Brandywine Operating Partnership 10-Q 25 Jul 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document	6 Months Ended
	Jun. 30, 2014	Jul. 23, 2014
Document Information [Line Items]	'	'
Entity Registrant Name	'BRANDYWINE REALTY TRUST	'
Entity Central Index Key	'0000790816	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	157,090,635
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'
BRANDYWINE OPERATING PARTNERSHIP, L.P.	'	'
Document Information [Line Items]	'	'
Entity Registrant Name	'BRANDYWINE OPERATING PARTNERSHIP, L.P.	'
Entity Central Index Key	'0001060386	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Non-accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Amendment Flag	'false	'
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Real estate investments:	'	'
Operating properties	$4,689,892	$4,669,289
Accumulated depreciation	-1,045,016	-983,808
Operating real estate investments, net	3,644,876	3,685,481
Construction-in-progress	92,713	74,174
Land inventory	90,266	93,351
Total real estate investments, net	3,827,855	3,853,006
Cash and cash equivalents	234,836	263,207
Accounts receivable, net	21,622	17,389
Accrued rent receivable, net	131,280	126,295
Investment in real estate ventures, at equity	186,042	180,512
Deferred costs, net	123,592	122,954
Intangible assets, net	112,140	132,329
Other assets	66,806	69,403
Total assets	4,704,173	4,765,095
LIABILITIES AND BENEFICIARIES’ EQUITY	'	'
Mortgage notes payable	662,478	670,151
Unsecured term loans	450,000	450,000
Unsecured senior notes, net of discounts	1,475,772	1,475,230
Accounts payable and accrued expenses	83,114	83,693
Distributions payable	25,588	25,584
Deferred income, gains and rent	70,519	71,635
Acquired lease intangibles, net	29,116	34,444
Other liabilities	37,144	32,923
Total liabilities	2,833,731	2,843,660
Commitments and contingencies (Note 16)	'	'
Equity:	'	'
6.90% Series E Preferred Shares/Units, $0.01 par value; issued and outstanding- 4,000,000 in 2014 and 2013	40	40
Common Shares of Brandywine Realty Trust’s beneficial interest, $0.01 par value; shares authorized 400,000,000; 157,090,983 and 156,731,993 issued and outstanding in 2014 and 2013, respectively	1,571	1,566
Additional paid-in capital	2,975,070	2,971,596
Deferred compensation payable in common shares	6,303	5,407
Common shares in grantor trust, 387,087 in 2014 and 312,280 in 2013	-6,303	-5,407
Cumulative earnings	522,520	522,528
Accumulated other comprehensive loss	-6,105	-2,995
Cumulative distributions	1,643,241	1,592,515
Total equity, excluding non-controlling interest	1,849,855	1,900,220
Non-controlling interests	20,587	21,215
Total beneficiaries' equity	1,870,442	1,921,435
Total liabilities and beneficiaries' equity	4,704,173	4,765,095
BRANDYWINE OPERATING PARTNERSHIP, L.P.	'	'
Real estate investments:	'	'
Operating properties	4,689,892	4,669,289
Accumulated depreciation	-1,045,016	-983,808
Operating real estate investments, net	3,644,876	3,685,481
Construction-in-progress	92,713	74,174
Land inventory	90,266	93,351
Total real estate investments, net	3,827,855	3,853,006
Cash and cash equivalents	234,836	263,207
Accounts receivable, net	21,622	17,389
Accrued rent receivable, net	131,280	126,295
Investment in real estate ventures, at equity	186,042	180,512
Deferred costs, net	123,592	122,954
Intangible assets, net	112,140	132,329
Other assets	66,806	69,403
Total assets	4,704,173	4,765,095
LIABILITIES AND BENEFICIARIES’ EQUITY	'	'
Mortgage notes payable	662,478	670,151
Unsecured term loans	450,000	450,000
Unsecured senior notes, net of discounts	1,475,772	1,475,230
Accounts payable and accrued expenses	83,114	83,693
Distributions payable	25,588	25,584
Deferred income, gains and rent	70,519	71,635
Acquired lease intangibles, net	29,116	34,444
Other liabilities	37,144	32,923
Total liabilities	2,833,731	2,843,660
Commitments and contingencies (Note 16)	'	'
Redeemable limited partnership units at redemption value;	'	'
Redeemable limited partnership units at redemption value; 1,763,739 issued and outstanding in 2014 and 2013, respectively	27,211	26,486
Equity:	'	'
6.90% Series E Preferred Shares/Units, $0.01 par value; issued and outstanding- 4,000,000 in 2014 and 2013	96,850	96,850
General Partnership Capital, 157,090,983 and 156,731,993 units issued and outstanding in 2014 and 2013, respectively	1,751,968	1,800,530
Accumulated other comprehensive loss	-6,522	-3,377
Total equity, excluding non-controlling interest	1,842,296	1,894,003
Non-controlling interests	935	946
Total beneficiaries' equity	1,843,231	1,894,949
Total liabilities and beneficiaries' equity	$4,704,173	$4,765,095

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parentheticals) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Dividend Rate, Percentage	6.90%	6.90%
Preferred Stock, Shares Issued	4,000,000	4,000,000
Preferred Stock, Shares Outstanding	4,000,000	4,000,000
Preferred Stock, Par or Stated Value Per Share	$0.01	$0.01
Common Stock, Par or Stated Value Per Share	$0.01	$0.01
Common Stock, Shares Authorized	400,000,000	200,000,000
Common Stock, Shares, Issued	157,090,983	156,731,993
Common Stock, Shares, Outstanding	157,090,983	156,731,993
Common shares in grantor trust	387,088	312,280
BRANDYWINE OPERATING PARTNERSHIP, L.P.	'	'
Preferred Stock, Dividend Rate, Percentage	6.90%	6.90%
Preferred Stock, Shares Issued	4,000,000	4,000,000
Preferred Stock, Shares Outstanding	4,000,000	4,000,000
Redeemable Limited Partnership Units Issued	1,763,739	1,763,739
Redeemable Limited Partnership Units Outstanding	1,763,739	1,763,739
General Partners' Capital Account, Units Issued	157,090,983	156,731,993
General Partners' Capital Account, Units Outstanding	157,090,983	156,731,993

