine-month periods ended September 30, 2017 include a $4.8 million other than temporary impairment charge related to the BDN-AI Venture that was recorded during the three months ended September 30, 2017. Brandywine AI Venture – 7101 Wisconsin Property Sale On December 20, 2011, the Company formed a real estate venture, Brandywine - AI Venture LLC, (the "BDN-AI Venture"), with Current Creek Investments, LLC ("Current Creek"), a wholly-owned subsidiary of Allstate Insurance Company. The Company and Current Creek each own a 50% interest in the BDN-AI Venture. The BDN-AI Venture owned six office properties, which the Company contributed three properties to the BDN-AI Venture upon its formation and three properties that were acquired by the BDN-AI Venture subsequent to its formation. The contributed office properties contain an aggregate of 587,317 net rentable square feet and consist of 3130 and 3141 Fairview Park Drive, both located in Falls Church, Virginia, and 7101 Wisconsin Avenue located in Bethesda, Maryland. On July 10, 2012, the BDN-AI Venture acquired three office properties containing an aggregate 510,202 net rentable square feet and consist of 1010 Wayne Avenue, 1100 Wayne Avenue and 8484 Georgia Avenue located in Silver Spring, Maryland. On September 14, 2017, the BDN-AI Venture completed the sale of 7101 Wisconsin Avenue containing 230,904 rentable square feet located in Bethesda, Maryland, for a gross sales price of $105.7 million. At the time of sale, the property was encumbered by a $37.4 million of first mortgage financing, which was repaid in full resulting in a debt prepayment penalty of $0.8 million. Subsequent to the sales transaction, first mortgage payoff and closing costs, BDN-AI Venture received cash proceeds of $63.6 million. The Company was allocated 50% for its interest and received net cash proceeds of $31.8 million and recognized a $13.8 million gain on the real estate venture’s transaction. Subsequent to the sale transaction, the BDN-AI Venture owned 5 properties consisting of 874,479 rentable square feet and the Company’s equity method investment balance in the BDN-AI Venture was $49.1 million. Brandywine AI Venture – Other Than Temporary Impairment Each quarter, management estimates the fair value of its ownership interest in the Real Estate Ventures, considering the estimated fair value of the real estate assets owned by the Real Estate Ventures and the related indebtedness, as well as the working capital assets and liabilities of the Real Estate Ventures and the terms of the related Real Estate Venture agreements. The Company’s estimates of fair value of the real estate assets incorporate a number of assumptions that are subject to economic and market uncertainties including demand for space, competition for tenants, current market rental rates, changes in market rental rates, operating costs, capitalization rates, holding periods and discount rates. For these assumptions, the Company considered its experience and historical performance in the various markets and data provided by market research organizations. In assessing whether the impairment is other than temporary, the Company considers several factors. The longevity and severity of the impairment are considered as well as the expected time for recovery of value to occur, if ever. As of September 30, 2017, the Company evaluated the recoverability of its investment basis in BDN-AI Venture utilizing a discounted cash flow model. Based on the Company’s evaluation of the fair value of the Company’s investment in the five remaining properties within BDN-AI Venture subsequent to the disposition of 7101 Wisconsin Avenue, it was determined that a continuing situation of weak demand for space and intense competition for tenants was leading to the Company’s share of fair value of the remaining properties to be less than its investment basis in the unconsolidated real estate venture. This continuing and sustained impairment in value, as suggested by the discounted cash flows and the other assessment considerations described above, caused the Company to conclude that the decline in value was other than temporary for its investment in the BDN-AI Venture. During the nine-month period ended September 30, 2017, the Company’s investment basis was $49.1 million, before a $4.8 million impairment charge. Subsequent to the impairment charge, the Company had a net basis of $44.3 million. Determining the current fair value of the Company’s investment is based on a number of factors that are difficult to predict. The market may decline further and future impairment charges may be needed. The Company measured this impairment based on a discounted cash flow analysis, using a hold period of 10 years, a residual capitalization rate of 7.5% and discount rates ranging from 7.8% to 8.5%. The assumptions to determine fair value under the income approach are Level 3 inputs in accordance with the fair value hierarchy established by Accounting Standards Codification (ASC) Topic 820, “ Fair Value Measurements and Disclosures The Parc at Plymouth Meeting Venture On January 31, 2017, the Company sold its 50% interest in TB-BDN Plymouth Apartments, L.P., a 50/50 real estate venture with Toll Brothers, at a gross sales value of $100.5 million, of which the Company was allocated 50% for its interest. The venture developed and operated a 398-unit multi-family complex in Plymouth Meeting, Pennsylvania encumbered by a $54.0 million construction loan. The construction loan was repaid commensurate with the sale of the Company’s 50% interest. As a result, the Company is no longer subject to a $3.2 million payment guarantee on the construction loan. The cash proceeds, after the payment of the Company’s share of the debt and closing costs, were $27.2 million. The carrying amount of the Company’s investment at the time of sale was $12.6 million, resulting in a $14.6 million gain on sale of interest in the real estate venture. Guarantees As of September 30, 2017, the Company’s unconsolidated real estate ventures had aggregate indebtedness to third parties of $915.0 million. These loans are generally mortgage or construction loans, most of which are non-recourse to the Company. As of September 30, 2017, the loans for which there is recourse to the Company consist of the following: ( Investment in Unconsolidated Real Estate Ventures,

Intangible Assets and Liabiliti

Intangible Assets and Liabilities	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS AND LIABILITIES	5. INTANGIBLE ASSETS AND LIABILITIES As of September 30, 2017 and December 31, 2016, the Company’s intangible assets/liabilities were comprised of the following (in thousands): September 30, 2017 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 100,519 $ (45,765 ) $ 54,754 Tenant relationship value 12,831 (10,646 ) 2,185 Above market leases acquired 4,354 (2,476 ) 1,878 Total intangible assets, net $ 117,704 $ (58,887 ) $ 58,817 Acquired lease intangibles, net: Below market leases acquired $ 32,158 $ (15,002 ) $ 17,156 December 31, 2016 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 142,889 $ (75,696 ) $ 67,193 Tenant relationship value 13,074 (10,167 ) 2,907 Above market leases acquired 4,718 (2,340 ) 2,378 Total intangible assets, net $ 160,681 $ (88,203 ) $ 72,478 Acquired lease intangibles, net: Below market leases acquired $ 37,579 $ (19,460 ) $ 18,119 As of September 30, 2017, the Company’s annual amortization for its intangible assets/liabilities, assuming no prospective early lease terminations, are as follows (dollars in thousands): Assets Liabilities 2017 (three months remaining) $ 3,443 $ 677 2018 12,257 2,512 2019 10,984 2,198 2020 8,904 1,650 2021 6,366 1,062 Thereafter 16,863 9,057 Total $ 58,817 $ 17,156

Debt Obligations

Debt Obligations	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
DEBT OBLIGATIONS	6. DEBT OBLIGATIONS The following table sets forth information regarding the Company’s consolidated debt obligations outstanding at September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Effective Interest Rate Maturity Date MORTGAGE DEBT: Two Logan Square $ 84,839 $ 86,012 3.98% May 2020 One Commerce Square 124,518 127,026 3.64% (a) Apr 2023 Two Commerce Square 112,000 112,000 4.51% (b) Apr 2023 Principal balance outstanding 321,357 325,038 Plus: fair market value premium (discount), net (2,434 ) (2,761 ) Less: deferred financing costs (606 ) (728 ) Mortgage indebtedness $ 318,317 $ 321,549 UNSECURED DEBT $600.0M Revolving Credit Facility $ 178,000 $ - LIBOR + 1.20% May 2019 Seven-Year Term Loan - Swapped to fixed 250,000 250,000 3.72% Oct 2022 $300.0M 5.70% Guaranteed Notes due 2017 (c) - 300,000 5.68% May 2017 $325.0M 4.95% Guaranteed Notes due 2018 325,000 325,000 5.13% Apr 2018 $250.0M 3.95% Guaranteed Notes due 2023 250,000 250,000 4.02% Feb 2023 $250.0M 4.10% Guaranteed Notes due 2024 250,000 250,000 4.33% Oct 2024 $250.0M 4.55% Guaranteed Notes due 2029 250,000 250,000 4.60% Oct 2029 Indenture IA (Preferred Trust I) - Swapped to fixed 27,062 27,062 2.75% Mar 2035 Indenture IB (Preferred Trust I) - Swapped to fixed 25,774 25,774 3.30% Apr 2035 Indenture II (Preferred Trust II) - Swapped to fixed 25,774 25,774 3.09% Jul 2035 Principal balance outstanding 1,581,610 1,703,610 Plus: original issue premium (discount), net (3,937 ) (4,678 ) Less: deferred financing costs (6,350 ) (7,369 ) Total unsecured indebtedness $ 1,571,323 $ 1,691,563 Total Debt Obligations $ 1,889,640 $ 2,013,112 (a) This loan was assumed upon acquisition of the related properties on December 19, 2013. On December 29, 2015, the Company refinanced the debt increasing the principal balance to $130.0 million and extended the scheduled maturity date from January 6, 2016 to April 5, 2023. The effective interest rate as of December 31, 2015 was 3.64%. A default under this loan will also constitute a default under the loan secured by Two Commerce Square. This loan is also secured by a lien on Two Commerce Square. (b) This loan was assumed upon acquisition of the related property on December 19, 2013. The interest rate reflects the market rate at the time of acquisition. A default under this loan will also constitute a default under the loan secured by One Commerce Square. This loan is also secured by a lien on One Commerce Square. (c) On May 1, 2017, the entire principal balance of the unsecured 5.70% Guaranteed Notes was repaid upon maturity. Available cash balances and the Credit Facility (as defined below) were used to fund the repayment of the unsecured notes. As of September 30, 2017 and December 31, 2016, The Company utilizes its four-year unsecured revolving credit facility (the “Credit Facility”) borrowings for general business purposes, including acquisition, development and redevelopment properties and the repayment of other debt. The Credit Facility provides for borrowings of up to $600.0 million and the per annum variable interest rate on the outstanding balances is LIBOR plus 1.20%. The interest rate and facility fee are subject to adjustment upon a change in the Company’s unsecured debt ratings. As of September 30, 2017, the Company had million of borrowings and $13.5 million in letters of credit outstanding, leaving $408.5 million of unused availability under the Credit Facility. During the nine months ended September 30, 2017, the weighted-average interest rate on Credit Facility borrowings was 2.34%. As of September 30, 2017, the effective interest rate on Credit Facility borrowings was 2.43%. As of and during the nine-month period ended September 30, 2016, the Company had no borrowings under the Credit Facility. The Parent Company unconditionally guarantees the unsecured debt obligations of the Operating Partnership (or is a co-borrower with the Operating Partnership) but does not by itself incur unsecured indebtedness. The Parent Company has no material assets other than its investment in the Operating Partnership. The Company was in compliance with all financial covenants as of September 30, 2017. Management continuously monitors the Company’s compliance with and anticipated compliance with the covenants. Certain of the covenants restrict the Company’s ability to obtain alternative sources of capital. While the Company currently believes it will remain in compliance with its covenants, in the event that the economy deteriorates in the future, the Company may not be able to remain in compliance with such covenants, in which case a default would result absent a lender waiver. As of September 30, 2017, the Company’s aggregate scheduled principal payments of debt obligations, excluding amortization of discounts and premiums, are as follows (in thousands): 2017 (three months remaining) $ 1,250 2018 331,601 2019 185,360 2020 86,978 2021 6,099 Thereafter 1,291,679 Total principal payments 1,902,967 Net unamortized premiums/(discounts) (6,371 ) Net deferred financing costs (6,956 ) Outstanding indebtedness $ 1,889,640

Fair Value of Financial Instrum

Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	7. FAIR VALUE OF FINANCIAL INSTRUMENTS Financial assets and liabilities recorded on the consolidated balance sheets are categorized based on the inputs to the valuation techniques as follows: • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access; • Level 2 inputs are inputs, other than quoted prices included in Level 1, which are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals; and • Level 3 inputs are unobservable inputs for the asset or liability, which is typically based on an entity’s own assumptions, as there is little, if any, related market activity or information. The Company determined the fair values disclosed below using available market information and discounted cash flow analyses as of September 30, 2017 and December 31, 2016, respectively. The discount rate used in calculating fair value is the sum of the current risk free rate and the risk premium on the date of measurement of the instruments or obligations. Considerable judgment is necessary to interpret market data and to develop the related estimates of fair value. Accordingly, the estimates presented are not necessarily indicative of the amounts that the Company could realize upon disposition. The use of different estimates and valuation methodologies may have a material effect on the fair value amounts shown. The Company believes that the carrying amounts reflected in the consolidated balance sheets at September 30, 2017 and December 31, 2016 approximate the fair values for cash and cash equivalents, accounts receivable, other assets (except for the note receivable disclosed below), accounts payable and accrued expenses. The following are financial instruments for which the Company’s estimates of fair value differ from the carrying amounts (in thousands): September 30, 2017 December 31, 2016 Carrying Amount (a) Fair Value Carrying Amount (a) Fair Value Unsecured notes payable $ 1,066,366 $ 1,087,263 $ 1,364,854 $ 1,372,758 Variable rate debt $ 504,957 $ 486,653 $ 326,709 $ 307,510 Mortgage notes payable $ 318,317 $ 305,657 $ 321,549 $ 328,853 Note receivable (b) $ 3,384 $ 3,655 $ 3,380 $ 3,717 (a) In April 2015, the FASB issued guidance requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct reduction from the carrying amount of the corresponding debt liability, consistent with debt discounts. As a result, the carrying amounts presented in the table above are net of deferred financing costs of $4.7 million and $5.5 million for unsecured notes payable, $1.7 million and $1.9 million for variable rate debt and $0.6 million and $0.7 million for mortgage notes payable as of September 30, 2017 and December 31, 2016, respectively. (b) The inputs to originate the note receivable are unobservable and, as a result, are categorized as Level 3 . The Company determined fair value by calculating the present value of the cash payments to be received through the maturity date of the loan. See Note 2, “Summary of Significant Accounting Policies,” to the Company’s 2016 Annual Report on Form 10-K for the year ended December 31, 2016 for further information regarding the note origination. The inputs utilized to determine the fair value of the Company’s unsecured notes payable are categorized as Level 2. This is because the Company valued these instruments using quoted market prices as of September 30, 2017 and December 31, 2016. For the fair value of the Company’s unsecured notes, the Company uses a discount rate based on the indicative new issue pricing provided by lenders. The inputs utilized to determine the fair value of the Company’s mortgage notes payable and variable rate debt are categorized as Level 3. The fair value of the variable rate debt was estimated using a discounted cash flow analysis valuation on the borrowing rates currently available to the Company for loans with similar terms and maturities, as applicable. The fair value of the mortgage debt was determined by discounting the future contractual interest and principal payments by a blended market rate for loans with similar terms, maturities and loan-to-value. These inputs have been categorized as Level 3 because the Company considers the rates used in the valuation techniques to be unobservable inputs. For the Company’s mortgage loans, the Company uses an estimate based discounted cash flow analyses and its knowledge of the mortgage market. The weighted average discount rate for the combined variable rate debt and mortgage loans used to calculate fair value as of September 30, 2017 and December 31, 2016 was 4.143% and 4.353%, respectively. An increase in the discount rate used in the discounted cash flow model would result in a decrease to the fair value of the Company’s long-term debt. Conversely, a decrease in the discount rate used in the discounted cash flow model would result in an increase to the fair value of the Company’s long-term debt. Disclosure about the fair value of financial instruments is based upon pertinent information available to management as of September 30, 2017 and December 31, 2016. Although management is not aware of any factors that would significantly affect the fair value amounts, such amounts have not been comprehensively revalued for purposes of these financial statements since September 30, 2017, and current estimates of fair value may differ from the amounts presented herein.

Limited Partners' Non-Controlli

Limited Partners' Non-Controlling Interests in the Parent Company	9 Months Ended
	Sep. 30, 2017
Noncontrolling Interest [Abstract]
LIMITED PARTNERS' NON-CONTROLLING INTERESTS IN THE PARENT COMPANY	8. LIMITED PARTNERS' NON-CONTROLLING INTERESTS IN THE PARENT COMPANY Non-controlling 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. Operating Partnership The aggregate book value of the non-controlling interests associated with the redeemable common limited partnership interests in the accompanying consolidated balance sheet of the Parent Company was $14.6 million and $14.9 million as of September 30, 2017 and December 31, 2016, respectively. Under the applicable accounting guidance, the redemption value of limited partnership units are carried at, on a limited partner basis, the greater of historical cost adjusted for the allocation of income and distributions or fair value. The Parent Company believes that the aggregate settlement value of these interests based on the number of units outstanding and the closing price of the common shares on the balance sheet dates as of September 30, 2017 and December 31, 2016 was approximately $25.9 million and $24.4 million, respectively.