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenue:	'	'	'	'
Rents	$121,622	$116,064	$243,293	$230,672
Tenant reimbursements	20,502	19,560	43,962	39,901
Termination fees	3,349	410	5,552	906
Third party management fees, labor reimbursement and leasing	4,187	3,153	8,337	6,389
Other	840	1,457	1,470	2,330
Total revenue	150,500	140,644	302,614	280,198
Expenses:	'	'	'	'
Property operating expenses	43,136	39,433	89,937	78,782
Real estate taxes	12,841	14,177	26,298	28,472
Third party management expenses	1,730	1,363	3,446	2,788
Depreciation and amortization	52,587	49,241	105,157	98,717
General and administrative expenses	6,005	7,336	14,186	13,887
Total operating expenses	116,299	111,550	239,024	222,646
Operating Income	34,201	29,094	63,590	57,552
Other income (expense):	'	'	'	'
Interest income	385	122	770	180
Interest expense	-31,512	-30,437	-63,356	-61,351
Amortization of deferred financing costs	-1,197	-1,183	-2,386	-2,344
Interest expense — financing obligation	-316	-211	-588	-429
Equity in income (loss) of real estate ventures	-489	1,508	-247	3,043
Gain (loss) on sale of undepreciated real estate	-3	0	1,184	0
Gain from remeasurement of investment in real estate ventures	458	7,847	458	7,847
Gain (loss) on real estate venture transactions	-282	3,683	-417	3,683
Loss on early extinguishment of debt	0	-1,113	0	-1,116
Income (loss) from continuing operations	1,245	9,310	-992	7,065
Discontinued operations:	'	'	'	'
Income from discontinued operations	26	129	18	989
Net gain (loss) on disposition of discontinued operations	903	-2,259	903	3,045
Total discontinued operations	929	-2,130	921	4,034
Net income (loss)	2,174	7,180	-71	11,099
Discontinued operations attributable to non-controlling interests, Basic	-10	25	-10	-53
Net income attributable to non-controlling interest — partners' share of consolidated real estate ventures	24	0	12	0
Net (income) loss attributable to non-controlling interests — LP units	5	-87	49	-37
Net (income) loss attributable to non-controlling interests	19	-62	51	-90
Net income (loss) attributable to Brandywine Realty Trust	2,193	7,118	-20	11,009
Distribution to Preferred Shares	-1,725	-1,725	-3,450	-3,450
Nonforfeitable dividends allocated to unvested restricted shareholders	-83	-85	-186	-193
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	385	5,308	-3,656	7,366
Basic income (loss) per Common Share:	'	'	'	'
Continuing operations	$0	$0.05	($0.03)	$0.02
Discontinued operations	$0	($0.02)	$0.01	$0.03
Net income (loss) attributable to common shareholders/unitholders, Basic	$0	$0.03	($0.02)	$0.05
Diluted income (loss) per Common Share:	'	'	'	'
Continuing operations	$0	$0.05	($0.03)	$0.02
Discontinued operations	$0	($0.02)	$0.01	$0.03
Net income attributable to common shareholders/unitholders, Diluted	$0	$0.03	($0.02)	$0.05
Weighted Average Number of Shares Outstanding, Basic	157,037,348	155,347,384	156,916,356	149,508,957
Weighted Average Number of Shares Outstanding, Diluted	157,037,348	156,691,201	156,916,356	150,666,245
Net income (loss) attributable to Brandywine Realty Trust	'	'	'	'
Total continuing operations	1,274	9,223	-931	7,028
Total discontinued operations	919	-2,105	911	3,981
Net income (loss)	2,174	7,180	-71	11,099
Net income (Loss) attributable to Brandywine Realty Trust	2,193	7,118	-20	11,009
BRANDYWINE OPERATING PARTNERSHIP, L.P.	'	'	'	'
Revenue:	'	'	'	'
Rents	121,622	116,064	243,293	230,672
Tenant reimbursements	20,502	19,560	43,962	39,901
Termination fees	3,349	410	5,552	906
Third party management fees, labor reimbursement and leasing	4,187	3,153	8,337	6,389
Other	840	1,457	1,470	2,330
Total revenue	150,500	140,644	302,614	280,198
Expenses:	'	'	'	'
Property operating expenses	43,136	39,433	89,937	78,782
Real estate taxes	12,841	14,177	26,298	28,472
Third party management expenses	1,730	1,363	3,446	2,788
Depreciation and amortization	52,587	49,241	105,157	98,717
General and administrative expenses	6,005	7,336	14,186	13,887
Total operating expenses	116,299	111,550	239,024	222,646
Operating Income	34,201	29,094	63,590	57,552
Other income (expense):	'	'	'	'
Interest income	385	122	770	180
Interest expense	-31,512	-30,437	-63,356	-61,351
Amortization of deferred financing costs	-1,197	-1,183	-2,386	-2,344
Interest expense — financing obligation	-316	-211	-588	-429
Equity in income (loss) of real estate ventures	-489	1,508	-247	3,043
Gain (loss) on sale of undepreciated real estate	-3	0	1,184	0
Gain from remeasurement of investment in real estate ventures	458	7,847	458	7,847
Gain (loss) on real estate venture transactions	-282	3,683	-417	3,683
Loss on early extinguishment of debt	0	-1,113	0	-1,116
Income (loss) from continuing operations	1,245	9,310	-992	7,065
Discontinued operations:	'	'	'	'
Income from discontinued operations	26	129	18	989
Net gain (loss) on disposition of discontinued operations	903	-2,259	903	3,045
Total discontinued operations	929	-2,130	921	4,034
Net income (loss)	2,174	7,180	-71	11,099
Net income attributable to non-controlling interest — partners' share of consolidated real estate ventures	24	0	12	0
Net income (loss) attributable to Brandywine Realty Trust	2,198	7,180	-59	11,099
Distribution to Preferred Shares	-1,725	-1,725	-3,450	-3,450
Nonforfeitable dividends allocated to unvested restricted shareholders	-83	-85	-186	-193
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	390	5,370	-3,695	7,456
Basic income (loss) per Common Share:	'	'	'	'
Continuing operations	$0	$0.05	($0.03)	$0.02
Discontinued operations	$0	($0.02)	$0.01	$0.03
Net income (loss) attributable to common shareholders/unitholders, Basic	$0	$0.03	($0.02)	$0.05
Diluted income (loss) per Common Share:	'	'	'	'
Continuing operations	$0	$0.05	($0.03)	$0.02
Discontinued operations	$0	($0.02)	$0.01	$0.03
Net income attributable to common shareholders/unitholders, Diluted	$0	$0.03	($0.02)	$0.05
Weighted Average Number of Shares Outstanding, Basic	158,801,087	157,131,697	158,680,095	151,323,813
Weighted Average Number of Shares Outstanding, Diluted	158,801,087	158,475,514	158,680,095	152,481,101
Net income (loss) attributable to Brandywine Realty Trust	'	'	'	'
Total continuing operations	1,269	9,310	-980	7,065
Total discontinued operations	929	-2,130	921	4,034
Net income (loss)	2,174	7,180	-71	11,099
Net income (Loss) attributable to Brandywine Realty Trust	$2,198	$7,180	($59)	$11,099

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income Statement (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Net income (loss)	$2,174	$7,180	($71)	$11,099
Comprehensive Income (Loss)	'	'	'	'
Unrealized gain (loss) on derivative financial instruments	-2,285	9,491	-3,265	11,283
Reclassification of realized (gains)/losses on derivative financial instruments to operations, net	60	66	120	168
Other comprehensive income (loss)	-2,225	9,557	-3,145	11,451
Comprehensive Income	-51	16,737	-3,216	22,550
Comprehensive (income) loss attributable to non-controlling interest	44	-169	86	-221
Comprehensive income (loss) attributable to Brandywine Realty Trust	-7	16,568	-3,130	22,329
BRANDYWINE OPERATING PARTNERSHIP, L.P.	'	'	'	'
Net income (loss)	2,174	7,180	-71	11,099
Comprehensive Income (Loss)	'	'	'	'
Unrealized gain (loss) on derivative financial instruments	-2,285	9,491	-3,265	11,283
Reclassification of realized (gains)/losses on derivative financial instruments to operations, net	60	66	120	168
Other comprehensive income (loss)	-2,225	9,557	-3,145	11,451
Comprehensive Income	($51)	$16,737	($3,216)	$22,550

Consolidated_Statements_of_Ben

Consolidated Statements of Beneficiaries' Equity (USD $)	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Deferred Compensation, Share-based Payments [Member]	Common Stock In Grantor Trust [Member]	Cumulative Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Cumulative Distributions [Member]	Noncontrolling Interest [Member]
In Thousands, except Share data
Beginning Balance at Dec. 31, 2012	$1,773,516	$40	$1,434	$2,780,194	$5,352	($5,352)	$479,734	($15,918)	($1,493,206)	$21,238
Beginning Balance, Shares at Dec. 31, 2012	'	4,000,000	143,538,733	'	290,745	'	'	'	'	'
Net income (loss)	11,099	'	'	'	'	'	11,011	'	'	88
Comprehensive Income (Loss)	11,451	'	'	'	'	'	'	11,317	'	134
Stock Issued During Period, Shares, New Issues	'	'	12,650,000	'	'	'	'	'	'	'
Stock Issued During Period, Value, New Issues	182,034	'	127	181,907	'	'	'	'	'	'
Equity Issuance Costs	-380	'	'	-380	'	'	'	'	'	'
Stock Issued During Period, Shares, Conversion of Units	'	'	81,998	'	'	'	'	'	'	'
Bonus Share Issuance, Shares	'	'	27,918	'	'	'	'	'	'	'
Stock Issued During Period, Value, Conversion of Units	0	'	1	1,240	'	'	'	'	'	-1,241
Bonus Share Issuance, Value	361	'	'	361	'	'	'	'	'	'
Share Based Compensation Activity, Shares	'	'	341,591	'	7,050	'	'	'	'	'
Share Based Compensation Activity, Value	5,219	'	3	5,207	'	'	9	'	'	'
Share Issuance from/to Deferred Compensation Plan, Shares	'	'	22,404	'	17,958	'	'	'	'	'
Share issuance from/to Deferred Compensation Plan, Value	0	'	'	'	164	-164	'	'	'	'
Adjustments to Non-controlling Interest	0	'	'	-739	'	'	'	'	'	739
Preferred Share distributions	-3,450	'	'	'	'	'	'	'	-3,450	'
Distributions declared ($0.30 per share)	-45,781	'	'	'	'	'	'	'	-45,240	-541
Ending Balance at Jun. 30, 2013	1,934,069	40	1,565	2,967,790	5,516	-5,516	490,754	-4,601	-1,541,896	20,417
Ending Balance, Shares at Jun. 30, 2013	'	4,000,000	156,662,644	'	315,753	'	'	'	'	'
Beginning Balance at Dec. 31, 2013	1,921,435	40	1,566	2,971,596	5,407	-5,407	522,528	-2,995	-1,592,515	21,215
Beginning Balance, Shares at Dec. 31, 2013	'	4,000,000	156,731,993	'	312,280	'	'	'	'	'
Net income (loss)	-71	'	'	'	'	'	-20	'	'	-51
Comprehensive Income (Loss)	-3,145	'	'	'	'	'	'	-3,110	'	-35
Equity Issuance Costs	-60	'	'	-60	'	'	'	'	'	'
Share Based Compensation Activity, Shares	'	'	279,913	'	'	'	'	'	'	'
Share Based Compensation Activity, Value	3,629	'	5	3,612	'	'	12	'	'	'
Share Issuance from/to Deferred Compensation Plan, Shares	'	'	79,077	'	74,808	'	'	'	'	'
Share issuance from/to Deferred Compensation Plan, Value	-90	'	'	-90	896	-896	'	'	'	'
Adjustments to Non-controlling Interest	0	'	'	12	'	'	'	'	'	-12
Preferred Share distributions	-3,450	'	'	'	'	'	'	'	-3,450	'
Distributions declared ($0.30 per share)	-47,806	'	'	'	'	'	'	'	-47,276	-530
Ending Balance at Jun. 30, 2014	$1,870,442	$40	$1,571	$2,975,070	$6,303	($6,303)	$522,520	($6,105)	($1,643,241)	$20,587
Ending Balance, Shares at Jun. 30, 2014	'	4,000,000	157,090,983	'	387,088	'	'	'	'	'

Consolidated_Statements_of_Ben1

Consolidated Statements of Beneficiaries' Equity (Parantheticals) (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cumulative Distributions [Member]	'	'
Common Stock, Dividends, Per Share, Declared	$0.30	$0.30
Noncontrolling Interest [Member]	'	'
Common Stock, Dividends, Per Share, Declared	$0.30	$0.30