Fair Value of Derivative Financ

Fair Value of Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
FAIR VALUE OF DERIVATIVE FINANCIAL INSTRUMENTS	9. FAIR VALUE OF DERIVATIVE FINANCIAL INSTRUMENTS The following table summarizes the terms and fair values of the Company’s derivative financial instruments as of September 30, 2017 and December 31, 2016. 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 and included in other assets and other liabilities on the Company’s consolidated balance sheets). Hedge Product Hedge Type Designation Notional Amount Strike Trade Date Maturity Date Fair value 9/30/2017 12/31/2016 9/30/2017 12/31/2016 (Liabilities)/Assets Swap Interest Rate Cash Flow (a) $ 250,000 $ 250,000 3.718 % October 8, 2015 October 8, 2022 $ (3,185 ) $ 3,733 Swap Interest Rate Cash Flow (a) 25,774 25,774 3.300 % December 22, 2011 January 30, 2021 (209 ) (300 ) Swap Interest Rate Cash Flow (a) 25,774 25,774 3.090 % January 6, 2012 October 30, 2019 (88 ) (214 ) Swap Interest Rate Cash Flow (a) 27,062 27,062 2.750 % December 21, 2011 September 30, 2017 - (83 ) $ 328,610 $ 328,610 (a) Hedging unsecured variable rate debt. The Company measures its derivative instruments at fair value and records them gross in the consolidated balance sheet in other assets or other liabilities. Additionally, the Company recorded its share of the fair value of derivative financial instruments held by its unconsolidated real estate ventures, as of September 30, 2017. 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 its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy.

Beneficiaries Equity of the Par

Beneficiaries Equity of the Parent Company	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
BENEFICIARIES' EQUITY OF THE PARENT COMPANY	10. BENEFICIARIES’ EQUITY OF THE PARENT COMPANY Earnings per Share (EPS) The following tables detail the number of shares and net income used to calculate basic and diluted earnings per share (in thousands, except share and per share amounts; results may not add due to rounding): Three-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 19,046 $ 19,046 $ 7,884 $ 7,884 Net income from continuing operations attributable to non-controlling interests (170 ) (170 ) (58 ) (58 ) Nonforfeitable dividends allocated to unvested restricted shareholders (73 ) (73 ) (79 ) (79 ) Preferred share dividends - - (1,725 ) (1,725 ) Net income attributable to common shareholders $ 18,803 $ 18,803 $ 6,022 $ 6,022 Denominator Weighted-average shares outstanding 175,433,657 175,433,657 175,127,110 175,127,110 Contingent securities/Share based compensation - 1,401,365 - 1,237,505 Weighted-average shares outstanding 175,433,657 176,835,022 175,127,110 176,364,615 Earnings per Common Share: Net income attributable to common shareholders $ 0.11 $ 0.11 $ 0.03 $ 0.03 Nine-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 48,015 $ 48,015 $ 52,871 $ 52,871 Net income from continuing operations attributable to non-controlling interests (384 ) (384 ) (425 ) (425 ) Nonforfeitable dividends allocated to unvested restricted shareholders (245 ) (245 ) (263 ) (263 ) Preferred share dividends (2,032 ) (2,032 ) (5,175 ) (5,175 ) Preferred share redemption charge (3,181 ) (3,181 ) - - Net income attributable to common shareholders $ 42,173 $ 42,173 $ 47,008 $ 47,008 Denominator Weighted-average shares outstanding 175,315,581 175,315,581 174,976,998 174,976,998 Contingent securities/Share based compensation - 1,283,751 - 1,032,824 Weighted-average shares outstanding 175,315,581 176,599,332 174,976,998 176,009,822 Earnings per Common Share: Net income attributable to common shareholders $ 0.24 $ 0.24 $ 0.27 $ 0.27 Redeemable common limited partnership units totaling 1,479,799 at both September 30, 2017 and September 30, 2016, were excluded from the diluted earnings per share computations because they are not dilutive. Unvested restricted shares are considered participating securities which require the use of the two-class method for the computation of basic and diluted earnings per share. For the three- and nine-month periods ended September 30, 2017 and 2016, 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 September 12, 2017, the Parent Company declared a distribution of $0.16 per common share, totaling $28.4 million, which was paid on October 18, 2017 to shareholders of record as of October 4, 2017. On April 11, 2017, the Parent Company redeemed all of its outstanding 4,000,000 Series E Preferred Shares at an aggregate redemption price of $25.51 per share, which includes $2.0 million of dividends accrued through the redemption date. The redemption was funded with existing cash balances on hand. Also on April 11, 2017, the Parent Company recognized a $3.2 million charge related to the underwriting discount and related expenses incurred at issuance of the Series E Preferred Shares on April 11, 2012. This charge is included in the earnings per share calculations above, as well as within the Parent Company’s consolidated income statements as a reduction in net income to arrive at net income attributable to common shareholders under the caption “Preferred share redemption charge.” There were no comparable charges for the prior year.

Partners Equity of The Operatin

Partners Equity of The Operating Partnership	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
PARTNERS' EQUITY OF THE OPERATING PARTNERSHIP	11. PARTNERS’ EQUITY OF THE OPERATING PARTNERSHIP Earnings per Common Partnership Unit The following tables detail the number of units and net income used to calculate basic and diluted earnings per common partnership unit (in thousands, except unit and per unit amounts; results may not add due to rounding): Three-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 19,046 $ 19,046 $ 7,884 $ 7,884 Nonforfeitable dividends allocated to unvested restricted unitholders (73 ) (73 ) (79 ) (79 ) Preferred unit dividends - - (1,725 ) (1,725 ) Net income attributable to non-controlling interests (12 ) (12 ) (6 ) (6 ) Net income attributable to common unitholders $ 18,961 $ 18,961 $ 6,074 $ 6,074 Denominator Weighted-average units outstanding 176,913,456 176,913,456 176,606,909 176,606,909 Contingent securities/Share based compensation - 1,401,365 - 1,237,505 Total weighted-average units outstanding 176,913,456 178,314,821 176,606,909 177,844,414 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.11 $ 0.11 $ 0.03 $ 0.03 Nine-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 48,015 $ 48,015 $ 52,871 $ 52,871 Nonforfeitable dividends allocated to unvested restricted unitholders (245 ) (245 ) (263 ) (263 ) Preferred unit dividends (2,032 ) (2,032 ) (5,175 ) (5,175 ) Preferred unit redemption charge (3,181 ) (3,181 ) - - Net income attributable to non-controlling interests (26 ) (26 ) (12 ) (12 ) Net income attributable to common unitholders $ 42,531 $ 42,531 $ 47,421 $ 47,421 Denominator Weighted-average units outstanding 176,795,380 176,795,380 176,491,311 176,491,311 Contingent securities/Share based compensation - 1,283,751 - 1,032,824 Total weighted-average units outstanding 176,795,380 178,079,131 176,491,311 177,524,135 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.24 $ 0.24 $ 0.27 $ 0.27 Unvested restricted units are considered participating securities which require the use of the two-class method for the computation of basic and diluted earnings per share. For the three- and nine-month periods ended September 30, 2017 and 2016, earnings representing nonforfeitable dividends as noted in the table above were allocated to the unvested restricted units issued to the Parent Company in connection with awards 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 On September 12, 2017, the Operating Partnership declared a distribution of $0.16 per common partnership unit, totaling $28.4 million, which was paid on October 18, 2017 to unitholders of record as of October 4, 2017. On April 11, 2017, the Operating Partnership redeemed all of its outstanding 4,000,000 Series E-Linked Preferred Mirror Units at an aggregate redemption price of $25.51 per unit, which includes $2.0 million of dividends accrued through the redemption date. The redemption of preferred units was funded with existing cash balances on hand. Also on April 11, 2017, the Operating Partnership recognized a $3.2 million charge related to the underwriting discount and related expenses incurred at issuance of the Series E-Linked Preferred Mirror Units on April 11, 2012. This charge is included in the earnings per share calculations above, as well as within the Operating Partnership’s consolidated income statements as a reduction in net income to arrive at net income attributable to common partnership unitholders under the caption “Preferred unit redemption charge.” There were no comparable charges for the prior year.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
SEGMENT INFORMATION	12. SEGMENT INFORMATION As of September 30, 2017, the Company owns and manages properties within five segments: (1) Philadelphia Central Business District (CBD), (2) Pennsylvania Suburbs, (3) Metropolitan Washington, D.C., (4) Austin, Texas and (5) Other. The Philadelphia CBD segment includes properties located in the City of Philadelphia in Pennsylvania. The Pennsylvania Suburbs segment includes properties in Chester, Delaware, and Montgomery counties in the Philadelphia suburbs. The Metropolitan Washington, D.C. segment includes properties in the District of Columbia, Northern Virginia and southern Maryland. The Austin, Texas segment includes properties in the City of Austin, Texas. The Other segment includes properties located in Camden County in New Jersey and properties in New Castle County in Delaware. On February 2, 2017, the Company sold its last two remaining properties located in California, which were previously included in the Other segment. See Note 3, “Real Estate Investments,” The following tables provide selected asset information and results of operations of the Company's reportable segments (in thousands): Real estate investments, at cost: September 30, 2017 December 31, 2016 Philadelphia CBD $ 1,591,828 $ 1,320,974 Pennsylvania Suburbs (a) 966,128 1,005,446 Metropolitan Washington, D.C. 976,286 975,987 Austin, Texas 146,859 146,794 Other 87,966 137,094 $ 3,769,067 $ 3,586,295 Assets held for sale (b) 47,291 73,591 Operating properties $ 3,816,358 $ 3,659,886 Corporate Construction-in-progress $ 127,141 $ 297,462 Land held for development $ 120,696 $ 150,970 (a) As of September 30, 2017, the Company categorized (b) Real estate investments related to assets held for sale above represents gross real estate assets and does not include accumulated “Real Estate Investments,” None of the above aforementioned sales or properties classified as held for sale are considered significant dispositions under the accounting guidance for discontinued operations. Net operating income (in thousands): Three-month periods ended September 30, 2017 2016 Total revenue Operating expenses (a) Net operating income (loss) Total revenue Operating expenses (a) Net operating income Philadelphia CBD $ 56,452 $ (22,010 ) $ 34,442 $ 50,744 $ (19,071 ) $ 31,673 Pennsylvania Suburbs 34,861 (11,846 ) 23,015 35,763 (11,247 ) 24,516 Metropolitan Washington, D.C. 23,079 (8,500 ) 14,579 24,251 (9,900 ) 14,351 Austin, Texas 7,886 (3,929 ) 3,957 8,726 (3,523 ) 5,203 Other 3,752 (2,647 ) 1,105 8,526 (4,837 ) 3,689 Corporate 2,408 (1,769 ) 639 1,684 (2,739 ) (1,055 ) Operating properties $ 128,438 $ (50,701 ) $ 77,737 $ 129,694 $ (51,317 ) $ 78,377 Nine-month periods ended September 30, 2017 2016 Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income Philadelphia CBD $ 165,352 $ (64,311 ) $ 101,041 $ 148,496 $ (58,102 ) $ 90,394 Pennsylvania Suburbs 105,673 (35,670 ) 70,003 107,971 (36,982 ) 70,989 Metropolitan Washington, D.C. 69,190 (26,347 ) 42,843 76,881 (29,567 ) 47,314 Austin, Texas 25,772 (11,634 ) 14,138 25,123 (9,689 ) 15,434 Other 14,274 (9,083 ) 5,191 30,328 (17,513 ) 12,815 Corporate 6,888 (5,355 ) 1,533 4,578 (4,460 ) 118 Operating properties $ 387,149 $ (152,400 ) $ 234,749 $ 393,377 $ (156,313 ) $ 237,064 (a) Includes property operating expense, real estate taxes and third party management expense. Unconsolidated real estate ventures (in thousands): Investment in real estate ventures, at equity Equity in income (loss) of real estate ventures As of Three-month periods ended September 30, Nine-month periods ended September 30, September 30, 2017 December 31, 2016 2017 2016 2017 2016 Philadelphia CBD $ 42,298 $ 48,691 $ 134 $ (453 ) $ 113 $ (473 ) Pennsylvania Suburbs 3,320 15,421 24 (170 ) 448 410 Metropolitan Washington, D.C. (a) 119,550 141,786 (5,264 ) (5,287 ) (4,872 ) (6,068 ) Austin, Texas 52,940 52,886 (15 ) (561 ) 1,266 (1,299 ) MAP Venture (b) 16,283 20,893 (706 ) (1,010 ) (2,610 ) (2,608 ) Other 1,922 1,654 104 227 268 715 Total $ 236,313 $ 281,331 $ (5,723 ) $ (7,254 ) $ (5,387 ) $ (9,323 ) (a) The three- and nine-month periods ended September 30, 2017 include a $4.8 million other than temporary impairment charge related to the BDN - AI Venture that was recorded during the three months ended September 30, 2017. (b) The MAP Venture represents a joint venture formed between the Company and MAP Ground Lease Holdings LLC, an affiliate of Och-Ziff Capital Management Group, LLC, on February 4, 2016. The MAP Venture’s business operations, including properties in Richmond, Virginia; Metropolitan Washington, D.C.; New Jersey/Delaware and Pennsylvania Suburbs, are centrally managed with the results reported to management of the Company on a consolidated basis. As a result, the investment in the MAP Venture is separately presented. All other unconsolidated real estate ventures are managed consistently with the Company’s regional segments. Net operating income (“NOI”) is a non-GAAP financial measure defined 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, management fees and bad debt expense. 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. All companies may not calculate NOI in the same manner. NOI is the measure that is used by the Company to evaluate the operating performance of its real estate assets by segment. The Company believes NOI provides useful information to investors regarding the financial condition and results of operations because it reflects only those income and expense items that are incurred at the property level. While NOI is a relevant and widely used measure of operating performance of real estate investment trusts, it does not represent cash flow from operations or net income as defined by GAAP and should not be considered as an alternative to those measures in evaluating our liquidity or operating performance. NOI does not reflect interest expenses, real estate impairment losses, depreciation and amortization costs, capital expenditures and leasing costs. The Company believes that net income (loss), as defined by GAAP, is the most appropriate earnings measure. The following is a reconciliation of consolidated net income, as defined by GAAP, to consolidated NOI, (in thousands): Three-month periods ended September 30, Nine-month periods ended September 30, 2017 2016 2017 2016 Net income $ 19,046 $ 7,884 $ 48,015 $ 52,871 Plus: Interest expense 19,732 20,814 61,473 64,334 Interest expense - amortization of deferred financing costs 577 645 1,807 2,063 Interest expense - financing obligation - 156 - 679 Depreciation and amortization 42,429 46,956 132,584 142,736 General and administrative expenses 5,813 5,515 21,797 20,711 Equity in loss of Real Estate Ventures 5,723 7,254 5,387 9,323 Provision for impairment - - 3,057 13,069 Loss on early extinguishment of debt - - - 66,590 Less: Interest income 79 291 635 970 Income tax benefit 793 - 1,032 - Net gain (loss) on disposition of real estate - (104 ) 8,411 114,625 Net gain on sale of undepreciated real estate 953 188 953 188 Net gain on Real Estate Venture transactions 13,758 10,472 28,340 19,529 Consolidated net operating income $ 77,737 $ 78,377 $ 234,749 $ 237,064