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Net income (loss)	($71)	$11,099
Adjustments to reconcile net income (loss) to net cash from operating activities:	'	'
Depreciation and amortization	105,157	100,459
Amortization of deferred financing costs	2,386	2,344
Amortization of debt discount/(premium), net	-324	748
Amortization of stock compensation costs	3,752	4,048
Shares used for employee taxes upon vesting of share awards	-1,266	-1,061
Straight-line rent income	-7,183	-11,250
Amortization of acquired above (below) market leases, net	-3,698	-3,556
Straight-line ground rent expense	44	894
Provision for doubtful accounts	1,272	997
Net Gain (Loss) On Real Estate Venture Transactions, including real estate venture formation	-417	3,683
Net gain on sale of interests in real estate	-2,087	-3,044
Gain from remeasurement of investment in a real estate venture	-458	-7,847
Loss on early extinguishment of debt	0	1,116
Real estate venture income in excess of distributions	558	-2,031
Deferred financing obligation	-590	-896
Changes in assets and liabilities:	'	'
Accounts receivable	-6,328	2,035
Other assets	1,462	6,031
Accounts payable and accrued expenses	-2,815	-1,252
Deferred income, gains and rent	-116	608
Other liabilities	129	474
Net cash from operating activities	90,241	96,233
Cash flows from investing activities:	'	'
Acquisition of properties	-12,405	-20,758
Sales of properties, net	40,149	145,931
Distribution of sales proceeds from real estate venture	0	16,963
Proceeds from repayment of mortgage notes receivable	2,800	200
Capital expenditures for tenant improvements	-58,035	-46,828
Capital expenditures for redevelopments	-4,773	-4,676
Capital expenditures for developments	-19,270	-72
Reimbursement from real estate venture for pre-formation development costs	0	1,976
Advances for purchase of tenant assets, net of repayments	16	-693
Investment in unconsolidated Real Estate Ventures	-3,095	-12,568
Escrowed cash	1,758	558
Cash distributions from unconsolidated Real Estate Ventures in excess of cumulative equity income	5,329	3,445
Leasing costs	-13,862	-14,313
Net cash from (used in) investing activities	-61,388	69,165
Cash flows from financing activities:	'	'
Proceeds from Credit Facility borrowings	0	186,000
Repayments of Credit Facility borrowings	0	-255,000
Repayments of mortgage notes payable	-6,647	-5,537
Deferred financing obligation interest expense	0	466
Net proceeds from issuance of common shares	0	181,527
Repayments of unsecured notes	0	-12,912
Debt financing costs	-35	-6
Exercise of stock options	709	1,762
Distributions paid to shareholders	-50,710	-46,745
Distributions to noncontrolling interest	-541	-554
Net cash from (used in) financing activities	-57,224	49,001
Increase (Decrease) in cash and cash equivalents	-28,371	214,399
Cash and cash equivalents at beginning of period	263,207	1,549
Cash and cash equivalents at end of period	234,836	215,948
Supplemental disclosure:	'	'
Cash paid for interest, net of capitalized interest during the six months ended June 30, 2014 and 2013 of $2,726 and $1,305, respectively	66,869	67,844
Supplemental disclosure of non-cash activity:	'	'
Change in operating real estate related to a non-cash acquisition of an operating property	0	-21,649
Change in intangible assets, net related to non-cash acquisition of an operating property	0	-3,517
Change in acquired lease intangibles, net related to non-cash acquisition of an operating property	0	462
Change in investments in joint venture related to non-cash disposition of property	-5,897	0
Change in investments in joint venture related to non-cash acquisition of property	0	13,040
Change in operating real estate related to non-cash adjustment to land	0	-4,386
Change in receivable from settlement of acquisitions	619	0
Change in investments in real estate ventures related to a contribution of land	0	-6,058
Change in capital expenditures financed through accounts payable at period end	-639	-1,227
Change in capital expenditures financed through retention payable at period end	1,188	-348
Change in unfunded tenant allowance	-193	-244
BRANDYWINE OPERATING PARTNERSHIP, L.P.	'	'
Net income (loss)	-71	11,099
Adjustments to reconcile net income (loss) to net cash from operating activities:	'	'
Depreciation and amortization	105,157	100,459
Amortization of deferred financing costs	2,386	2,344
Amortization of debt discount/(premium), net	-324	748
Amortization of stock compensation costs	3,752	4,048
Shares used for employee taxes upon vesting of share awards	-1,266	-1,061
Straight-line rent income	-7,183	-11,250
Amortization of acquired above (below) market leases, net	-3,698	-3,556
Straight-line ground rent expense	44	894
Provision for doubtful accounts	1,272	997
Net Gain (Loss) On Real Estate Venture Transactions, including real estate venture formation	-417	3,683
Net gain on sale of interests in real estate	-2,087	-3,044
Gain from remeasurement of investment in a real estate venture	-458	-7,847
Loss on early extinguishment of debt	0	1,116
Real estate venture income in excess of distributions	558	-2,031
Deferred financing obligation	-590	-896
Changes in assets and liabilities:	'	'
Accounts receivable	-6,328	2,035
Other assets	1,462	6,031
Accounts payable and accrued expenses	-2,815	-1,252
Deferred income, gains and rent	-116	608
Other liabilities	129	474
Net cash from operating activities	90,241	96,233
Cash flows from investing activities:	'	'
Acquisition of properties	-12,405	-20,758
Sales of properties, net	40,149	145,931
Distribution of sales proceeds from real estate venture	0	16,963
Proceeds from repayment of mortgage notes receivable	2,800	200
Capital expenditures for tenant improvements	-58,035	-46,828
Capital expenditures for redevelopments	-4,773	-4,676
Capital expenditures for developments	-19,270	-72
Reimbursement from real estate venture for pre-formation development costs	0	1,976
Advances for purchase of tenant assets, net of repayments	16	-693
Investment in unconsolidated Real Estate Ventures	-3,095	-12,568
Escrowed cash	1,758	558
Cash distributions from unconsolidated Real Estate Ventures in excess of cumulative equity income	5,329	3,445
Leasing costs	-13,862	-14,313
Net cash from (used in) investing activities	-61,388	69,165
Cash flows from financing activities:	'	'
Proceeds from Credit Facility borrowings	0	186,000
Repayments of Credit Facility borrowings	0	-255,000
Repayments of mortgage notes payable	-6,647	-5,537
Deferred financing obligation interest expense	0	466
Net proceeds from issuance of common shares	0	181,527
Repayments of unsecured notes	0	-12,912
Debt financing costs	-35	-6
Exercise of stock options	709	1,762
Distributions paid to shareholders	-51,251	-47,299
Net cash from (used in) financing activities	-57,224	49,001
Increase (Decrease) in cash and cash equivalents	-28,371	214,399
Cash and cash equivalents at beginning of period	263,207	1,549
Cash and cash equivalents at end of period	234,836	215,948
Supplemental disclosure:	'	'
Cash paid for interest, net of capitalized interest during the six months ended June 30, 2014 and 2013 of $2,726 and $1,305, respectively	66,869	67,844
Supplemental disclosure of non-cash activity:	'	'
Change in operating real estate related to a non-cash acquisition of an operating property	0	-21,649
Change in intangible assets, net related to non-cash acquisition of an operating property	0	-3,517
Change in acquired lease intangibles, net related to non-cash acquisition of an operating property	0	462
Change in investments in joint venture related to non-cash disposition of property	-5,897	0
Change in investments in joint venture related to non-cash acquisition of property	0	13,040
Change in operating real estate related to non-cash adjustment to land	0	-4,386
Change in receivable from settlement of acquisitions	619	0
Change in investments in real estate ventures related to a contribution of land	0	-6,058
Change in capital expenditures financed through accounts payable at period end	-639	-1,227
Change in capital expenditures financed through retention payable at period end	1,188	-348
Change in unfunded tenant allowance	($193)	($244)

Consolidated_Statement_of_Cash

Consolidated Statement of Cash Flows (Parentheticals) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Supplemental Cash Flow Information [Abstract]	'	'
Capitalized interest	$2,726	$1,305
BRANDYWINE OPERATING PARTNERSHIP, L.P.	'	'
Supplemental Cash Flow Information [Abstract]	'	'
Capitalized interest	$2,726	$1,305

Organization_of_the_Parent_Com

Organization of the Parent Company and The Operating Partnership	6 Months Ended
	Jun. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
ORGANIZATION OF THE PARENT COMPANY AND THE OPERATING PARTNERSHIP [Text Block]	'
	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, industrial, 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 June 30, 2014, owned a 98.9% 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 June 30, 2014, the Company owned 205 properties, consisting of 175 office properties, 20 industrial facilities, five mixed-use properties, one retail property (201 core properties), two development properties, one redevelopment property and one re-entitlement property (collectively, the “Properties”) containing an aggregate of approximately 25.4 million net rentable square feet. In addition, as of June 30, 2014, the Company owned economic interests in 17 unconsolidated real estate ventures that own properties containing an aggregate of approximately 5.9 million net rentable square feet (collectively, the “Real Estate Ventures”). As of June 30, 2014, the Company also owned 419 acres of undeveloped land, and held options to purchase approximately 50 additional acres of undeveloped land. As of June 30, 2014, these land parcels could support, under current zoning and entitlements, approximately 5.9 million square feet of development. 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; Richmond, Virginia; Wilmington, Delaware; Austin, Texas and Oakland, Concord and Carlsbad, California.
	The Company conducts its third-party real estate management services business primarily through wholly-owned management company subsidiaries. As of June 30, 2014, the management company subsidiaries were managing properties containing an aggregate of approximately 33.5 million net rentable square feet, of which approximately 25.4 million net rentable square feet related to Properties owned by the Company and approximately 8.1 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.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Text Block]	'
	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	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 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 June 30, 2014, the results of its operations for the three and six-month periods ended June 30, 2014 and 2013 and its cash flows for the six-month periods ended June 30, 2014 and 2013 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 2013 Annual Report on Form 10-K filed with the SEC on February 25, 2014.
	Reclassifications
	Certain amounts have been reclassified in prior years to conform to the current year presentation, including the reclassification of notes receivable to other assets within the balance sheets and the reclassification of changes in escrow balances from operating cash flows to investing cash flows in the statements of cash flows. All other reclassifications are related to the treatment of sold properties as discontinued operations on the statement of operations for all periods presented. See Recent Accounting Pronouncements below for revisions to the accounting guidance for discontinued operations.
	Recent Accounting Pronouncements
	In May 2014 the Financial Accounting Standards Board (FASB) issued guidance requiring revenue to be recognized in an amount that reflects the consideration expected to be received in exchange for those goods and services. The guidance requires the disclosure of sufficient quantitative and qualitative information for financial statement users to understand the nature, amount, timing and uncertainty of revenue and associated cash flows arising from contracts with customers. The guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period, with early adoption precluded. The Company has not yet determined the impact, if any, that the adoption of this guidance will have on its consolidated financial position or results of operations.
	In April 2014 the FASB issued revised guidance on discontinued operations and disclosures of disposals of components of an entity. The update revises the definition to include only disposals involving a strategic shift that has a major effect on the entity’s operations and financial results when the disposal asset or group meets the existing criterion for treatment as held for sale. Examples of a strategic shift include the withdrawal from a major geographic area, line of business, equity method investment or any other major parts of a business, as applicable. A component of the entity comprises operations and cash flows that can be clearly distinguished, operationally and for financial reporting purposes, from the rest of the entity. In addition, the revised standard no longer precludes presentation as a discontinued operation if there are operations and cash flows of the component that have not been eliminated from the reporting entity’s ongoing operations, or if there is significant continuing involvement with a component after its disposal.
	The amendments require additional disclosures about discontinued operations including; the major classes of net income or loss where net income is otherwise presented, the operating and investing cash flows of discontinued operations where net income is otherwise presented, depreciation, amortization, capital expenditures and significant operating and investing non-cash items of the discontinued operation for the periods in which net income is otherwise presented and, if there is a non-controlling interest, the related allocation to the parent company.
	Application is prospective, and required for periods beginning on or after December 15, 2014. This update should not be applied to assets classified as held for sale before the effective date even if the component of an entity is disposed of after the effective date. Early adoption is permitted for disposals or assets held for sale that have not been reported in the financial statements previously issued or available for issuance. The Company has elected to early adopt this standard as of January 1, 2014. All properties sold or determined held for sale prior to January 1, 2014 are classified as discontinued operations for all periods presented.