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	13. COMMITMENTS AND CONTINGENCIES Legal Proceedings The Company is involved from time to time in litigation on various matters, including disputes with tenants, vendors and disputes arising out of agreements to purchase or sell properties. Given the nature of the Company’s business activities, these lawsuits are considered routine to the conduct of its business. The result of any particular lawsuit cannot be predicted, because of the very nature of litigation, the litigation process and its adversarial nature, and the jury system. The Company will establish reserves for specific legal proceedings when it determines that the likelihood of an unfavorable outcome is probable and when the amount of loss is reasonably estimable. The Company does not expect that the liabilities, if any, that may ultimately result from such legal actions will have a material adverse effect on the consolidated financial position, results of operations or cash flows of the Company. Letters-of-Credit Under certain mortgages, including mortgages held by Real Estate Ventures, the Company may be required to fund required leasing and capital reserve accounts for the benefit of the mortgage lenders with a letter-of-credit. As of September 30, 2017, there is an associated $10.0 million letter of credit for a mortgage lender. Certain of the tenant rents at properties that secure these mortgage loans are deposited into the loan servicer’s depository accounts, which are used to fund debt service, operating expenses, capital expenditures and the escrow and reserve accounts, as necessary. Any excess cash is included in cash and cash equivalents. Environmental As an owner of real estate, the Company is subject to various environmental laws of federal, state, and local governments. The Company’s compliance with existing laws has not had a material adverse effect on its financial condition and results of operations, and the Company does not believe it will have a material adverse effect in the future. However, the Company cannot predict the impact of unforeseen environmental contingencies or new or changed laws or regulations on its current Properties or on properties that the Company may acquire. Ground Rent Future minimum rental payments by the Company under the terms of all non-cancelable ground leases of land on which properties in the Company’s consolidated portfolio are situated are expensed on a straight-line basis regardless of when payments are due. The Company’s ground leases have remaining lease terms ranging from 12 to 72 years. Minimum future rental payments on non-cancelable leases at September 30, 2017 are as follows (in thousands): Year Minimum Rent 2017 (three months remaining) $ 303 2018 1,211 2019 1,211 2020 1,211 2021 1,211 Thereafter 57,527 Total $ 62,674 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 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. Reference is made in our Annual Report on Form 10-K for the year ended December 31, 2016 for further detail regarding commitments and contingencies. Put Agreement On May 4, 2015, the Company entered into a put agreement in the ordinary course of business that grants an unaffiliated third party the unilateral option to require the Company to purchase a property, at a predetermined price, until May 4, 2018. In addition to the $35.0 million purchase price, the Company would be responsible for transaction and closing costs. There can be no assurance that the counterparty will exercise the option. Fair Value of Contingent Consideration On April 2, 2015, the Company purchased 618 Market Street in Philadelphia, Pennsylvania. The allocated purchase price included contingent consideration of $2.0 million payable to the seller upon commencement of development. The liability was initially recorded at fair value of $1.6 million and will accrete through interest expense to $2.0 million over the expected period until development is commenced. The fair value of this contingent consideration was determined using a probability weighted discounted cash flow model. The significant inputs to the discounted cash flow model were the discount rate and weighted probability scenarios. As the inputs are unobservable, the Company determined the inputs used to value this liability fall within Level 3 for fair value reporting. As of September 30, 2017, the liability had accreted to $1.8 million. As there were no significant changes to the inputs, the liability remains within Level 3 for fair value reporting. Debt Guarantees As of September 30, 2017, the Company’s unconsolidated real estate ventures had aggregate indebtedness to third parties of $915.0 million. These loans are generally mortgage or construction loans, most of which are non-recourse to the Company. In addition, in certain instances, the Company provides non-recourse carve-out guarantees on these non-recourse loans. As of September 30, 2017, the loans for which there is recourse to the Company consists of the following: (i) a $55.4 million payment guaranty on the term loan for evo at Cira Centre South; (ii) Investment in Unconsolidated Real Estate Ventures," Other Commitments or Contingencies On July 1, 2016, the Company closed on the acquisition of 34.6 acres of land located in Austin, Texas known as the Garza Ranch. As of September 30, 2017, the Company sold two parcels containing 8.4 acres and 1.7 acres (of the 34.6 acres) to two unaffiliated third parties. In connection with the agreements of sale, the Company entered into a development agreement and related completion guarantee to construct certain infrastructure improvements to the land on behalf of each buyer, estimated to cost $13.2 million. Total estimated costs related to the improvements are included in the sale price of each land parcel. Recognition of the sale of the land parcels is deferred until the improvements are completed. As of September 30, 2017, the costs incurred to complete the infrastructure improvements are not in excess of the fixed sale price included in each sale contract. Accordingly, there are no indicators of impairment. On December 3, 2015, the Company entered into an agreement as development manager to construct Subaru of America’s (“Subaru”) corporate headquarters (the “Subaru Headquarters Development”), an office property containing five floors and approximately 250,000 square feet, on land owned by Subaru and located in Camden, New Jersey. In addition to development fees, the agreement provides the Company with the ability to earn additional profit if total project costs are less than the not-to-exceed (“NTE”) amount. As of September 30, 2017, the Company has recognized $2.1 million of residual profit income related to the Subaru Headquarters Development. For the three- and nine-month periods ended September 30, 2017, the Company earned $0.8 million and $1.6 million, respectively. The NTE amount, currently at $79.4 million, may be adjusted by change orders agreed upon by both Subaru and the Company. If construction costs exceed the NTE amount, the Company is obligated to pay the excess and the residual profit recognized will be reversed. As of September 30, 2017, $57.2 million of the project costs had been funded, and the Company does not expect to incur costs in excess of the NTE amount. The Company expects the development to be substantially complete during the fourth quarter of 2017. Also on December 3, 2015, the Company entered into an agreement to construct an 83,000 square foot build-to-suit service center (the “Subaru NSTC Development”) on land parcels owned by the Company for Subaru as the single tenant. On such date, Subaru entered into an 18-year lease for the service center. The lease contains a purchase option, which allows Subaru to purchase the property at commencement of the lease, or five years subsequent to inception, at depreciated cost. The Company currently expects to deliver the building to Subaru during the third quarter of 2018. At September 30, 2017, $12.4 million of the estimated project costs, totaling $44.3 million, had been funded, and is recorded in Other assets. 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.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2017
Income Tax Disclosure [Abstract]
INCOME TAXES	14. INCOME TAXES The Company operates its business to be qualified to be taxed as a REIT for federal income tax purposes. As a REIT, the Company generally will not be subject to federal income tax on the income that the Company distributes currently to our shareholders. The determination that the Company is a REIT requires analysis of various factual matters and circumstances that may not be totally within its control. To qualify as a REIT, at least 95% of the Company’s gross income must come from specific passive sources, such as rent, that are itemized in REIT tax laws. In addition, to qualify as a REIT, the Company cannot own specified amounts of debt and equity securities of some issuers. The Company is also required to distribute to its shareholders with respect to each year at least 90% of its REIT taxable income (excluding net capital gains). The Company’s intention is to adhere to the REIT qualification requirements and to maintain its qualification for taxation as a REIT. If the Company fails to qualify for taxation as a REIT in any taxable year, the Company will be subject to federal income taxes at regular corporate rates (including any applicable alternative minimum tax) and it may not be able to qualify as a REIT for four subsequent taxable years. As a REIT, the Company may be subject to certain state and local taxes on its income and property, and to federal income and excise taxes on undistributed taxable income. The Company’s taxable REIT subsidiaries ("TRS") will generally be subject to federal, state, and local income taxes at the applicable rates. 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. In projecting future taxable income, the analysis begins with historical results and incorporates assumptions about the amount of future state and federal pretax operating income adjusted for items that do not have tax consequences. The assumptions about future taxable income require significant judgment and are consistent with the plans and estimates the Company is using to manage the underlying businesses. The Company considered all available evidence, both positive and negative, including cumulative loss in recent years and its current forecast of future income in its analysis. While the Company believes its forecast of future taxable income is reasonable, it is inherently uncertain. If the Company’s projections of future income are lower than expected, the Company may need to establish a valuation allowance. Based on the analysis prepared, the Company recorded a deferred tax asset of $1.0 million as of September 30, 2017. There were no deferred tax balances as of September 30, 2016. The Company had no accruals for tax uncertainties as of September 30, 2017 and December 31, 2016.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	15. SUBSEQUENT EVENTS On October 2, 2017, the Company entered into a lease and will commence construction on a 165,000 square foot building at Four Points in Austin, Texas. The project is 100% preleased to a single tenant under a 10-year lease. Estimated costs, including $2.1 million of existing land basis, total $48.2 million, with delivery anticipated in Q1 2019. The Company expects to fund the project with available cash balances and/or funds from its Credit Facility. On October 16, 2017, the Company acquired through ground leases 3025 and 3001 Market Street, known as One Drexel Plaza and Drexel Square, respectively, located in Philadelphia, Pennsylvania, containing 282,709 rentable square feet, for a gross sales price of $35.0 million. The acquisition is an asset acquisition under ASU 2017-01. As such, we capitalized $2.7 million of transaction costs. Under the purchase agreement, the Company is obligated to incur a minimum of $8.0 million to improve One Drexel Plaza and Drexel Square over the next 24 months. On October 18, 2017, DRA (G&I) Austin (the “DRA Austin Venture”), a real estate venture in which the Company holds a 50% interest, sold five office portfolios in Austin, Texas containing 1,164,496 square feet for a gross sales price of $333.3 million. Prior to the sale, the properties were encumbered by $151.0 million of mortgage debt. The Company’s share of cash proceeds, after payment of the DRA Austin Venture’s share of debt, closing costs and prorations was $86.4 million. The Company currently estimates its total gain on the transaction is approximately $52 million.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements have been prepared by the Company pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP") have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, all adjustments (consisting solely of normal recurring matters) for a fair statement of the financial position of the Company as of September 30, 2017, the results of its operations for the three- and nine-month periods ended September 30, 2017 and 2016 and its cash flows for the nine-month periods ended September 30, 2017 and 2016 have been included. The results of operations for such interim periods are not necessarily indicative of the results for a full year. These consolidated financial statements should be read in conjunction with the Parent Company’s and the Operating Partnership’s consolidated financial statements and footnotes included in their combined 2016 Annual Report on Form 10-K filed with the SEC on March 1, 2017. The Company's Annual Report on Form 10-K for the year ended December 31, 2016 contains a discussion of our significant accounting policies under Note 2, "Summary of Significant Accounting Policies".
Significant Accounting Policies – Revenue Recognition	Significant Accounting Policies – Revenue Recognition The Company’s flexible stay revenue consists of room revenue, food and beverage revenue, and revenue from other hotel operating departments (such as parking fees and other guest service fees). These revenues are recorded net of any sales and occupancy taxes collected from the hotel guests. All rebates or discounts are recorded as a reduction to revenue, and there are no material contingent obligations with respect to rebates and discounts offered by the hotel. All revenues are recorded on an accrual basis as they are earned. Any cash received prior to a guest’s arrival is recorded as an advance deposit from the guest and recognized as revenue at the time of the guest's occupancy at the hotel property.
Out Of Period Adjustment	Out of Period Adjustment The Company recorded $1.2 million of impairment charges during quarter ended December 31, 2016, which should have been recorded in the consolidated financial statements for the three-month period ended March 31, 2017 and the nine-month period ended September 30, 2017. Management concluded that these misstatements were not material to any prior period, nor were they material to the consolidated financial statements as of and for the three- and nine-month periods ended September 30, 2017.
Reclassifications	Reclassifications During the first quarter of 2017, the Company adopted ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (“ASU 2016-09”), which requires the Company to reclassify employer tax payments on account of employee tax withholdings on share-based awards from operating activities to financing activities in the consolidated statement of cash flows. Prior to the issuance of ASU 2016-09, there was no guidance on the classification of cash paid by an employer to the taxing authorities when directly withholding shares for tax withholding purposes. As a result of the adoption, a $0.9 million cash outflow has been reclassified in the September 30, 2016 consolidated statements of cash flows from operating activities to financing activities. There was no other impact from the adoption of this guidance. During the quarter ended December 31, 2016, the Company early adopted ASU 2016-15, “Classification of Certain Cash Receipts and Cash Payments” (“ASU 2016-15”), which clarifies that debt prepayment costs should be presented as financing activities in the statement of cash flows. As a result of the adoption, $53.4 million was reclassified in the consolidated statements of cash flows from the operating activities section to the financing activities section of the consolidated statements of cash flows, within the “Repayment of mortgage notes payable” caption, for the nine-months period ended September 30, 2016. There was no other impact from the adoption of this guidance.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2017, the Financial Accounting Standards Board (the “FASB”) issued ASU No. 2017-12 (“ASU 2017-12”) to simplify the application of hedge accounting guidance and improve the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements. In addition, ASU 2017-12 requires an entity to present the earnings effect of the hedging instrument in the same income statement line item in which the earnings effect of the hedged item is reported. The transition guidance provides companies with the option of early adopting the new standard using a modified retrospective transition method in any interim period after issuance of the update, or alternatively requires adoption for fiscal years beginning after December 15, 2018. This adoption method requires companies to recognize the cumulative effect of initially applying the guidance as an adjustment to accumulated other comprehensive income with a corresponding adjustment to the opening balance of retained earnings as of the beginning of the fiscal year that an entity adopts the update. The Company is in the process of evaluating the impact of this new guidance on its consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09 (“ASU 2017-09”) to provide guidance to clarify when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the changes in terms or conditions. ASU 2017-09 is effective for all entities for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. Early adoption is permitted and application is prospective. The Company is in the process of evaluating the impact of this new guidance on its consolidated financial statements. In February 2017, the FASB issued ASU No. 2017-05 (“ASU 2017-05”) to provide guidance for recognizing gains and losses from the transfer of nonfinancial assets and in-substance nonfinancial assets in contracts with non-customers, unless other specific guidance applies. The standard requires a company to derecognize nonfinancial assets once it transfers control of a distinct nonfinancial asset or distinct in substance nonfinancial asset. Additionally, when a company transfers its controlling interest in a nonfinancial asset, but retains a noncontrolling ownership interest, the company is required to measure any noncontrolling interest it receives or retains at fair value. The guidance requires companies to recognize a full gain or loss on the transaction. As a result of the new guidance, the guidance specific to real estate sales in ASC 360-20 will be eliminated. ASU 2017-05 is effective for annual periods beginning after December 15, 2017, including interim periods within that reporting period. The effective date of this guidance coincides with revenue recognition guidance. The Company expects to utilize the modified retrospective approach. Under the modified retrospective approach, the Company is required to evaluate incomplete contracts as of December 31, 2017 to determine if the sale recognition of nonfinancial assets under ASU 2017-05 differs from ASC 360-20. The Company has identified three potential sale contracts that may not be considered completed contracts, as defined under ASU 2017-05 by December 31, 2017. Based on our final assessment of these sale contracts, the revenue and remaining gain on sale for each of these property sales will be recognized when the Company fulfills its performance obligations under each contract. Accordingly, the derecognition of nonfinancial assets and revenue recognition patterns are not expected to change under ASU 2017-05 when compared to ASC 360-20. In May 2016, the FASB issued guidance amending the revenue from contracts with customers standard issued in May 2014, which is not yet effective. The amendments are intended to address implementation issues that were raised by stakeholders and discussed by the Joint Transition Resource Group, and provide additional practical expedients on collectability, noncash consideration, presentation of sales tax and contract modifications and completed contracts at transition. In accordance with the FASB election to defer the effective date of the revenue recognition standard by one year, reporting entities may choose to adopt the standard as of its original effective date or for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Calendar year-end reporting entities are therefore required to apply the new revenue guidance beginning in their 2018 interim and annual financial statements. The Company has evaluated the impact of this new guidance and has determined that the impact of the adoption of this guidance is not material to its financial results. In order to evaluate this standard the Company analyzed all of its revenue streams except for rental revenue because rental revenue recognition is not covered by revenue from contracts with customers. The results of the initial assessment are as follows: • • • •