Real_Estate_Investments

Real Estate Investments	6 Months Ended
	Jun. 30, 2014
Real Estate [Abstract]	'
Real Estate Disclosure [Text Block]	'
	REAL ESTATE INVESTMENTS
	As of June 30, 2014 and December 31, 2013, the gross carrying value of the Company’s Properties was as follows (in thousands):
		June 30,		December 31,
		2014		2013
	Land	$	688,775	$	680,513
	Building and improvements	3,479,850		3,504,060
	Tenant improvements	521,267		484,716
		$	4,689,892	$	4,669,289
	Acquisitions
	As of June 30, 2014, a $0.5 million gain on remeasurement of the Company's investment in partnerships with Parkway Properties, Inc. was recorded. On December 19, 2013, the Company increased its equity ownership interest from 25% to 99% in each of the two partnerships that own One and Two Commerce Square, two 41-story trophy-class office towers in Philadelphia, Pennsylvania. As of December 31, 2013, the Company had recorded a $1.6 million net receivable balance from its former partner which represented the former partner's portion of the net current assets (liabilities) pursuant to the terms of the Commerce Square Redemption Agreement. Pursuant to the Redemption Agreement, the Company and Parkway used an agreed upon settlement period to finalize the purchase accounting related to facts and circumstances that existed at the date of the acquisition but were not fully known at such time. During the quarter ended June 30, 2014, $2.1 million of consideration was received from the former partner in full settlement of the aforementioned provision and a measurement period adjustment was made to adjust the fair value of the Company's previously held equity investment, resulting in a gain on remeasurement of the Company's investment in the partnerships of $0.5 million. For additional information related to this transaction, see the audited financial statements included in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2013.
	On February 19, 2014, the Company acquired 54.1 acres of undeveloped land known as Encino Trace in Austin, Texas for $14.0 million. The land is fully entitled with a site plan and building permits in place allowing for the development of two four-story office buildings containing approximately 320,000 net rentable square feet. The purchase price included an in-place lease, which was placed into construction in progress. As such, the Company has treated this transaction as a business combination and allocated the purchase price to the tangible and intangible assets. The Company capitalized $8.4 million in construction in progress, recorded $4.6 million in land inventory and recorded a deposit for a portion of the future development fee held in escrow for $1.0 million. The net assets were purchased using available corporate funds.
	As of June 30, 2014, both of the office buildings at Encino Trace are currently in development with $18.7 million, inclusive of the $14.0 million acquisition cost, funded through June 30, 2014. During the second quarter of 2014, the Company reclassified the $4.6 million remaining in land inventory to construction in progress in connection with commencing development of the second building. Additional project costs will be funded over the remaining construction period, which is scheduled to be completed during the second quarter of 2015.
	Dispositions
	On April 16, 2014, the Company sold a 5.3 acre parcel of land located in Dallas, Texas for a sales price of $1.6 million resulting in a nominal gain on sale after closing and other transaction related costs. The land parcel was undeveloped as of the date of sale.
	On April 7, 2014, the Company received $0.9 million from an escrow account that was established in connection with the sale of eight office properties containing 800,546 square feet in Lawrenceville, New Jersey, known as "Princeton Pike Corporate Center." The sale of Princeton Pike Corporate Center was completed on February 25, 2013 for an aggregate sales price of $121.0 million and resulted in a $5.3 million gain on sale after closing and other transaction related costs. The escrow account was funded with $2.0 million at closing and was established for use by the buyer to fund certain tenant improvement projects with any unused portion to be returned to the Company. The unused amount received from the escrow account was recognized as a gain on sale during the period ended June 30, 2014. The aforementioned gain was recognized within discontinued operations which is consistent with the accounting classification of the assets that were disposed of on February 25, 2013.
	On April 3, 2014, the Company contributed two 3-story, Class A office buildings, containing an aggregate of approximately 192,396 net rentable square feet known as Four Points Centre in Austin, Texas to an existing real estate venture (the "Austin Venture") that the Company formed in 2013 with G&I VII Austin Office LLC, an investment vehicle advised by DRA Advisors LLC ("DRA"). The Company contributed the properties to the Austin Venture at an agreed upon value of $41.5 million. In conjunction with the contribution: (i) the Austin Venture obtained a $29.0 million mortgage loan; (ii) the DRA member contributed $5.9 million in net cash to the capital of the Austin Venture; and (iii) the Austin Venture distributed $34.4 million to the Company and credited the Company with a $5.9 million capital contribution to the Austin Venture. The Company incurred a $0.2 million loss on the contribution, driven primarily by closing costs. The disposal of Four Points Centre does not represent a strategic shift that has a major effect on the Company's operations and financial results. Accordingly, the property remains classified within continuing operations.
	On March 27, 2014, the Company sold a 16.8 acre undeveloped parcel of land located in Austin, Texas for a sales price of $3.5 million resulting in a $1.2 million gain on sale of undepreciated real estate after closing and other transaction related costs. The land parcel was undeveloped as of the date of sale.