Real Estate Investments (Tables

Real Estate Investments (Tables)	9 Months Ended
	Sep. 30, 2017
Real Estate Properties [Line Items]
Gross Carrying Value Of Company's Properties	As of September 30, 2017 and December 31, 2016, the gross carrying value of the properties was as follows (in thousands): September 30, December 31, 2017 2016 Land $ 470,391 $ 469,522 Building and improvements 2,846,869 2,683,087 Tenant improvements 451,807 433,686 Operating properties 3,769,067 3,586,295 Assets held for sale - real estate investments (a) 47,291 73,591 Total $ 3,816,358 $ 3,659,886 (a) Real estate investments related to assets held for sale above represents gross real estate assets and does not include accumulated depreciation, land held for development or other assets on the balance sheet of the property held for sale. See “ Held for Sale ” below in this Note 3.
Schedule of Purchase Price Allocation	The purchase price has been allocated as follows (in thousands): July 18, 2017 Building, land and improvements $ 31,728 Intangible assets acquired (a) 2,838 Below market lease liabilities assumed (b) (1,818 ) $ 32,748 (a) Weighted average amortization period of 5.9 years. (b) Weighted average amortization period of 6.0 years.
Dispositions	The Company sold the following twelve office properties, one retail property and one mixed-use property during the nine-month period ended September 30, 2017 (dollars in thousands): Disposition Date Property/Portfolio Name Location Type Number of Properties Rentable Square Feet Sales Price Net Proceeds on Sale Gain/(Loss) on Sale (a) June 27, 2017 Two, Four A, Four B and Five Eves Drive (Evesham Corporate Center) Marlton, NJ Office 4 134,794 $ 9,700 $ 8,650 $ (325 ) (b) June 12, 2017 7000 Midlantic Drive Mount Laurel, NJ Retail 1 10,784 8,200 7,714 1,413 March 30, 2017 200, 210 & 220 Lake Drive East (Woodland Falls) Cherry Hill, NJ Office 3 215,465 19,000 17,771 (249 ) (c) March 15, 2017 Philadelphia Marine Center (Marine Piers) Philadelphia, PA Mixed-use 1 181,900 21,400 11,182 6,498 (d) March 13, 2017 11700, 11710, 11720 & 11740 Beltsville Drive (Calverton) Beltsville, MD Office 3 313,810 9,000 8,354 - (e) February 2, 2017 1200 & 1220 Concord Avenue (Concord Airport Plaza) Concord, CA Office 2 350,256 33,100 32,010 551 (f) Total Dispositions 14 1,207,009 $ 100,400 $ 85,681 $ 7,888 (a) Gain/(Loss) on Sale is net of closing and other transaction related costs. (b) During the first quarter of 2017, the Company recognized a $1.0 million impairment related to these properties. The loss on sale represents closing costs. (c) During the fourth quarter of 2016, the Company recognized a $7.3 million impairment related to these properties. The loss on sale represents closing costs. (d) On March 15, 2017, the Company sold its sublease interest in the Piers at Penn’s Landing (the “Marine Piers”), which includes leasehold improvements containing 181,900 net rentable square feet, and a marina, located in Philadelphia, Pennsylvania for an aggregate sales price of $21.4 million, which will be paid in two installments. On the closing date, the buyer paid $12.0 million in cash. On the second purchase price installment date, the buyer will pay $9.4 million. The second purchase price installment is due on (a) January 31, 2020, in the event that the tenant at the Marine Piers does not exercise its existing option to extend the term of the sublease or (b) January 15, 2024, in the event that the tenant does exercise its current extension option to extend the term of the sublease. In accordance with ASC 360-20, Real Estate Sales (e) During the fourth quarter of 2016, the Company recognized a $3.0 million impairment related to these properties. During the first quarter of 2017, there was a price reduction of $1.7 million under the agreement of sale and an additional impairment of $1.7 million was recognized. (f) During the fourth quarter of 2016, the Company recognized an $11.5 million impairment related to these properties. This sale is designated as a like-kind exchange under Section 1031 of the Internal Revenue Code (“IRC”) and, as such, the proceeds, totaling $32.0 million after closing costs and prorations, were deposited with a Qualified Intermediary, as defined under the IRC. The proceeds received at closing were recorded as “Other assets” in the Company’s consolidated balance sheet. During the third quarter of 2017, the Company acquired 3000 Market Street in Philadelphia, Pennsylvania using the full balance of the Section 1031 proceeds. See “Acquisition” The Company sold the following land parcels during the nine-month period ended September 30, 2017 (dollars in thousands): Disposition Date Property/Portfolio Name Location Number of Parcels Acres Sales Price Net Proceeds on Sale Gain on Sale September 13, 2017 50 E. Swedesford Square Malvern, PA 1 12.0 $ 7,200 $ 7,098 $ 882 July 18, 2017 Bishop's Gate Mount Laurel, NJ 1 49.5 6,000 5,640 71 (a) April 28, 2017 Garza Ranch - Multi-family Austin, TX 1 8.4 11,800 11,560 - (b) February 15, 2017 Gateway Land - Site C Richmond, VA 1 4.8 1,100 1,043 - (c) January 30, 2017 Garza Ranch - Hotel Austin, TX 1 1.7 3,500 3,277 - (b) Total Dispositions 5 76.4 $ 29,600 $ 28,618 $ 953 (a) During the fourth quarter of 2016, the Company recognized an impairment of $3.0 million. During the second quarter of 2017, the Company recognized an additional impairment of $0.3 million, representing closing costs. See “Land Impairment” section below. (b) The Company has a continuing involvement through a completion guaranty, which requires the Company as developer to complete certain infrastructure improvements on behalf of the buyers of the land parcels. The cash received at settlement was recorded as “Deferred income, gains and rent” on the Company’s consolidated balance sheet and the Company will recognize the sale once the infrastructure improvements are complete. See Note 13, Commitments and Contingencies ” for further discussion of the infrastructure improvements. (c) During the fourth quarter of 2016, the Company recognized a nominal impairment related to this land parcel.
Held for Sale Properties Included in Continuing Operations [Member]
Real Estate Properties [Line Items]
Summary of Properties Classified as Held for Sale but Which did not Meet the Criteria to be Classified within Discontinued Operations	The following is a summary of properties classified as held for sale but which did not meet the criteria to be classified within discontinued operations at September 30, 2017 (in thousands): Held for Sale Properties Included in Continuing Operations September 30, 2017 630 Allendale Road - Office (a) Newtown Square - Office (b) Total ASSETS HELD FOR SALE Real estate investments: Operating properties $ 19,482 $ 27,809 $ 47,291 Accumulated depreciation (6,985 ) (9,206 ) (16,191 ) Operating real estate investments, net 12,497 18,603 31,100 Construction-in-progress - 25 25 Total assets held for sale, net $ 12,497 $ 18,628 $ 31,125 LIABILITIES HELD FOR SALE Other liabilities $ 35 $ 234 $ 269 Total liabilities held for sale $ 35 $ 234 $ 269 (a) Office property containing 150,000 rentable square feet located in the Pennsylvania Suburbs segment. (b) Five office properties containing 252,802 rentable square feet located in the Pennsylvania Suburbs segment.

Investment in Unconsolidated 29

Investment in Unconsolidated Real Estate Ventures (Tables)	9 Months Ended
	Sep. 30, 2017
Equity Method Investments And Joint Ventures [Abstract]
Investment in Real Estate Ventures and Share of Real Estate Ventures' Income (Loss)	The following is a summary of the financial position of the Real Estate Ventures in which the Company held interests as of September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Net property $ 1,329,601 $ 1,483,067 Other assets 205,631 231,972 Other liabilities 109,041 129,486 Debt, net 910,842 989,738 Equity 515,349 595,815 Company’s share of equity (Company’s basis) (a) $ 236,313 $ 281,331 (a) This amount includes the effect of the basis difference between the Company's historical cost basis and the basis recorded at the Real Estate Venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from the impairment of investments, purchases of third party interests in existing Real Estate Ventures and upon the transfer of assets that were previously owned by the Company into a Real Estate Venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the Real Estate Venture level. The following is a summary of results of operations of the Real Estate Ventures in which the Company held interests during the three- and nine-month periods ended September 30, 2017 and 2016 (in thousands): Three-month periods ended September 30, Nine-month periods ended September 30, 2017 2016 2017 2016 Revenue $ 56,511 $ 57,710 $ 169,609 $ 157,641 Operating expenses (27,419 ) (27,592 ) (77,757 ) (81,347 ) Provision for impairment - (10,476 ) - (10,476 ) Interest expense, net (11,670 ) (12,102 ) (33,771 ) (32,019 ) Depreciation and amortization (20,684 ) (22,722 ) (61,816 ) (63,125 ) Net loss (a) $ (3,262 ) $ (15,182 ) $ (3,735 ) $ (29,326 ) Equity in loss of Real Estate Ventures (b) $ (5,723 ) $ (7,254 ) $ (5,387 ) $ (9,323 ) (a) The nine-month period ended September (b) The three- and nine-month periods ended September 30, 2017 include a $4.8 million other than temporary impairment charge related to the BDN-AI Venture that was recorded during the three months ended September 30, 2017.

Intangible Assets and Liabili30

Intangible Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets and Liabilities	As of September 30, 2017 and December 31, 2016, the Company’s intangible assets/liabilities were comprised of the following (in thousands): September 30, 2017 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 100,519 $ (45,765 ) $ 54,754 Tenant relationship value 12,831 (10,646 ) 2,185 Above market leases acquired 4,354 (2,476 ) 1,878 Total intangible assets, net $ 117,704 $ (58,887 ) $ 58,817 Acquired lease intangibles, net: Below market leases acquired $ 32,158 $ (15,002 ) $ 17,156 December 31, 2016 Total Cost Accumulated Amortization Intangible Assets, net Intangible assets, net: In-place lease value $ 142,889 $ (75,696 ) $ 67,193 Tenant relationship value 13,074 (10,167 ) 2,907 Above market leases acquired 4,718 (2,340 ) 2,378 Total intangible assets, net $ 160,681 $ (88,203 ) $ 72,478 Acquired lease intangibles, net: Below market leases acquired $ 37,579 $ (19,460 ) $ 18,119
Summary of Amortization for Intangible Assets and Liabilities	As of September 30, 2017, the Company’s annual amortization for its intangible assets/liabilities, assuming no prospective early lease terminations, are as follows (dollars in thousands): Assets Liabilities 2017 (three months remaining) $ 3,443 $ 677 2018 12,257 2,512 2019 10,984 2,198 2020 8,904 1,650 2021 6,366 1,062 Thereafter 16,863 9,057 Total $ 58,817 $ 17,156

Debt Obligations (Tables)

Debt Obligations (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Consolidated debt obligations	The following table sets forth information regarding the Company’s consolidated debt obligations outstanding at September 30, 2017 and December 31, 2016 (in thousands): September 30, 2017 December 31, 2016 Effective Interest Rate Maturity Date MORTGAGE DEBT: Two Logan Square $ 84,839 $ 86,012 3.98% May 2020 One Commerce Square 124,518 127,026 3.64% (a) Apr 2023 Two Commerce Square 112,000 112,000 4.51% (b) Apr 2023 Principal balance outstanding 321,357 325,038 Plus: fair market value premium (discount), net (2,434 ) (2,761 ) Less: deferred financing costs (606 ) (728 ) Mortgage indebtedness $ 318,317 $ 321,549 UNSECURED DEBT $600.0M Revolving Credit Facility $ 178,000 $ - LIBOR + 1.20% May 2019 Seven-Year Term Loan - Swapped to fixed 250,000 250,000 3.72% Oct 2022 $300.0M 5.70% Guaranteed Notes due 2017 (c) - 300,000 5.68% May 2017 $325.0M 4.95% Guaranteed Notes due 2018 325,000 325,000 5.13% Apr 2018 $250.0M 3.95% Guaranteed Notes due 2023 250,000 250,000 4.02% Feb 2023 $250.0M 4.10% Guaranteed Notes due 2024 250,000 250,000 4.33% Oct 2024 $250.0M 4.55% Guaranteed Notes due 2029 250,000 250,000 4.60% Oct 2029 Indenture IA (Preferred Trust I) - Swapped to fixed 27,062 27,062 2.75% Mar 2035 Indenture IB (Preferred Trust I) - Swapped to fixed 25,774 25,774 3.30% Apr 2035 Indenture II (Preferred Trust II) - Swapped to fixed 25,774 25,774 3.09% Jul 2035 Principal balance outstanding 1,581,610 1,703,610 Plus: original issue premium (discount), net (3,937 ) (4,678 ) Less: deferred financing costs (6,350 ) (7,369 ) Total unsecured indebtedness $ 1,571,323 $ 1,691,563 Total Debt Obligations $ 1,889,640 $ 2,013,112 (a) This loan was assumed upon acquisition of the related properties on December 19, 2013. On December 29, 2015, the Company refinanced the debt increasing the principal balance to $130.0 million and extended the scheduled maturity date from January 6, 2016 to April 5, 2023. The effective interest rate as of December 31, 2015 was 3.64%. A default under this loan will also constitute a default under the loan secured by Two Commerce Square. This loan is also secured by a lien on Two Commerce Square. (b) This loan was assumed upon acquisition of the related property on December 19, 2013. The interest rate reflects the market rate at the time of acquisition. A default under this loan will also constitute a default under the loan secured by One Commerce Square. This loan is also secured by a lien on One Commerce Square. (c) On May 1, 2017, the entire principal balance of the unsecured 5.70% Guaranteed Notes was repaid upon maturity. Available cash balances and the Credit Facility (as defined below) were used to fund the repayment of the unsecured notes.
Schedule of Maturities of Long-term Debt	As of September 30, 2017, the Company’s aggregate scheduled principal payments of debt obligations, excluding amortization of discounts and premiums, are as follows (in thousands): 2017 (three months remaining) $ 1,250 2018 331,601 2019 185,360 2020 86,978 2021 6,099 Thereafter 1,291,679 Total principal payments 1,902,967 Net unamortized premiums/(discounts) (6,371 ) Net deferred financing costs (6,956 ) Outstanding indebtedness $ 1,889,640

Fair Value of Financial Instr32

Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Schedule of Financial Instruments With Fair Values Different From Their Carrying Amount	The following are financial instruments for which the Company’s estimates of fair value differ from the carrying amounts (in thousands): September 30, 2017 December 31, 2016 Carrying Amount (a) Fair Value Carrying Amount (a) Fair Value Unsecured notes payable $ 1,066,366 $ 1,087,263 $ 1,364,854 $ 1,372,758 Variable rate debt $ 504,957 $ 486,653 $ 326,709 $ 307,510 Mortgage notes payable $ 318,317 $ 305,657 $ 321,549 $ 328,853 Note receivable (b) $ 3,384 $ 3,655 $ 3,380 $ 3,717 (a) In April 2015, the FASB issued guidance requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct reduction from the carrying amount of the corresponding debt liability, consistent with debt discounts. As a result, the carrying amounts presented in the table above are net of deferred financing costs of $4.7 million and $5.5 million for unsecured notes payable, $1.7 million and $1.9 million for variable rate debt and $0.6 million and $0.7 million for mortgage notes payable as of September 30, 2017 and December 31, 2016, respectively. (b) The inputs to originate the note receivable are unobservable and, as a result, are categorized as Level 3 . The Company determined fair value by calculating the present value of the cash payments to be received through the maturity date of the loan. See Note 2, “Summary of Significant Accounting Policies,” to the Company’s 2016 Annual Report on Form 10-K for the year ended December 31, 2016 for further information regarding the note origination.

Fair Value of Derivative Fina33

Fair Value of Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following table summarizes the terms and fair values of the Company’s derivative financial instruments as of September 30, 2017 and December 31, 2016. 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 and included in other assets and other liabilities on the Company’s consolidated balance sheets). Hedge Product Hedge Type Designation Notional Amount Strike Trade Date Maturity Date Fair value 9/30/2017 12/31/2016 9/30/2017 12/31/2016 (Liabilities)/Assets Swap Interest Rate Cash Flow (a) $ 250,000 $ 250,000 3.718 % October 8, 2015 October 8, 2022 $ (3,185 ) $ 3,733 Swap Interest Rate Cash Flow (a) 25,774 25,774 3.300 % December 22, 2011 January 30, 2021 (209 ) (300 ) Swap Interest Rate Cash Flow (a) 25,774 25,774 3.090 % January 6, 2012 October 30, 2019 (88 ) (214 ) Swap Interest Rate Cash Flow (a) 27,062 27,062 2.750 % December 21, 2011 September 30, 2017 - (83 ) $ 328,610 $ 328,610 (a) Hedging unsecured variable rate debt.

Beneficiaries Equity of the P34

Beneficiaries Equity of the Parent Company (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Earnings Per Share (EPS), Basic and Diluted	The following tables detail the number of shares and net income used to calculate basic and diluted earnings per share (in thousands, except share and per share amounts; results may not add due to rounding): Three-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 19,046 $ 19,046 $ 7,884 $ 7,884 Net income from continuing operations attributable to non-controlling interests (170 ) (170 ) (58 ) (58 ) Nonforfeitable dividends allocated to unvested restricted shareholders (73 ) (73 ) (79 ) (79 ) Preferred share dividends - - (1,725 ) (1,725 ) Net income attributable to common shareholders $ 18,803 $ 18,803 $ 6,022 $ 6,022 Denominator Weighted-average shares outstanding 175,433,657 175,433,657 175,127,110 175,127,110 Contingent securities/Share based compensation - 1,401,365 - 1,237,505 Weighted-average shares outstanding 175,433,657 176,835,022 175,127,110 176,364,615 Earnings per Common Share: Net income attributable to common shareholders $ 0.11 $ 0.11 $ 0.03 $ 0.03 Nine-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 48,015 $ 48,015 $ 52,871 $ 52,871 Net income from continuing operations attributable to non-controlling interests (384 ) (384 ) (425 ) (425 ) Nonforfeitable dividends allocated to unvested restricted shareholders (245 ) (245 ) (263 ) (263 ) Preferred share dividends (2,032 ) (2,032 ) (5,175 ) (5,175 ) Preferred share redemption charge (3,181 ) (3,181 ) - - Net income attributable to common shareholders $ 42,173 $ 42,173 $ 47,008 $ 47,008 Denominator Weighted-average shares outstanding 175,315,581 175,315,581 174,976,998 174,976,998 Contingent securities/Share based compensation - 1,283,751 - 1,032,824 Weighted-average shares outstanding 175,315,581 176,599,332 174,976,998 176,009,822 Earnings per Common Share: Net income attributable to common shareholders $ 0.24 $ 0.24 $ 0.27 $ 0.27