Investment_in_Unconsolidated_V

Investment in Unconsolidated Ventures	6 Months Ended
	Jun. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Equity Method Investments and Joint Ventures Disclosure [Text Block]	'
	INVESTMENT IN UNCONSOLIDATED VENTURES
	As of June 30, 2014, the Company held ownership interests in 17 unconsolidated Real Estate Ventures, of which $186.0 million is included in assets and $1.2 million is included in other liabilities relating to the negative investment balance of one real estate venture. The Company formed or acquired interests in these ventures with unaffiliated third parties to develop or manage office properties or to acquire land in anticipation of possible development of office or residential properties. As of June 30, 2014, 11 of the Real Estate Ventures owned 56 office buildings that contain an aggregate of approximately 5.9 million net rentable square feet; two Real Estate Ventures owned 3.8 acres of undeveloped parcels of land; three Real Estate Venture owned 22.5-acres of land under active development and one Real Estate Venture owned a hotel property that contains 137 rooms in Conshohocken, PA.
	The Company accounts for its unconsolidated interests in its Real Estate Ventures using the equity method. The Company’s unconsolidated interests range from 20% to 65%, subject to specified priority allocations of distributable cash in certain of the Real Estate Ventures.
	The amounts reflected in the following tables (except for the Company’s share of equity and income) are based on the historical financial information of the individual Real Estate Ventures. The Company does not record operating losses of the Real Estate Ventures 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 as of June 30, 2014 and December 31, 2013 (in thousands):
		June 30,				December 31,
		2014				2013
	Net property	$	1,081,064			$	965,475
	Other assets	153,348				164,152
	Other liabilities	68,031				49,442
	Debt	792,919				699,860
	Equity	373,462				380,325
	Company’s share of equity (Company’s basis) (a)	186,042			(b)	180,512
	(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.
	(b) Does not include the negative investment balance of one real estate venture totaling $1.2 million as of June 30, 2014, which is included in other liabilities.
	The Company held interests in 17 Real Estate Ventures containing an aggregate of approximately 5.9 million net rentable square feet as of the three and six-month periods ended June 30, 2014 and 17 Real Estate Ventures containing an aggregate of approximately 6.2 million net rentable square feet as of the three and six-month periods ended June 30, 2013. The following is a summary of results of operations of the Real Estate Ventures in which the Company had interests during these periods (in thousands):
		Three-month periods ended June 30,							Six-month periods ended June 30,
		2014				2013			2014			2013
	Revenue	$	35,074			$	36,927		$	69,459		$	77,816
	Operating expenses	14,842				17,205			28,824			35,472
	Interest expense, net	8,889				9,173			16,989			18,944
	Depreciation and amortization	13,273				10,979			26,871			23,885
	Net loss	(1,930		)		(430		)	(3,225		)	(485		)
	Company’s share of income (loss) (Company’s basis)	(489		)		1,508			(247		)	3,043
	Austin Venture - Four Points Centre
	On April 3, 2014, the Company contributed two 3-story, Class A office buildings, containing an aggregate of approximately 192,396 net rentable square feet, known as Four Points Centre in Austin, Texas to the Austin Venture. See Note 3 for further information on the contribution.
	Guarantees
	As of June 30, 2014, the Company had provided guarantees on behalf of certain real estate ventures, consisting of (i) a $24.7 million payment guaranty on the construction loan for the project being undertaken by evo at Cira; (ii) a $3.2 million payment guarantee on the construction loan for the development project being undertaken by TB-BDN Plymouth Apartments; and (iii) a $0.5 million payment guarantee on a loan provided to PJP VII. In addition, during construction undertaken by Real Estate Ventures, the Company has provided and expects to continue to provide cost overrun and completion guarantees, with rights of contribution among partners in the real estate venture, as well as customary environmental indemnities and guarantees of customary exceptions to nonrecourse provisions in loan agreements. For additional information regarding these real estate ventures, see "Investments in Unconsolidated Ventures" in notes to the audited financial statements included in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2013.

Deferred_Costs

Deferred Costs	6 Months Ended
	Jun. 30, 2014
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]	'
Deferred Costs [Text Block]	'
	DEFERRED COSTS
	As of June 30, 2014 and December 31, 2013, the Company’s deferred costs were comprised of the following (in thousands):
		June 30, 2014
		Total Cost		Accumulated			Deferred Costs,
				Amortization			net
	Leasing Costs	$	161,800	$	(61,694	)	$	100,106
	Financing Costs	40,315		(16,829		)	23,486
	Total	$	202,115	$	(78,523	)	$	123,592
		December 31, 2013
		Total Cost		Accumulated			Deferred Costs,
				Amortization			net
	Leasing Costs	$	155,885	$	(58,805	)	$	97,080
	Financing Costs	40,317		(14,443		)	25,874
	Total	$	196,202	$	(73,248	)	$	122,954
	During each of the three and six-month periods ended June 30, 2014, the Company capitalized internal direct leasing costs of $2.0 million and $4.0 million, respectively, and $1.8 million and $3.9 million during the three and six-month periods ended June 30, 2013 in accordance with the accounting standard for the capitalization of leasing costs.
Components Of Deferred Costs Net [Table Text Block]	'
	As of June 30, 2014 and December 31, 2013, the Company’s deferred costs were comprised of the following (in thousands):
		June 30, 2014
		Total Cost		Accumulated			Deferred Costs,
				Amortization			net
	Leasing Costs	$	161,800	$	(61,694	)	$	100,106
	Financing Costs	40,315		(16,829		)	23,486
	Total	$	202,115	$	(78,523	)	$	123,592
		December 31, 2013
		Total Cost		Accumulated			Deferred Costs,
				Amortization			net
	Leasing Costs	$	155,885	$	(58,805	)	$	97,080
	Financing Costs	40,317		(14,443		)	25,874
	Total	$	196,202	$	(73,248	)	$	122,954

Intangible_Assets

Intangible Assets	6 Months Ended
	Jun. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Intangible Assets Disclosure [Text Block]	'
	INTANGIBLE ASSETS AND LIABILITIES
	As of June 30, 2014 and December 31, 2013, the Company’s intangible assets/liabilities were comprised of the following (in thousands):
		June 30, 2014
		Total Cost		Accumulated			Intangible assets/liabilities, net
				Amortization
	Intangible assets, net:
	In-place lease value	$	136,388	$	(38,767	)	$	97,621
	Tenant relationship value	37,019		(27,159		)	9,860
	Above market leases acquired	6,120		(1,461		)	4,659
	Total intangible assets, net	$	179,527	$	(67,387	)	$	112,140
	Acquired lease intangibles, net:
	Below market leases acquired	$	64,679	$	(35,563	)	$	29,116
		December 31, 2013
		Total Cost		Accumulated			Intangible assets/liabilities, net
				Amortization
	Intangible assets, net:
	In-place lease value	$	150,782	$	(35,607	)	$	115,175
	Tenant relationship value	38,692		(26,868		)	11,824
	Above market leases acquired	6,673		(1,343		)	5,330
	Total intangible assets, net	$	196,147	$	(63,818	)	$	132,329
	Acquired lease intangibles, net:
	Below market leases acquired	$	81,991	$	(47,547	)	$	34,444
	As of June 30, 2014, the Company’s annual amortization for its intangible assets/liabilities were as follows (in thousands, and assuming no prospective early lease terminations):
		Assets		Liabilities
	2014 (six months remaining)	$	12,075	$	3,093
	2015	21,581		5,223
	2016	17,102		3,254
	2017	15,279		2,664
	2018	11,458		2,241
	Thereafter	34,645		12,641
	Total	$	112,140	$	29,116