Partners Equity of the Operat35

Partners Equity of the Operating Partnership (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share (EPS), Basic and Diluted	The following tables detail the number of shares and net income used to calculate basic and diluted earnings per share (in thousands, except share and per share amounts; results may not add due to rounding): Three-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 19,046 $ 19,046 $ 7,884 $ 7,884 Net income from continuing operations attributable to non-controlling interests (170 ) (170 ) (58 ) (58 ) Nonforfeitable dividends allocated to unvested restricted shareholders (73 ) (73 ) (79 ) (79 ) Preferred share dividends - - (1,725 ) (1,725 ) Net income attributable to common shareholders $ 18,803 $ 18,803 $ 6,022 $ 6,022 Denominator Weighted-average shares outstanding 175,433,657 175,433,657 175,127,110 175,127,110 Contingent securities/Share based compensation - 1,401,365 - 1,237,505 Weighted-average shares outstanding 175,433,657 176,835,022 175,127,110 176,364,615 Earnings per Common Share: Net income attributable to common shareholders $ 0.11 $ 0.11 $ 0.03 $ 0.03 Nine-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 48,015 $ 48,015 $ 52,871 $ 52,871 Net income from continuing operations attributable to non-controlling interests (384 ) (384 ) (425 ) (425 ) Nonforfeitable dividends allocated to unvested restricted shareholders (245 ) (245 ) (263 ) (263 ) Preferred share dividends (2,032 ) (2,032 ) (5,175 ) (5,175 ) Preferred share redemption charge (3,181 ) (3,181 ) - - Net income attributable to common shareholders $ 42,173 $ 42,173 $ 47,008 $ 47,008 Denominator Weighted-average shares outstanding 175,315,581 175,315,581 174,976,998 174,976,998 Contingent securities/Share based compensation - 1,283,751 - 1,032,824 Weighted-average shares outstanding 175,315,581 176,599,332 174,976,998 176,009,822 Earnings per Common Share: Net income attributable to common shareholders $ 0.24 $ 0.24 $ 0.27 $ 0.27
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings Per Share (EPS), Basic and Diluted	The following tables detail the number of units and net income used to calculate basic and diluted earnings per common partnership unit (in thousands, except unit and per unit amounts; results may not add due to rounding): Three-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 19,046 $ 19,046 $ 7,884 $ 7,884 Nonforfeitable dividends allocated to unvested restricted unitholders (73 ) (73 ) (79 ) (79 ) Preferred unit dividends - - (1,725 ) (1,725 ) Net income attributable to non-controlling interests (12 ) (12 ) (6 ) (6 ) Net income attributable to common unitholders $ 18,961 $ 18,961 $ 6,074 $ 6,074 Denominator Weighted-average units outstanding 176,913,456 176,913,456 176,606,909 176,606,909 Contingent securities/Share based compensation - 1,401,365 - 1,237,505 Total weighted-average units outstanding 176,913,456 178,314,821 176,606,909 177,844,414 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.11 $ 0.11 $ 0.03 $ 0.03 Nine-month periods ended September 30, 2017 2016 Basic Diluted Basic Diluted Numerator Income from continuing operations $ 48,015 $ 48,015 $ 52,871 $ 52,871 Nonforfeitable dividends allocated to unvested restricted unitholders (245 ) (245 ) (263 ) (263 ) Preferred unit dividends (2,032 ) (2,032 ) (5,175 ) (5,175 ) Preferred unit redemption charge (3,181 ) (3,181 ) - - Net income attributable to non-controlling interests (26 ) (26 ) (12 ) (12 ) Net income attributable to common unitholders $ 42,531 $ 42,531 $ 47,421 $ 47,421 Denominator Weighted-average units outstanding 176,795,380 176,795,380 176,491,311 176,491,311 Contingent securities/Share based compensation - 1,283,751 - 1,032,824 Total weighted-average units outstanding 176,795,380 178,079,131 176,491,311 177,524,135 Earnings per Common Partnership Unit: Net income attributable to common unitholders $ 0.24 $ 0.24 $ 0.27 $ 0.27

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Real Estate Investments, Net Operating Income and Unconsolidated Real Estate Ventures of Reportable Segments	The following tables provide selected asset information and results of operations of the Company's reportable segments (in thousands): Real estate investments, at cost: September 30, 2017 December 31, 2016 Philadelphia CBD $ 1,591,828 $ 1,320,974 Pennsylvania Suburbs (a) 966,128 1,005,446 Metropolitan Washington, D.C. 976,286 975,987 Austin, Texas 146,859 146,794 Other 87,966 137,094 $ 3,769,067 $ 3,586,295 Assets held for sale (b) 47,291 73,591 Operating properties $ 3,816,358 $ 3,659,886 Corporate Construction-in-progress $ 127,141 $ 297,462 Land held for development $ 120,696 $ 150,970 (a) As of September 30, 2017, the Company categorized (b) Real estate investments related to assets held for sale above represents gross real estate assets and does not include accumulated “Real Estate Investments,” None of the above aforementioned sales or properties classified as held for sale are considered significant dispositions under the accounting guidance for discontinued operations. Net operating income (in thousands): Three-month periods ended September 30, 2017 2016 Total revenue Operating expenses (a) Net operating income (loss) Total revenue Operating expenses (a) Net operating income Philadelphia CBD $ 56,452 $ (22,010 ) $ 34,442 $ 50,744 $ (19,071 ) $ 31,673 Pennsylvania Suburbs 34,861 (11,846 ) 23,015 35,763 (11,247 ) 24,516 Metropolitan Washington, D.C. 23,079 (8,500 ) 14,579 24,251 (9,900 ) 14,351 Austin, Texas 7,886 (3,929 ) 3,957 8,726 (3,523 ) 5,203 Other 3,752 (2,647 ) 1,105 8,526 (4,837 ) 3,689 Corporate 2,408 (1,769 ) 639 1,684 (2,739 ) (1,055 ) Operating properties $ 128,438 $ (50,701 ) $ 77,737 $ 129,694 $ (51,317 ) $ 78,377 Nine-month periods ended September 30, 2017 2016 Total revenue Operating expenses (a) Net operating income Total revenue Operating expenses (a) Net operating income Philadelphia CBD $ 165,352 $ (64,311 ) $ 101,041 $ 148,496 $ (58,102 ) $ 90,394 Pennsylvania Suburbs 105,673 (35,670 ) 70,003 107,971 (36,982 ) 70,989 Metropolitan Washington, D.C. 69,190 (26,347 ) 42,843 76,881 (29,567 ) 47,314 Austin, Texas 25,772 (11,634 ) 14,138 25,123 (9,689 ) 15,434 Other 14,274 (9,083 ) 5,191 30,328 (17,513 ) 12,815 Corporate 6,888 (5,355 ) 1,533 4,578 (4,460 ) 118 Operating properties $ 387,149 $ (152,400 ) $ 234,749 $ 393,377 $ (156,313 ) $ 237,064 (a) Includes property operating expense, real estate taxes and third party management expense. Unconsolidated real estate ventures (in thousands): Investment in real estate ventures, at equity Equity in income (loss) of real estate ventures As of Three-month periods ended September 30, Nine-month periods ended September 30, September 30, 2017 December 31, 2016 2017 2016 2017 2016 Philadelphia CBD $ 42,298 $ 48,691 $ 134 $ (453 ) $ 113 $ (473 ) Pennsylvania Suburbs 3,320 15,421 24 (170 ) 448 410 Metropolitan Washington, D.C. (a) 119,550 141,786 (5,264 ) (5,287 ) (4,872 ) (6,068 ) Austin, Texas 52,940 52,886 (15 ) (561 ) 1,266 (1,299 ) MAP Venture (b) 16,283 20,893 (706 ) (1,010 ) (2,610 ) (2,608 ) Other 1,922 1,654 104 227 268 715 Total $ 236,313 $ 281,331 $ (5,723 ) $ (7,254 ) $ (5,387 ) $ (9,323 ) (a) The three- and nine-month periods ended September 30, 2017 include a $4.8 million other than temporary impairment charge related to the BDN - AI Venture that was recorded during the three months ended September 30, 2017. (b) The MAP Venture represents a joint venture formed between the Company and MAP Ground Lease Holdings LLC, an affiliate of Och-Ziff Capital Management Group, LLC, on February 4, 2016. The MAP Venture’s business operations, including properties in Richmond, Virginia; Metropolitan Washington, D.C.; New Jersey/Delaware and Pennsylvania Suburbs, are centrally managed with the results reported to management of the Company on a consolidated basis. As a result, the investment in the MAP Venture is separately presented. All other unconsolidated real estate ventures are managed consistently with the Company’s regional segments.
Reconciliation of Consolidated Net Income to Consolidated NOI	The following is a reconciliation of consolidated net income, as defined by GAAP, to consolidated NOI, (in thousands): Three-month periods ended September 30, Nine-month periods ended September 30, 2017 2016 2017 2016 Net income $ 19,046 $ 7,884 $ 48,015 $ 52,871 Plus: Interest expense 19,732 20,814 61,473 64,334 Interest expense - amortization of deferred financing costs 577 645 1,807 2,063 Interest expense - financing obligation - 156 - 679 Depreciation and amortization 42,429 46,956 132,584 142,736 General and administrative expenses 5,813 5,515 21,797 20,711 Equity in loss of Real Estate Ventures 5,723 7,254 5,387 9,323 Provision for impairment - - 3,057 13,069 Loss on early extinguishment of debt - - - 66,590 Less: Interest income 79 291 635 970 Income tax benefit 793 - 1,032 - Net gain (loss) on disposition of real estate - (104 ) 8,411 114,625 Net gain on sale of undepreciated real estate 953 188 953 188 Net gain on Real Estate Venture transactions 13,758 10,472 28,340 19,529 Consolidated net operating income $ 77,737 $ 78,377 $ 234,749 $ 237,064

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Minimum Future Rental Payments on Non-cancelable Leases	Minimum future rental payments on non-cancelable leases at September 30, 2017 are as follows (in thousands): Year Minimum Rent 2017 (three months remaining) $ 303 2018 1,211 2019 1,211 2020 1,211 2021 1,211 Thereafter 57,527 Total $ 62,674

Organization of The Parent Co38

Organization of The Parent Company and The Operating Partnership (Textual) (Details) - Sep. 30, 2017 ft² in Millions	Total	property	ft²	Real_Estate_Investment	a	Apartment_unit
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Properties		97
Office Properties [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Properties		82
Mixed Use Properties [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Properties		4
Retail Properties [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Properties		1
Core Properties [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Properties		87
Development Property [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Properties		1
Redevelopment Properties [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Properties		3
Assets Held-for-sale [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Properties		6
Unconsolidated Real Estate Ventures [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment				13
Unconsolidated Real Estate Ventures [Member] | Seven Real Estate Ventures [Member] | Office Properties [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment				7
Rentable Square Feet | ft²			7.8
Unconsolidated Real Estate Ventures [Member] | Four Real Estate Ventures [Member] | Land Held For Development [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment				4
Acreage of land | a					5.7
Unconsolidated Real Estate Ventures [Member] | Two Other Real Estate Ventures [Member] | Residential Tower One [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment				1
Number of Property units		345				345
Unconsolidated Real Estate Ventures [Member] | Two Other Real Estate Ventures [Member] | Residential Tower Two [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment				1
Number of Property units		321				321
Parent Company [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Ownership in the Operating Partnership	99.20%
Net Rentable Square Feet | ft²			16.4
Area Owned by Company of Undeveloped Parcels of Land | a					214
Area of Additional Undeveloped Parcels of Land With Option to Purchase | a					60
Total Potential Development Capacity | ft²			15.7
Wholly-owned Management Company Subsidiaries [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Net Rentable Square Feet | ft²			26.4
Wholly-owned Management Company Subsidiaries [Member] | Partially Owned Properties [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Net Rentable Square Feet | ft²			10
Wholly-owned Management Company Subsidiaries [Member] | Wholly Owned Properties [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Net Rentable Square Feet | ft²			16.4
Wholly-owned Management Company Subsidiaries [Member] | Office and Industrial Properties [Member] | Partially Owned Properties [Member]
Organization of The Parent Company and The Operating Partnership [Line Items]
Net Rentable Square Feet | ft²			10

Basis of Presentation (Textual)

Basis of Presentation (Textual) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Dec. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Basis Of Presentation [Line Items]
Shares used for employee taxes upon vesting of share awards		$ 674	$ 879
ASU 2016-09 [Member] | Reclassified from Operating Activities to Financing Activities [Member]
Basis Of Presentation [Line Items]
Shares used for employee taxes upon vesting of share awards			900
ASU 2016-15 [Member] | Reclassified from Operating Activities to Financing Activities [Member]
Basis Of Presentation [Line Items]
Debt prepayment costs			$ 53,400
Impairment Charges [Member]
Basis Of Presentation [Line Items]
Out-of-period error immaterial in current year	$ 1,200

Real Estate Investments - Gross

Real Estate Investments - Gross Carrying Value of Properties (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment, Gross [Abstract]
Land		$ 470,391	$ 469,522
Tenant improvements		451,807	433,686
Operating properties		3,769,067	3,586,295
Assets held for sale - real estate investments	[1],[2]	47,291	73,591
Total		3,816,358	3,659,886
Building and Improvements [Member]
Property, Plant and Equipment, Gross [Abstract]
Operating properties		$ 2,846,869	$ 2,683,087
[1]	Real estate investments related to assets held for sale above represents gross real estate assets and does not include accumulated depreciation, land held for development or other assets on the balance sheet of the property held for sale. See Note 3, “Real Estate Investments,” for further information.
[2]	Real estate investments related to assets held for sale above represents gross real estate assets and does not include accumulated depreciation, land held for development or other assets on the balance sheet of the property held for sale. See “Held for Sale” below in this Note 3.

Real Estate Investments - Acqui

Real Estate Investments - Acquisitions (Textual) (Details) $ in Thousands	Jul. 28, 2017USD ($)ft²	Sep. 30, 2017USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)
Business Acquisition [Line Items]
Revenue			$ 128,438	$ 129,694	$ 387,149	$ 393,377
3000 Market Street [Member]
Business Acquisition [Line Items]
Acquisition of office building from unaffiliated third party, cost	$ 32,700
Capitalized acquisition related cost	700
Contractual sale price of real estate acquired	$ 32,000
Revenue		$ 300
3000 Market Street [Member] | Office Properties [Member]
Business Acquisition [Line Items]
Area of Real Estate Property | ft²	58,587

Real Estate Investments - Purch

Real Estate Investments - Purchase Price Allocation (Details) - 3000 Market Street [Member] $ in Thousands	Jul. 18, 2017USD ($)
Business Acquisition [Line Items]
Building, land and improvements	$ 31,728
Intangible assets acquired	2,838	[1]
Below market lease liabilities assumed	(1,818)	[2]
Total purchase price	$ 32,748
[1]	Weighted average amortization period of 5.9 years.
[2]	Weighted average amortization period of 6.0 years.

Real Estate Investments - Pur43

Real Estate Investments - Purchase Price Allocation (Parenthetical) (Details) - 3000 Market Street [Member]	Jul. 18, 2017
Intangible Assets Acquired [Member]
Business Acquisition [Line Items]
Weighted average amortization period	5 years 10 months 25 days
Below Market Lease [Member]
Business Acquisition [Line Items]
Weighted average amortization period	6 years

Real Estate Investments - Dispo

Real Estate Investments - Dispositions (Textual) (Details)		3 Months Ended					6 Months Ended	9 Months Ended
		Sep. 30, 2017USD ($)aproperty	Jun. 30, 2017USD ($)aParcel	Mar. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)aproperty	Sep. 30, 2016USD ($)	Jun. 30, 2017USD ($)aParcel	Sep. 30, 2017USD ($)aproperty	Sep. 30, 2016USD ($)
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net gain (loss) on disposition of real estate		$ 0				$ (104,000)		$ 8,411,000	$ 114,625,000
Number of Properties | property		97						97
Assets held for sale, net		$ 31,125,000			$ 41,718,000			$ 31,125,000
Impairment charges		0				$ 0		3,057,000	$ 13,069,000
Aggregate carrying values of properties		$ 3,769,067,000			3,586,295,000			3,769,067,000
Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net gain (loss) on disposition of real estate								$ 953,000
Acreage of land | a		76.4						76.4
Assets Held-for-sale [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties | property		6						6
Assets held for sale, net		$ 31,125,000						$ 31,125,000
Assets Held-for-sale [Member] | Operating Real Estate Investments, Net [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Assets held for sale, net					40,700,000
Assets Held-for-sale [Member] | Land Held For Development [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Assets held for sale, net					$ 1,000,000
Other Segments
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties | segment				4
Impairment charges		0
Carrying value of real estate prior to impairment		10,200,000						10,200,000
Impairment of properties held for use				$ 1,000,000
Impairment Hold Period				10 years
Residual Capitalization Rates				9.00%
Discount Rates				9.25%
Other Segments | Impairment on Held for Use Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Aggregate carrying values of properties		9,200,000						9,200,000
Other Segments | Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Impairment charges		$ 0
Other Segments | Assets Held-for-sale [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Provision for impairment on assets held for sale								0
Acreage of land | a					5
2970 Market Street (Cira Square) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net gain (loss) on disposition of real estate				$ 500,000
Bishops Gate [Member] | Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net gain (loss) on disposition of real estate	[1]							$ 71,000
Provision for impairment on assets held for sale			$ 300,000		$ 3,000,000
Acreage of land | a		49.5						49.5
Bishops Gate [Member] | Other Segments | Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Provision for impairment on assets held for sale							$ 300,000
Acreage of land | a			50				50
Number of Parcels | Parcel			1				1
Carrying value of real estate prior to impairment			$ 5,900,000				$ 5,900,000
Aggregate carrying value			$ 5,600,000				$ 5,600,000
Office Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property								12
Number of Properties | property		82						82
Office Properties [Member] | Other Segments | Assets Held-for-sale [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties | property					2
Office Properties [Member] | Metropolitan DC [Member] | Assets Held-for-sale [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties | property					3
Retail Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property								1
Mixed-use Property [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property								1
[1]	During the fourth quarter of 2016, the Company recognized an impairment of $3.0 million. During the second quarter of 2017, the Company recognized an additional impairment of $0.3 million, representing closing costs. See “Land Impairment” section below.

Real Estate Investments - Summa

Real Estate Investments - Summary of Office Properties Sold (Details) $ in Thousands		Feb. 02, 2017property	Sep. 30, 2017USD ($)ft²	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)ft²property	Sep. 30, 2016USD ($)
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Net Proceeds on Sale					$ 114,821	$ 758,931
Gain (Loss) on Sale			$ 0	$ (104)	$ 8,411	$ 114,625
Philadelphia Marine Center (Marine Piers) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Rentable Square Feet | ft²			181,900		181,900
Sales Price			$ 21,400		$ 21,400
Net Proceeds on Sale					11,200
Gain (Loss) on Sale					$ 6,500
Office Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property					12
Office Properties [Member] | Two, Four A, Four B and Five Eves Drive (Evesham Corporate Center) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property					4
Rentable Square Feet | ft²			134,794		134,794
Sales Price			$ 9,700		$ 9,700
Net Proceeds on Sale					8,650
Gain (Loss) on Sale	[1],[2]				$ (325)
Office Properties [Member] | 200, 210 & 220 Lake Drive East (Woodland Falls) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property					3
Rentable Square Feet | ft²			215,465		215,465
Sales Price			$ 19,000		$ 19,000
Net Proceeds on Sale					17,771
Gain (Loss) on Sale	[2],[3]				$ (249)
Office Properties [Member] | 11700, 11710, 11720 & 11740 Beltsville Drive (Calverton) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property					3
Rentable Square Feet | ft²			313,810		313,810
Sales Price			$ 9,000		$ 9,000
Net Proceeds on Sale					8,354
Gain (Loss) on Sale	[2],[4]				$ 0
Office Properties [Member] | 1200 & 1220 Concord Avenue (Concord Airport Plaza) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property		2			2
Rentable Square Feet | ft²			350,256		350,256
Sales Price			$ 33,100		$ 33,100
Net Proceeds on Sale					32,010
Gain (Loss) on Sale	[2],[5]				$ 551
Retail Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property					1
Retail Properties [Member] | 7000 Midlantic Drive [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property					1
Rentable Square Feet | ft²			10,784		10,784
Sales Price			$ 8,200		$ 8,200
Net Proceeds on Sale					7,714
Gain (Loss) on Sale	[2]				$ 1,413
Mixed Use Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property					1
Mixed Use Properties [Member] | Philadelphia Marine Center (Marine Piers) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property					1
Rentable Square Feet | ft²			181,900		181,900
Sales Price			$ 21,400		$ 21,400
Net Proceeds on Sale					11,182
Gain (Loss) on Sale	[2],[6]				$ 6,498
Office, Retail and Mixed-use Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties Sold | property					14
Rentable Square Feet | ft²			1,207,009		1,207,009
Sales Price			$ 100,400		$ 100,400
Net Proceeds on Sale					85,681
Gain (Loss) on Sale	[2]				$ 7,888
[1]	During the first quarter of 2017, the Company recognized a $1.0 million impairment related to these properties.
[2]	Gain/(Loss) on Sale is net of closing and other transaction related costs.
[3]	During the fourth quarter of 2016, the Company recognized a $7.3 million impairment related to these properties.
[4]	During the fourth quarter of 2016, the Company recognized a $3.0 million impairment related to these properties. During the first quarter of 2017, there was a price reduction of $1.7 million under the agreement of sale and an additional impairment of $1.7 million was recognized.
[5]	During the fourth quarter of 2016, the Company recognized an $11.5 million impairment related to these properties. This sale is designated as a like-kind exchange under Section 1031 of the Internal Revenue Code (“IRC”) and, as such, the proceeds, totaling $32.0 million after closing costs and prorations, were deposited with a Qualified Intermediary, as defined under the IRC. The proceeds received at closing were recorded as “Other assets” in the Company’s consolidated balance sheet. During the third quarter of 2017, the Company acquired 3000 Market Street in Philadelphia, Pennsylvania using the full balance of the Section 1031 proceeds. See “Acquisition” section above.
[6]	On March 15, 2017, the Company sold its sublease interest in the Piers at Penn’s Landing (the “Marine Piers”), which includes leasehold improvements containing 181,900 net rentable square feet, and a marina, located in Philadelphia, Pennsylvania for an aggregate sales price of $21.4 million, which will be paid in two installments. On the closing date, the buyer paid $12.0 million in cash. On the second purchase price installment date, the buyer will pay $9.4 million. The second purchase price installment is due on (a) January 31, 2020, in the event that the tenant at the Marine Piers does not exercise its existing option to extend the term of the sublease or (b) January 15, 2024, in the event that the tenant does exercise its current extension option to extend the term of the sublease. In accordance with ASC 360-20, Real Estate Sales, the Company determined that it is appropriate to account for the sales transaction under the cost recovery method. The Company received cash proceeds of $11.2 million, after closing costs and prorations, and the net book value of the Marine Piers was $4.7 million, resulting in a gain on sale of $6.5 million. The remaining gain on sale of $9.4 million will be recognized on the second purchase price installment date. The Marine Piers was classified as mixed-use within the Company’s property count.

Real Estate Investments - Sum46

Real Estate Investments - Summary of Office Properties Sold (Parenthetical) (Details) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2017USD ($)ft²	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)ft²Installment	Sep. 30, 2016USD ($)
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Proceeds from the sale of properties					$ 114,821	$ 758,931
Assets held for sale, net	$ 31,125		$ 41,718		31,125
Net gain (loss) on disposition of real estate	$ 0			$ (104)	$ 8,411	$ 114,625
Two, Four A, Four B and Five Eves Drive (Evesham Corporate Center) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Provision for impairment on assets held for sale		$ 1,000
200, 210 & 220 Lake Drive East (Woodland Falls) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Provision for impairment on assets held for sale			7,300
Philadelphia Marine Center (Marine Piers) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Rentable Square Feet | ft²	181,900				181,900
Aggregate sales price	$ 21,400				$ 21,400
Number of installments | Installment					2
First installment payment					$ 12,000
Second installment payment	9,400				$ 9,400
Date of second installment payment					Jan. 31, 2020
Proceeds from the sale of properties					$ 11,200
Assets held for sale, net		4,700
Net gain (loss) on disposition of real estate					6,500
Deferred gain on sale	$ 9,400				9,400
11700, 11710, 11720 & 11740 Beltsville Drive (Calverton) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Provision for impairment on assets held for sale		1,700	3,000
Purchase price reduction		$ 1,700
1200 & 1220 Concord Avenue (Concord Airport Plaza) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Provision for impairment on assets held for sale			$ 11,500
Proceeds after closing costs and prorations					$ 32,000

Real Estate Investments - Sum47

Real Estate Investments - Summary of Land Parcels Sold (Details) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017USD ($)aParcel	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)aParcel	Sep. 30, 2016USD ($)
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Proceeds from the sale of properties				$ 114,821	$ 758,931
Gain on Sale		$ 0	$ (104)	$ 8,411	$ 114,625
Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Parcels | Parcel		5		5
Acreage of land | a		76.4		76.4
Sales Price		$ 29,600		$ 29,600
Proceeds from the sale of properties				28,618
Gain on Sale				$ 953
50 E. Swedesford Square [Member] | Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Parcels | Parcel		1		1
Acreage of land | a		12		12
Sales Price		$ 7,200		$ 7,200
Proceeds from the sale of properties				7,098
Gain on Sale				$ 882
Bishops Gate [Member] | Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Parcels | Parcel		1		1
Acreage of land | a		49.5		49.5
Sales Price		$ 6,000		$ 6,000
Proceeds from the sale of properties				5,640
Gain on Sale	[1]			$ 71
Garza Ranch - Multi-family [Member] | Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Parcels | Parcel		1		1
Acreage of land | a		8.4		8.4
Sales Price		$ 11,800		$ 11,800
Proceeds from the sale of properties				11,560
Gain on Sale	[2]			$ 0
Gateway Land - Site C [Member] | Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Parcels | Parcel		1		1
Acreage of land | a		4.8		4.8
Sales Price		$ 1,100		$ 1,100
Proceeds from the sale of properties				1,043
Gain on Sale	[3]			$ 0
Garza Ranch - Hotel [Member] | Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Parcels | Parcel		1		1
Acreage of land | a		1.7		1.7
Sales Price		$ 3,500		$ 3,500
Proceeds from the sale of properties				3,277
Gain on Sale	[2]			$ 0
[1]	During the fourth quarter of 2016, the Company recognized an impairment of $3.0 million. During the second quarter of 2017, the Company recognized an additional impairment of $0.3 million, representing closing costs. See “Land Impairment” section below.
[2]	The Company has a continuing involvement through a completion guaranty, which requires the Company as developer to complete certain infrastructure improvements on behalf of the buyers of the land parcels. The cash received at settlement was recorded as “Deferred income, gains and rent” on the Company’s consolidated balance sheet and the Company will recognize the sale once the infrastructure improvements are complete. See Note 13, “Commitments and Contingencies” for further discussion of the infrastructure improvements.
[3]	During the fourth quarter of 2016, the Company recognized a nominal impairment related to this land parcel.

Real Estate Investments - Sum48

Real Estate Investments - Summary of Land Parcels Sold (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Bishops Gate [Member] | Land [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Provision for impairment on assets held for sale	$ 0.3	$ 3

Real Estate Investments - Sum49

Real Estate Investments - Summary of Properties Classified as Held for Sale Included in Continuing Operations (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
ASSETS HELD FOR SALE
Total assets held for sale, net		$ 31,125	$ 41,718
LIABILITIES HELD FOR SALE
Total liabilities held for sale		269	$ 81
Held for Sale Properties Included in Continuing Operations [Member]
ASSETS HELD FOR SALE
Operating properties		47,291
Accumulated depreciation		(16,191)
Operating real estate investments, net		31,100
Construction-in-progress		25
Total assets held for sale, net		31,125
LIABILITIES HELD FOR SALE
Other liabilities		269
Total liabilities held for sale		269
Held for Sale Properties Included in Continuing Operations [Member] | 630 Allendale Road - Office [Member]
ASSETS HELD FOR SALE
Operating properties	[1]	19,482
Accumulated depreciation	[1]	(6,985)
Operating real estate investments, net	[1]	12,497
Construction-in-progress	[1]	0
Total assets held for sale, net	[1]	12,497
LIABILITIES HELD FOR SALE
Other liabilities	[1]	35
Total liabilities held for sale	[1]	35
Held for Sale Properties Included in Continuing Operations [Member] | Newtown Square - Office [Member]
ASSETS HELD FOR SALE
Operating properties	[2]	27,809
Accumulated depreciation	[2]	(9,206)
Operating real estate investments, net	[2]	18,603
Construction-in-progress	[2]	25
Total assets held for sale, net	[2]	18,628
LIABILITIES HELD FOR SALE
Other liabilities	[2]	234
Total liabilities held for sale	[2]	$ 234
[1]	Office property containing 150,000 rentable square feet located in the Pennsylvania Suburbs segment.
[2]	Five office properties containing 252,802 rentable square feet located in the Pennsylvania Suburbs segment.

Real Estate Investments - Sum50

Real Estate Investments - Summary of Properties Classified as Held for Sale Included in Continuing Operations (Parenthetical) (Details)	Sep. 30, 2017ft²property
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties	97
Office Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties	82
Held for Sale Properties Included in Continuing Operations [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties	6
Held for Sale Properties Included in Continuing Operations [Member] | Pennsylvania Suburbs [Member] | Office Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Number of Properties	6
Held for Sale Properties Included in Continuing Operations [Member] | Pennsylvania Suburbs [Member] | 630 Allendale Road - Office [Member] | Office Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Rentable Square Feet | ft²	150,000
Held for Sale Properties Included in Continuing Operations [Member] | Pennsylvania Suburbs [Member] | Newtown Square - Office [Member] | Office Properties [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Rentable Square Feet | ft²	252,802
Number of Properties	5

Investment in Unconsolidated 51

Investment in Unconsolidated Real Estate Ventures (Textual) (Details)		Sep. 14, 2017USD ($)ft²property	Jan. 31, 2017USD ($)property	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)property	Sep. 30, 2016USD ($)	Sep. 30, 2017	Sep. 30, 2017property	Sep. 30, 2017ft²	Sep. 30, 2017Real_Estate_Investment	Sep. 30, 2017a	Sep. 30, 2017Apartment_unit	Dec. 31, 2016USD ($)	Jul. 10, 2012ft²property	Dec. 20, 2011ft²property
Schedule Of Equity Method Investments [Line Items]
Investment in Real Estate Ventures, equity method				$ 236,313,000		$ 236,313,000								$ 281,331,000
Management fees				6,918,000	$ 6,248,000	20,483,000	$ 17,691,000
Accounts receivable				14,785,000		14,785,000								12,446,000
Proceeds from the sale of properties						114,821,000	758,931,000
Cash proceeds after the payment of share of the debt and closing costs						59,022,000	20,551,000
Net gain on Real Estate Venture transactions				13,758,000	10,472,000	28,340,000	19,529,000
1919 Venture [Member]
Schedule Of Equity Method Investments [Line Items]
Guarantees, maximum exposure amount				88,900,000		$ 88,900,000
TB-BDN Plymouth Apartments [Member]
Schedule Of Equity Method Investments [Line Items]
Gross sales price			$ 100,500,000
Sale of ownership interest percentage			50.00%
Allocated gross sales value of ownership interest, percentage			50.00%
Number of Properties Sold | property			398
Guarantee obligations cancelled			$ 3,200,000
Cash proceeds after the payment of share of the debt and closing costs			27,200,000
Net gain on Real Estate Venture transactions			14,600,000
TB-BDN Plymouth Apartments [Member] | Pennsylvania [Member]
Schedule Of Equity Method Investments [Line Items]
Construction Loan			54,000,000
Office Properties [Member]
Schedule Of Equity Method Investments [Line Items]
Number of Properties Sold | property						12
Office Properties [Member] | 7101 Wisconsin Property Sale [Member]
Schedule Of Equity Method Investments [Line Items]
Rentable Square Feet | ft²															510,202	587,317
Number of office properties acquired | property															3
Real Estate Venture [Member]
Schedule Of Equity Method Investments [Line Items]
Management fees				1,700,000	1,700,000	$ 4,900,000	4,800,000
Accounts receivable				1,100,000		1,100,000								1,400,000
Real Estate Venture [Member] | Lease Commission Income [Member]
Schedule Of Equity Method Investments [Line Items]
Management fees				400,000	$ 800,000	3,300,000	$ 1,900,000
Unconsolidated Real Estate Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment											13
Investment in Real Estate Ventures, equity method	[1]			236,313,000		236,313,000								$ 281,331,000
Real estate ventures aggregate indebtedness to third parties				915,000,000		915,000,000
Unconsolidated Real Estate Ventures [Member] | TB-BDN Plymouth Apartments [Member]
Schedule Of Equity Method Investments [Line Items]
Equity in income (loss) of Real Estate Ventures			$ 12,600,000
Unconsolidated Real Estate Ventures [Member] | Minimum [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment percentage								20.00%
Unconsolidated Real Estate Ventures [Member] | Maximum [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment percentage								70.00%
Unconsolidated Real Estate Ventures [Member] | Seven Real Estate Ventures [Member] | Office Properties [Member]
Schedule Of Equity Method Investments [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment											7
Rentable Square Feet | ft²										7,800,000
Unconsolidated Real Estate Ventures [Member] | Four Real Estate Ventures [Member] | Land Held For Development [Member]
Schedule Of Equity Method Investments [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment											4
Acreage of land | a												5.7
Unconsolidated Real Estate Ventures [Member] | Two Other Real Estate Ventures [Member] | Residential Tower One [Member]
Schedule Of Equity Method Investments [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment											1
Number of Property units									345				345
Unconsolidated Real Estate Ventures [Member] | Two Other Real Estate Ventures [Member] | Residential Tower Two [Member]
Schedule Of Equity Method Investments [Line Items]
Number of Unconsolidated Investments in Real Estate Ventures | Real_Estate_Investment											1
Number of Property units									321				321
BDN - Al Venture [Member]
Schedule Of Equity Method Investments [Line Items]
Investment in Real Estate Ventures, equity method				44,300,000		44,300,000
Rentable Square Feet | ft²		874,479
Equity method investment percentage																50.00%
Number of office properties owned | property		5							5
Cost of equity method investment		$ 49,100,000		49,100,000		49,100,000
Equity method investment other than temporary impairment charge				4,800,000		$ 4,800,000
Impairment Hold Period						10 years
Residual Capitalization Rates						7.50%
BDN - Al Venture [Member] | 7101 Wisconsin Property Sale [Member]
Schedule Of Equity Method Investments [Line Items]
Rentable Square Feet | ft²		230,904
Equity method investment percentage		50.00%
Gross sales price		$ 105,700,000
Property encumbered at the time of venture sale		37,400,000
Debt instrument prepayment penalty		800,000
Cash proceeds received from sale of venture		63,600,000
Proceeds from the sale of properties		31,800,000
Gains on sales of real estate		$ 13,800,000
BDN - Al Venture [Member] | Current Creek Investments, LLC [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment percentage																50.00%
BDN - Al Venture [Member] | Minimum [Member]
Schedule Of Equity Method Investments [Line Items]
Discount Rates						7.80%
BDN - Al Venture [Member] | Maximum [Member]
Schedule Of Equity Method Investments [Line Items]
Discount Rates						8.50%
BDN - Al Venture [Member] | Office Properties [Member] | 7101 Wisconsin Property Sale [Member]
Schedule Of Equity Method Investments [Line Items]
Number of office properties owned | property																6
Number of office properties upon formation | property																3
Number of office properties subsequent to formation | property																3
evo at Cira Centre South Venture [Member]
Schedule Of Equity Method Investments [Line Items]
Guarantees, maximum exposure amount				55,400,000		$ 55,400,000
PJP VII [Member]
Schedule Of Equity Method Investments [Line Items]
Guarantees, maximum exposure amount				$ 400,000		$ 400,000
[1]	This amount includes the effect of the basis difference between the Company's historical cost basis and the basis recorded at the Real Estate Venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from the impairment of investments, purchases of third party interests in existing Real Estate Ventures and upon the transfer of assets that were previously owned by the Company into a Real Estate Venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the Real Estate Venture level.

Investment in Unconsolidated 52

Investment in Unconsolidated Real Estate Ventures - Summary of Financial Position of Real Estate Ventures (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Schedule Of Equity Method Investments [Line Items]
Company’s share of equity (Company’s basis)		$ 236,313	$ 281,331
Unconsolidated Real Estate Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Net property		1,329,601	1,483,067
Other assets		205,631	231,972
Other liabilities		109,041	129,486
Debt, net		910,842	989,738
Equity		515,349	595,815
Company’s share of equity (Company’s basis)	[1]	$ 236,313	$ 281,331
[1]	This amount includes the effect of the basis difference between the Company's historical cost basis and the basis recorded at the Real Estate Venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from the impairment of investments, purchases of third party interests in existing Real Estate Ventures and upon the transfer of assets that were previously owned by the Company into a Real Estate Venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the Real Estate Venture level.

Investment in Unconsolidated 53

Investment in Unconsolidated Real Estate Ventures - Summary of Results of Operations of Real Estate Ventures with Interests (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule Of Equity Method Investments [Line Items]
Equity in loss of Real Estate Ventures		$ (5,723)	$ (7,254)	$ (5,387)	$ (9,323)
Unconsolidated Real Estate Ventures [Member]
Schedule Of Equity Method Investments [Line Items]
Revenue		56,511	57,710	169,609	157,641
Operating expenses		(27,419)	(27,592)	(77,757)	(81,347)
Provision for impairment			(10,476)		(10,476)
Interest expense, net		(11,670)	(12,102)	(33,771)	(32,019)
Depreciation and amortization		(20,684)	(22,722)	(61,816)	(63,125)
Net loss	[1]	(3,262)	(15,182)	(3,735)	(29,326)
Equity in loss of Real Estate Ventures	[2]	$ (5,723)	$ (7,254)	$ (5,387)	$ (9,323)
[1]	The nine-month period ended September 30, 2016 amount includes $7.1 million of acquisition deal costs related to the formation of the MAP Venture.
[2]	The three- and nine-month periods ended September 30, 2017 include a $4.8 million other than temporary impairment charge related to the BDN-AI Venture that was recorded during the three months ended September 30, 2017.

Investment in Unconsolidated 54

Investment in Unconsolidated Real Estate Ventures - Summary of Results of Operations of Real Estate Ventures with Interests (Parenthetical) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
MAP Venture [Member]
Schedule Of Equity Method Investments [Line Items]
Acquisition deal costs		$ 7.1
BDN - Al Venture [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment other than temporary impairment charge	$ 4.8	$ 4.8

Intangible Assets and Liabili55

Intangible Assets and Liabilities - Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Intangible Assets [Line Items]
Intangible Assets, Total Cost	$ 117,704	$ 160,681
Intangible Assets, Accumulated Amortization	(58,887)	(88,203)
Intangible Assets, net	58,817	72,478
Acquired Lease Intangibles, Net	17,156	18,119
Below market leases [Member]
Intangible Assets [Line Items]
Acquired Lease Intangibles, Gross	32,158	37,579
Acquired Lease Intangibles, Accumulated Amortization	(15,002)	(19,460)
Acquired Lease Intangibles, Net	17,156	18,119
In-place lease value [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	100,519	142,889
Intangible Assets, Accumulated Amortization	(45,765)	(75,696)
Intangible Assets, net	54,754	67,193
Tenant relationship value [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	12,831	13,074
Intangible Assets, Accumulated Amortization	(10,646)	(10,167)
Intangible Assets, net	2,185	2,907
Above market leases acquired [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	4,354	4,718
Intangible Assets, Accumulated Amortization	(2,476)	(2,340)
Intangible Assets, net	$ 1,878	$ 2,378

Intangible Assets and Liabili56

Intangible Assets and Liabilities - Annual Amortization of Intangible Assets, Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets
2017 (three months remaining)	$ 3,443
2,018	12,257
2,019	10,984
2,020	8,904
2,021	6,366
Thereafter	16,863
Intangible Assets, net	58,817	$ 72,478
Liabilities
2017 (three months remaining)	677
2,018	2,512
2,019	2,198
2,020	1,650
2,021	1,062
Thereafter	9,057
Acquired Lease Intangibles, Net	$ 17,156	$ 18,119

Debt Obligations - Consolidated

Debt Obligations - Consolidated Debt Obligations Outstanding (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017		Dec. 31, 2016	Dec. 31, 2015
Consolidated debt obligations
Plus: premiums/(discounts), net		$ (6,371)
Less: deferred financing costs		(6,956)
Line of credit		178,000		$ 0
Total Debt Obligations		1,889,640		2,013,112
Secured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		321,357		325,038
Plus: premiums/(discounts), net		(2,434)		(2,761)
Less: deferred financing costs		(606)		(728)
Total mortgage indebtedness		318,317		321,549
Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		1,581,610		1,703,610
Plus: premiums/(discounts), net		(3,937)		(4,678)
Less: deferred financing costs		(6,350)		(7,369)
Total unsecured indebtedness		1,571,323		1,691,563
Two Logan Square [Member] | Secured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 84,839		86,012
Effective interest rate		3.98%
Debt instrument maturity date		May 1, 2020
One Commerce Square [Member] | Secured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 124,518		127,026
Effective interest rate		3.64%	[1]		3.64%
Debt instrument maturity date		Apr. 5, 2023
Two Commerce Square [Member] | Secured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 112,000		112,000
Effective interest rate	[2]	4.51%
Debt instrument maturity date		Apr. 5, 2023
Revolving Credit Facility [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Line of credit		$ 178,000
Effective interest rate, description		LIBOR + 1.20%
Debt instrument maturity date		May 31, 2019
Revolving Credit Facility [Member] | Unsecured Debt [Member] | LIBOR [Member]
Consolidated debt obligations
Spread on variable rate		1.20%
Seven Year Term Loan - Swapped to fixed [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 250,000		250,000
Effective interest rate		3.72%
Debt instrument maturity date		Oct. 1, 2022
$300.0M 5.70% Guaranteed Notes due 2017 [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross	[3]			300,000
Effective interest rate	[3]	5.68%
Debt instrument maturity date	[3]	May 1, 2017
$325.0M 4.95% Guaranteed Notes due 2018 [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 325,000		325,000
Effective interest rate		5.13%
Debt instrument maturity date		Apr. 15, 2018
$250M 3.95% Guaranteed Notes due 2023 [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 250,000		250,000
Effective interest rate		4.02%
Debt instrument maturity date		Feb. 15, 2023
250.0M 4.10% Guaranteed Notes due 2024 [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 250,000		250,000
Effective interest rate		4.33%
Debt instrument maturity date		Oct. 1, 2024
$250M 4.55% Guaranteed Notes due 2029 [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 250,000		250,000
Effective interest rate		4.60%
Debt instrument maturity date		Oct. 1, 2029
Indenture IA (Preferred Trust I) - Swapped to fixed [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 27,062		27,062
Effective interest rate		2.75%
Debt instrument maturity date		Mar. 30, 2035
Indenture IB (Preferred Trust I) - Swapped to fixed [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 25,774		25,774
Effective interest rate		3.30%
Debt instrument maturity date		Apr. 30, 2035
Indenture II (Preferred Trust II) - Swapped to fixed [Member] | Unsecured Debt [Member]
Consolidated debt obligations
Long-term Debt, Gross		$ 25,774		$ 25,774
Effective interest rate		3.09%
Debt instrument maturity date		Jul. 30, 2035
[1]	This loan was assumed upon acquisition of the related properties on December 19, 2013. On December 29, 2015, the Company refinanced the debt increasing the principal balance to $130.0 million and extended the scheduled maturity date from January 6, 2016 to April 5, 2023.  The effective interest rate as of December 31, 2015 was 3.64%.  A default under this loan will also constitute a default under the loan secured by Two Commerce Square. This loan is also secured by a lien on Two Commerce Square.
[2]	This loan was assumed upon acquisition of the related property on December 19, 2013. The interest rate reflects the market rate at the time of acquisition. A default under this loan will also constitute a default under the loan secured by One Commerce Square. This loan is also secured by a lien on One Commerce Square.
[3]	On May 1, 2017, the entire principal balance of the unsecured 5.70% Guaranteed Notes was repaid upon maturity. Available cash balances and the Credit Facility (as defined below) were used to fund the repayment of the unsecured notes.

Debt Obligations - Consolidat58

Debt Obligations - Consolidated Debt Obligations Outstanding (Parenthetical) (Details) - USD ($) $ in Millions		Dec. 29, 2015	Sep. 30, 2017		May 01, 2017	Dec. 31, 2015
One Commerce Square [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt instrument increase in principal		$ 130
Debt instrument maturity date			Apr. 5, 2023
Effective interest rate			3.64%	[1]		3.64%
$300.0M 5.70% Guaranteed Notes due 2017 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt instrument maturity date	[2]		May 1, 2017
Effective interest rate	[2]		5.68%
Debt Instrument Interest Rate Stated Percentage					5.70%
[1]	This loan was assumed upon acquisition of the related properties on December 19, 2013. On December 29, 2015, the Company refinanced the debt increasing the principal balance to $130.0 million and extended the scheduled maturity date from January 6, 2016 to April 5, 2023.  The effective interest rate as of December 31, 2015 was 3.64%.  A default under this loan will also constitute a default under the loan secured by Two Commerce Square. This loan is also secured by a lien on Two Commerce Square.
[2]	On May 1, 2017, the entire principal balance of the unsecured 5.70% Guaranteed Notes was repaid upon maturity. Available cash balances and the Credit Facility (as defined below) were used to fund the repayment of the unsecured notes.

Debt Obligations (Textual) (Det

Debt Obligations (Textual) (Details) - USD ($)	May 15, 2015	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Line of credit		$ 178,000,000	$ 0
Revolving Credit Facility [Member] | New Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate		2.34%
Debt term	4 years
Maximum borrowing capacity		$ 600,000,000
Line of credit		$ 178,000,000
Variable interest rate		1.20%
Variable interest rate, LIBOR period description		LIBOR plus 1.20%.
Letters of credit outstanding amount		$ 13,500,000
Proceeds from line of credit		0
Unused borrowing capacity		$ 408,500,000
Effective interest rate on credit facility		2.43%
Secured Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate		4.03%	4.03%

Debt Obligations - Aggregate Sc

Debt Obligations - Aggregate Scheduled Principal Payments of Debt Obligation, Excluding Amortization of Discounts and Premiums (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
2017 (three months remaining)	$ 1,250
2,018	331,601
2,019	185,360
2,020	86,978
2,021	6,099
Thereafter	1,291,679
Total principal payments	1,902,967
Plus: premiums/(discounts), net	(6,371)
Net deferred financing costs	(6,956)
Total Debt Obligations	$ 1,889,640	$ 2,013,112

Fair Value of Financial Instr61

Fair Value of Financial Instruments - Financial Instruments for which Estimates of Fair Value Differ from Carrying Amounts (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Mortgage notes payable, net		$ 318,317	$ 321,549
Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Note receivable	[1],[2]	3,384	3,380
Carrying Amount [Member] | Unsecured Notes Payable [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured notes payable	[1]	1,066,366	1,364,854
Carrying Amount [Member] | Variable Rate Debt [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Variable rate debt	[1]	504,957	326,709
Carrying Amount [Member] | Mortgages Notes Payable [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Mortgage notes payable, net	[1]	318,317	321,549
Fair Value [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Note receivable, fair value	[2]	3,655	3,717
Fair Value [Member] | Unsecured Notes Payable [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt instrument, fair value		1,087,263	1,372,758
Fair Value [Member] | Variable Rate Debt [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt instrument, fair value		486,653	307,510
Fair Value [Member] | Mortgages Notes Payable [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Debt instrument, fair value		$ 305,657	$ 328,853
[1]	In April 2015, the FASB issued guidance requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct reduction from the carrying amount of the corresponding debt liability, consistent with debt discounts. As a result, the carrying amounts presented in the table above are net of deferred financing costs of $4.7 million and $5.5 million for unsecured notes payable, $1.7 million and $1.9 million for variable rate debt and $0.6 million and $0.7 million for mortgage notes payable as of September 30, 2017 and December 31, 2016, respectively.
[2]	The inputs to originate the note receivable are unobservable and, as a result, are categorized as Level 3. The Company determined fair value by calculating the present value of the cash payments to be received through the maturity date of the loan. See Note 2, “Summary of Significant Accounting Policies,” to the Company’s 2016 Annual Report on Form 10-K for the year ended December 31, 2016 for further information regarding the note origination.

Fair Value of Financial Instr62

Fair Value of Financial Instruments - Financial Instruments for which Estimates of Fair Value Differ from Carrying Amounts (Parenthetical) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Deferred financing costs, net	$ 6,956
Unsecured Notes Payable [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Deferred financing costs, net	6,350	$ 7,369
Unsecured Notes Payable [Member] | Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Deferred financing costs, net	4,700	5,500
Variable Rate Debt [Member] | Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Deferred financing costs, net	1,700	1,900
Mortgages Notes Payable [Member] | Carrying Amount [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Deferred financing costs, net	$ 600	$ 700

Fair Value of Financial Instr63

Fair Value of Financial Instruments (Textual) (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Variable rate and mortgage debt [Member]
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Discount Rates	4.143%	4.353%

Limited Partners' Non-Control64

Limited Partners' Non-Controlling Interests in the Parent Company (Textual) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Noncontrolling Interest [Abstract]
Aggregate amount related to non-controlling interests classified within equity	$ 14.6	$ 14.9
Settlement value of non controlling interest in operating partnership	$ 25.9	$ 24.4

Fair Value of Derivative Fina65

Fair Value of Derivative Financial Instruments - Terms and Fair Values of Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivatives Fair Value [Line Items]
Notional Amount	$ 328,610	$ 328,610
3.718% Interest Rate Swap Maturing October 8, 2022 [Member] | Cash Flow Hedging [Member]
Derivatives Fair Value [Line Items]
Derivative, Fixed Interest Rate	3.718%
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ (3,185)
Derivative Asset, Notional Amount	250,000	250,000
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		3,733
3.300% Interest Rate Swap Maturing January 30, 2021 [Member] | Cash Flow Hedging [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Notional Amount	$ 25,774	25,774
Derivative, Fixed Interest Rate	3.30%
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ (209)	(300)
3.090% Interest Rate Swap Maturing October 30, 2019 [Member] | Cash Flow Hedging [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Notional Amount	$ 25,774	25,774
Derivative, Fixed Interest Rate	3.09%
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ (88)	(214)
2.750% Interest Rate Swap Maturing September 30, 2017 [Member] | Cash Flow Hedging [Member]
Derivatives Fair Value [Line Items]
Derivative Liability, Notional Amount	$ 27,062	27,062
Derivative, Fixed Interest Rate	2.75%
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		$ (83)

Beneficiaries Equity of the P66

Beneficiaries Equity of the Parent Company - Number of Shares and Net Income Used to Calculate Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator
Income from continuing operations, Basic	$ 19,046	$ 7,884	$ 48,015	$ 52,871
Net income from continuing operations attributable to non-controlling interests, Basic	(170)	(58)	(384)	(425)
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(73)	(79)	(245)	(263)
Distribution to preferred shareholders	0	(1,725)	(2,032)	(5,175)
Preferred share redemption charge	0	0	(3,181)	0
Net income attributable to Common Shareholders of Brandywine Realty Trust	18,803	6,022	42,173	47,008
Net income from continuing operations attributable to non-controlling interests, Diluted	(170)	(58)	(384)	(425)
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(73)	(79)	(245)	(263)
Net income attributable to common shareholders, Diluted	$ 18,803	$ 6,022	$ 42,173	$ 47,008
Denominator
Basic weighted average shares outstanding (in shares)	175,433,657	175,127,110	175,315,581	174,976,998
Contingent securities/Share based compensation (in shares)	1,401,365	1,237,505	1,283,751	1,032,824
Diluted weighted average shares outstanding (in shares)	176,835,022	176,364,615	176,599,332	176,009,822
Earnings per Common Share:
Net income attributable to common shareholders, Basic (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Net income attributable to common shareholders, Diluted (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27

Beneficiaries Equity of the P67

Beneficiaries Equity of the Parent Company (Textual) (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 12, 2017	Apr. 11, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Class of Stock [Line Items]
Dividends, Common Stock	$ 28,400
Preferred share redemption charge			$ 0	$ 0	$ 3,181	$ 0
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Class of Stock [Line Items]
Dividends, Common Stock	$ 28,400
Preferred share redemption charge			$ 0	$ 0	$ 3,181	$ 0
BRANDYWINE OPERATING PARTNERSHIP, L.P. | Series E Preferred Stock [Member]
Class of Stock [Line Items]
Redemption outstanding shares		4,000,000
Redemption price per share		$ 25.51
Accrued dividends paid in cash		$ 2,000
Preferred share redemption charge		$ 3,200
Dividend Declared [Member]
Class of Stock [Line Items]
Dividends Payable, Amount Per Share	$ 0.16
Dividend Declared [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Class of Stock [Line Items]
Dividends Payable, Amount Per Share	$ 0.16
Redeemable Common Limited Partnership Units [Member]
Class of Stock [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share					1,479,799	1,479,799

Partners Equity of the Operat68

Partners Equity of the Operating Partnership - Number of Units and Net Income Used to Calculate Basic and Diluted Earnings Per Common Partnership Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator
Income from continuing operations, Basic	$ 19,046	$ 7,884	$ 48,015	$ 52,871
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(73)	(79)	(245)	(263)
Distribution to preferred shareholders	0	(1,725)	(2,032)	(5,175)
Preferred share redemption charge	0	0	(3,181)	0
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	$ (73)	$ (79)	$ (245)	$ (263)
Denominator
Basic weighted average shares outstanding (in shares)	175,433,657	175,127,110	175,315,581	174,976,998
Contingent securities/Share based compensation (in shares)	1,401,365	1,237,505	1,283,751	1,032,824
Diluted weighted average shares outstanding (in shares)	176,835,022	176,364,615	176,599,332	176,009,822
Earnings per Common Partnership Unit
Net income attributable to common unitholders, Basic (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Net income attributable to common unitholders, Diluted (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Numerator
Income from continuing operations, Basic	$ 19,046	$ 7,884	$ 48,015	$ 52,871
Nonforfeitable dividends allocated to unvested restricted shareholders, Basic	(73)	(79)	(245)	(263)
Distribution to preferred shareholders	0	(1,725)	(2,032)	(5,175)
Preferred share redemption charge	0	0	(3,181)	0
Net income attributable to non-controlling interests	(12)	(6)	(26)	(12)
Net income attributable to common unitholders, Basic	18,961	6,074	42,531	47,421
Nonforfeitable dividends allocated to unvested restricted shareholders, Diluted	(73)	(79)	(245)	(263)
Net income attributable to common unitholders, Diluted	$ 18,961	$ 6,074	$ 42,531	$ 47,421
Denominator
Basic weighted average shares outstanding (in shares)	176,913,456	176,606,909	176,795,380	176,491,311
Contingent securities/Share based compensation (in shares)	1,401,365	1,237,505	1,283,751	1,032,824
Diluted weighted average shares outstanding (in shares)	178,314,821	177,844,414	178,079,131	177,524,135
Earnings per Common Partnership Unit
Net income attributable to common unitholders, Basic (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27
Net income attributable to common unitholders, Diluted (USD per share)	$ 0.11	$ 0.03	$ 0.24	$ 0.27

Partners Equity of the Operat69

Partners Equity of the Operating Partnership (Textual) (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 12, 2017	Apr. 11, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Common Partnership Unit [Line Items]
Dividends, Common Stock	$ 28,400
Preferred share redemption charge			$ 0	$ 0	$ 3,181	$ 0
Dividend Declared [Member]
Earnings Per Common Partnership Unit [Line Items]
Dividends Payable, Amount Per Share	$ 0.16
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Earnings Per Common Partnership Unit [Line Items]
Dividends, Common Stock	$ 28,400
Preferred share redemption charge			$ 0	$ 0	$ 3,181	$ 0
BRANDYWINE OPERATING PARTNERSHIP, L.P. | Series E Preferred Stock [Member]
Earnings Per Common Partnership Unit [Line Items]
Redemption outstanding shares		4,000,000
Redemption price per share		$ 25.51
Accrued dividends paid in cash		$ 2,000
Preferred share redemption charge		$ 3,200
BRANDYWINE OPERATING PARTNERSHIP, L.P. | Dividend Declared [Member]
Earnings Per Common Partnership Unit [Line Items]
Dividends Payable, Amount Per Share	$ 0.16

Segment Information (Textual) (

Segment Information (Textual) (Details)	Feb. 02, 2017property	Sep. 30, 2017propertysegment
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment		5
Office Properties [Member]
Segment Reporting Information [Line Items]
Number of Properties Sold		12
Office Properties [Member] | 1200 & 1220 Concord Avenue (Concord Airport Plaza) [Member]
Segment Reporting Information [Line Items]
Number of Properties Sold	2	2

Segment Information - Real Esta

Segment Information - Real Estate Investments, at Cost of Company's Reportable Segments (Details) - USD ($) $ in Thousands		Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Operating properties		$ 3,769,067	$ 3,586,295
Assets held for sale - real estate investments	[1],[2]	47,291	73,591
Operating properties		3,816,358	3,659,886
Construction-in-progress		127,141	297,462
Land held for development		120,696	150,970
Philadelphia CBD [Member]
Segment Reporting Information [Line Items]
Operating properties		1,591,828	1,320,974
Pennsylvania Suburbs [Member]
Segment Reporting Information [Line Items]
Operating properties	[3]	966,128	1,005,446
Metropolitan DC [Member]
Segment Reporting Information [Line Items]
Operating properties		976,286	975,987
Austin, Texas [Member]
Segment Reporting Information [Line Items]
Operating properties		146,859	146,794
Other [Member]
Segment Reporting Information [Line Items]
Operating properties		$ 87,966	$ 137,094
[1]	Real estate investments related to assets held for sale above represents gross real estate assets and does not include accumulated depreciation, land held for development or other assets on the balance sheet of the property held for sale. See Note 3, “Real Estate Investments,” for further information.
[2]	Real estate investments related to assets held for sale above represents gross real estate assets and does not include accumulated depreciation, land held for development or other assets on the balance sheet of the property held for sale. See “Held for Sale” below in this Note 3.
[3]	As of September 30, 2017, the Company categorized six office properties in its Pennsylvania Suburbs segment as held for sale in accordance with applicable accounting standards for long lived assets. See Note 3, “Real Estate Investments,” for further information.

Segment Information - Real Es72

Segment Information - Real Estate Investments, at Cost of Company's Reportable Segments (Parenthetical) (Details)	Sep. 30, 2017property
Segment Reporting Information [Line Items]
Number of Properties	97
Assets Held-for-sale [Member]
Segment Reporting Information [Line Items]
Number of Properties	6
Office Properties [Member]
Segment Reporting Information [Line Items]
Number of Properties	82
Office Properties [Member] | Pennsylvania Suburbs [Member] | Assets Held-for-sale [Member]
Segment Reporting Information [Line Items]
Number of Properties	6

Segment Information - Net Opera

Segment Information - Net Operating Income of Company's Reportable Segments (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Total revenue		$ 128,438	$ 129,694	$ 387,149	$ 393,377
Operating expenses	[1]	(50,701)	(51,317)	(152,400)	(156,313)
Net operating income (loss)		77,737	78,377	234,749	237,064
Operating Segments [Member] | Philadelphia CBD [Member]
Segment Reporting Information [Line Items]
Total revenue		56,452	50,744	165,352	148,496
Operating expenses	[1]	(22,010)	(19,071)	(64,311)	(58,102)
Net operating income (loss)		34,442	31,673	101,041	90,394
Operating Segments [Member] | Pennsylvania Suburbs [Member]
Segment Reporting Information [Line Items]
Total revenue		34,861	35,763	105,673	107,971
Operating expenses	[1]	(11,846)	(11,247)	(35,670)	(36,982)
Net operating income (loss)		23,015	24,516	70,003	70,989
Operating Segments [Member] | Metropolitan DC [Member]
Segment Reporting Information [Line Items]
Total revenue		23,079	24,251	69,190	76,881
Operating expenses	[1]	(8,500)	(9,900)	(26,347)	(29,567)
Net operating income (loss)		14,579	14,351	42,843	47,314
Operating Segments [Member] | Austin, Texas [Member]
Segment Reporting Information [Line Items]
Total revenue		7,886	8,726	25,772	25,123
Operating expenses	[1]	(3,929)	(3,523)	(11,634)	(9,689)
Net operating income (loss)		3,957	5,203	14,138	15,434
Operating Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Total revenue		3,752	8,526	14,274	30,328
Operating expenses	[1]	(2,647)	(4,837)	(9,083)	(17,513)
Net operating income (loss)		1,105	3,689	5,191	12,815
Corporate [Member]
Segment Reporting Information [Line Items]
Total revenue		2,408	1,684	6,888	4,578
Operating expenses	[1]	(1,769)	(2,739)	(5,355)	(4,460)
Net operating income (loss)		$ 639	$ (1,055)	$ 1,533	$ 118
[1]	Includes property operating expense, real estate taxes and third party management expense.

Segment Information - Unconsoli

Segment Information - Unconsolidated Real Estate Ventures of Company's Reportable Segments (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity		$ 236,313		$ 236,313		$ 281,331
Equity in income (loss) of real estate ventures		(5,723)	$ (7,254)	(5,387)	$ (9,323)
Philadelphia CBD [Member]
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity		42,298		42,298		48,691
Equity in income (loss) of real estate ventures		134	(453)	113	(473)
Pennsylvania Suburbs [Member]
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity		3,320		3,320		15,421
Equity in income (loss) of real estate ventures		24	(170)	448	410
Metropolitan DC [Member]
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity	[1]	119,550		119,550		141,786
Equity in income (loss) of real estate ventures	[1]	(5,264)	(5,287)	(4,872)	(6,068)
Austin, Texas [Member]
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity		52,940		52,940		52,886
Equity in income (loss) of real estate ventures		(15)	(561)	1,266	(1,299)
MAP Venture [Member]
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity	[2]	16,283		16,283		20,893
Equity in income (loss) of real estate ventures	[2]	(706)	(1,010)	(2,610)	(2,608)
Other [Member]
Segment Reporting Information [Line Items]
Investment in real estate ventures, at equity		1,922		1,922		$ 1,654
Equity in income (loss) of real estate ventures		$ 104	$ 227	$ 268	$ 715
[1]	The three- and nine-month periods ended September 30, 2017 include a $4.8 million other than temporary impairment charge related to the BDN - AI Venture that was recorded during the three months ended September 30, 2017.
[2]	The MAP Venture represents a joint venture formed between the Company and MAP Ground Lease Holdings LLC, an affiliate of Och-Ziff Capital Management Group, LLC, on February 4, 2016. The MAP Venture’s business operations, including properties in Richmond, Virginia; Metropolitan Washington, D.C.; New Jersey/Delaware and Pennsylvania Suburbs, are centrally managed with the results reported to management of the Company on a consolidated basis. As a result, the investment in the MAP Venture is separately presented. All other unconsolidated real estate ventures are managed consistently with the Company’s regional segments.

Segment Information - Unconso75

Segment Information - Unconsolidated Real Estate Ventures of Company's Reportable Segments (Parenthetical) (Details) - BDN - Al Venture [Member] - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Segment Reporting Information [Line Items]
Equity method investment other-than-temporary impairment charge	$ 4.8	$ 4.8
Metropolitan DC [Member]
Segment Reporting Information [Line Items]
Equity method investment other-than-temporary impairment charge	$ 4.8	$ 4.8

Segment Information - Reconcili

Segment Information - Reconciliation of Consolidated Net Income to Consolidated NOI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting [Abstract]
Net income	$ 19,046	$ 7,884	$ 48,015	$ 52,871
Plus:
Interest expense	19,732	20,814	61,473	64,334
Interest expense - amortization of deferred financing costs	577	645	1,807	2,063
Interest expense - financing obligation	0	156	0	679
Depreciation and amortization	42,429	46,956	132,584	142,736
General and administrative expenses	5,813	5,515	21,797	20,711
Equity in loss of Real Estate Ventures	5,723	7,254	5,387	9,323
Provision for impairment	0	0	3,057	13,069
Loss on early extinguishment of debt	0	0	0	66,590
Less:
Interest income	79	291	635	970
Income tax benefit	793	0	1,032	0
Net gain (loss) on disposition of real estate	0	(104)	8,411	114,625
Net gain on sale of undepreciated real estate	953	188	953	188
Net gain on Real Estate Venture transactions	13,758	10,472	28,340	19,529
Consolidated net operating income	$ 77,737	$ 78,377	$ 234,749	$ 237,064

Commitments and Contingencies77

Commitments and Contingencies (Textual) (Details)	Dec. 03, 2015ft²Floor	Apr. 02, 2015USD ($)	Sep. 30, 2017USD ($)a	Sep. 30, 2017USD ($)a	Jul. 01, 2016aParcel
Subaru Corporate Headquarters Project [Member]
Property Subject to or Available for Operating Lease [Line Items]
Number of floors | Floor	5
Area of office property | ft²	250,000
Residual profit recognized			$ 2,100,000	$ 2,100,000
Residual profit earned			800,000	1,600,000
NTE Amount			79,400,000	79,400,000
Project costs funded			57,200,000	57,200,000
Subaru Build-to-Service Center Project [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease terms	18 years
Rentable Square Feet | ft²	83,000
Purchase option of lease from inception period	5 years
Estimated project costs			44,300,000	44,300,000
Subaru Build-to-Service Center Project [Member] | Other Assets [Member]
Property Subject to or Available for Operating Lease [Line Items]
Project costs funded			12,400,000	12,400,000
1919 Venture [Member]
Property Subject to or Available for Operating Lease [Line Items]
Guarantees, maximum exposure amount			88,900,000	88,900,000
Unconsolidated Real Estate Ventures [Member]
Property Subject to or Available for Operating Lease [Line Items]
Real estate ventures aggregate indebtedness to third parties			915,000,000	915,000,000
evo at Cira Centre South Venture [Member]
Property Subject to or Available for Operating Lease [Line Items]
Guarantees, maximum exposure amount			55,400,000	55,400,000
PJP VII [Member]
Property Subject to or Available for Operating Lease [Line Items]
Guarantees, maximum exposure amount			400,000	400,000
618 Market Street [Member]
Property Subject to or Available for Operating Lease [Line Items]
Contingent consideration, liability		$ 2,000,000	$ 1,800,000	$ 1,800,000
Fair value of contingent consideration		1,600,000
Interest expense		$ 2,000,000
Garza Land Acquisition [Member]
Property Subject to or Available for Operating Lease [Line Items]
Acreage of land | a					34.6
Number of Parcels | Parcel					2
Garza Land Acquisition [Member] | Parcel One [Member]
Property Subject to or Available for Operating Lease [Line Items]
Area of land sold | a			8.4	8.4
Garza Land Acquisition [Member] | Parcel Two [Member]
Property Subject to or Available for Operating Lease [Line Items]
Area of land sold | a			1.7	1.7
Garza Land Acquisition [Member] | A1000 Atrium Way And Libertyview
Property Subject to or Available for Operating Lease [Line Items]
Infrastructure improvements to land, estimated cost			$ 13,200,000	$ 13,200,000
Put Agreement [Member]
Property Subject to or Available for Operating Lease [Line Items]
Purchase price			35,000,000	$ 35,000,000
Minimum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease terms				12 years
Maximum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Lease terms				72 years
Mortgage Lenders [Member]
Property Subject to or Available for Operating Lease [Line Items]
Associated letter of credit			$ 10,000,000	$ 10,000,000

Commitments and Contingencies -

Commitments and Contingencies - Minimum Future Rental Payments on Non-cancelable Leases (Details) $ in Thousands	Sep. 30, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
2017 (three months remaining)	$ 303
2,018	1,211
2,019	1,211
2,020	1,211
2,021	1,211
Thereafter	57,527
Total	$ 62,674

Income Taxes - (Textual) (Detai

Income Taxes - (Textual) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Minimum percentage of gross income derived from qualifying sources to qualify as REIT	95.00%
Minimum percentage of taxable income distribution to stockholders to qualify as REIT	90.00%
Subsequent period during which entity would be disqualified as a REIT if during any tax year entity fails to qualify as a REIT	4 years
Deferred tax asset recognized	$ 1,000,000		$ 0
Accruals for tax uncertainties	$ 0	$ 0

Subsequent Events (Textual) (De

Subsequent Events (Textual) (Details) - Subsequent Event [Member]	Oct. 18, 2017USD ($)ft²property	Oct. 16, 2017USD ($)ft²	Oct. 02, 2017USD ($)ft²	Oct. 17, 2017USD ($)
DRA Austin Venture [Member]
Subsequent Event [Line Items]
Rentable Square Feet | ft²	1,164,496
Ownership percentage	50.00%
Number of Properties Sold | property	5
Sales Price	$ 333,300,000
Real estate properties encumbered, mortgage debt amount				$ 151,000,000
Cash proceeds after the payment of share of the debt, closing costs and prorations	86,400,000
Estimated gain on real estate venture transactions and equity in income of real estate ventures	$ 52,000,000
One Drexel Plaza and Drexel Square [Member]
Subsequent Event [Line Items]
Rentable Square Feet | ft²		282,709
Gross purchase value of assets		$ 35,000,000
Capitalized transaction costs		$ 2,700,000
Property improvement period		24 months
One Drexel Plaza and Drexel Square [Member] | Minimum [Member]
Subsequent Event [Line Items]
Property improvement obligation		$ 8,000,000
Four Points Building 3 [Member]
Subsequent Event [Line Items]
Net Rentable Square Feet | ft²			165,000
Percentage of property preleased by single tenant			100.00%
Lease agreement term			10 years
Estimated cost			$ 48,200,000
Estimated cost for existing land basis			$ 2,100,000