Debt_Obligations

Debt Obligations	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Debt Disclosure [Text Block]	'
	DEBT OBLIGATIONS
	The following table sets forth information regarding the Company’s consolidated debt obligations at June 30, 2014 and December 31, 2013 (in thousands):
	Property / Location	June 30, 2014			31-Dec-13			Effective			Maturity
								Interest			Date
								Rate
	MORTGAGE DEBT:
	Tysons Corner	$	90,460		$	91,395		5.36	%	(a)	Aug-15
	One Commerce Square	124,151			125,089			3.68	%	(a)	Jan-16
	Two Logan Square	88,174			88,583			7.57	%		Apr-16
	Fairview Eleven Tower	21,470			21,630			4.25	%	(b)	Jan-17
	Two Commerce Square	112,000			112,000			4.51	%	(a)	Apr-23
	Cira Square (GSA Philadelphia Campus)	187,751			190,964			7	%		Sep-30
	Cira Centre South Garage	38,950			40,101			7.12	%		Sep-30
	Principal balance outstanding	662,956			669,762
	Plus: fair market value premiums (discounts), net	(478		)	389
	Total mortgage indebtedness	$	662,478		$	670,151
	UNSECURED DEBT:
	Three-Year Term Loan - Swapped to fixed	$	150,000		$	150,000		2.6	%		Feb-15
	Four-Year Term Loan	100,000			100,000			LIBOR + 1.75%		(c)	Feb-16
	Seven-Year Term Loan - Swapped to fixed	200,000			200,000			3.62	%		Feb-19
	$250.0M 5.400% Guaranteed Notes due 2014	218,549			218,549			5.53	%		Nov-14
	$250.0M 7.500% Guaranteed Notes due 2015	157,625			157,625			7.76	%		May-15
	$250.0M 6.000% Guaranteed Notes due 2016	149,919			149,919			5.95	%		Apr-16
	$300.0M 5.700% Guaranteed Notes due 2017	300,000			300,000			5.68	%		May-17
	$325.0M 4.950% Guaranteed Notes due 2018	325,000			325,000			5.13	%		Apr-18
	$250.0M 3.950% Guaranteed Notes due 2023	250,000			250,000			4.02	%		Feb-23
	Indenture IA (Preferred Trust I)	27,062			27,062			2.75	%		Mar-35
	Indenture IB (Preferred Trust I)	25,774			25,774			3.3	%		Apr-35
	Indenture II (Preferred Trust II)	25,774			25,774			3.09	%		Jul-35
	Principal balance outstanding	1,929,703			1,929,703
	Plus: original issue premiums (discounts), net	(3,931		)	(4,473		)
	Total unsecured indebtedness	$	1,925,772		$	1,925,230
	Total Debt Obligations	$	2,588,250		$	2,595,381
	(a)	These loans were assumed upon acquisition of the related properties. The interest rate reflects the market rate at the time of acquisition.
	(b)	Represents the full debt amount secured by a property owned by a consolidated real estate venture in which the Company holds a 50% interest.
	(c)	London Interbank Offered Rate (“LIBOR”).
	During the six-month periods ended June 30, 2014 and 2013, the Company’s weighted-average effective interest rate on its mortgage notes payable was 5.73% and 6.64%, respectively.
	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 utilizes its unsecured revolving credit facility (the "Credit Facility") for general business purposes, including funding costs of acquisitions, developments and redevelopments and repayment of other debt. The scheduled maturity date of the Credit Facility in place at June 30, 2014 is February 1, 2016. The per annum variable interest rate on balances outstanding under the Credit Facility is LIBOR plus 1.50%. The interest rate and facility fee are subject to adjustment upon a change in the Company’s unsecured debt ratings. As of June 30, 2014, the Company did not have any outstanding borrowings on its Credit Facility, with $1.5 million in letters of credit outstanding, leaving $598.5 million of unused availability under the Credit Facility. During each of the three and six-month periods ended June 30, 2014 and 2013, there were no weighted-average interest rates associated with the Credit Facility because there were no borrowings outstanding under the Credit Facility during either period.
	The Company has the option to increase the amounts available to be advanced under the Credit Facility, the $150.0 million three-year term loan, and the $100.0 million four-year term loan by an aggregate of $200.0 million, subject to customary conditions and limitations, by obtaining additional commitments from the current lenders and other financial institutions. The Company also has the option to extend by one year the maturity dates of each of the Credit Facility, the $150.0 million three-year term loan and the $100.0 million four-year term loan subject to payment of an extension fee and other customary conditions and limitations. The Company may repay the $150.0 million three-year term loan and the $100.0 million four-year term loan at any time without penalty. The $200.0 million seven-year term loan is subject to a prepayment penalty of 1.00% through February 1, 2015 with no penalty thereafter.
	The spread to LIBOR for LIBOR-based loans under the Credit Facility and term loans depends on the Company's unsecured senior debt credit rating. Based on the Company's current credit rating, the spread for such loans will be 150 basis points under the Credit Facility, 175 basis points under both the $150.0 million three-year term loan and the $100.0 million four-year term loan and 190 basis points under the $200.0 million seven-year term loan. At the Company's option, advances under the Credit Facility and term loans may also bear interest at a per annum floating rate equal to the higher of the prime rate or the federal funds rate plus 0.50% per annum. The Credit Facility contains a competitive bid option that allows banks that are part of the lender consortium to bid on loans to the Company at a reduced rate.
	The Company executed hedging transactions that fix the rate on the $200.0 million seven-year term loan at a 3.623% average rate for its full term, and the rate on the $150.0 million three-year term loan at a 2.596% average rate for periods of three to four years. All hedges commenced on February 1, 2012 and the rates are inclusive of the LIBOR spread based on the Company's current investment grade rating. See Note 9 for details of the interest rate swaps entered into as of June 30, 2014.
	The Credit Facility and term loans contain financial and operating covenants and restrictions. The Company was in compliance with all such restrictions and financial covenants as of June 30, 2014. In the event of a default related to the financing and operating covenants, the Company's dividend distributions are limited to the greater of 95% of funds from operations or the minimum amount necessary for the Company to maintain its status as a REIT.
	As of June 30, 2014, the Company’s aggregate scheduled principal payments on debt obligations, excluding amortization of discounts and premiums, were as follows (in thousands):
	2014 (six months remaining)	$	225,570
	2015	409,655
	2016	467,703
	2017	330,323
	2018	336,954
	Thereafter	822,454
	Total principal payments	2,592,659
	Net unamortized premiums/(discounts)	(4,409		)
	Outstanding indebtedness	$	2,588,250

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Disclosures [Text Block]	'
	FAIR VALUE OF FINANCIAL INSTRUMENTS
	The Company determined the fair values disclosed below using available market information and discounted cash flow analyses as of June 30, 2014 and December 31, 2013, 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 June 30, 2014 and December 31, 2013 approximate the fair values for cash and cash equivalents, accounts receivable, other assets, 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):
		June 30, 2014				December 31, 2013
		Carrying		Fair		Carrying		Fair
		Amount		Value		Amount		Value
	Unsecured notes payable	$	1,397,162	$	1,478,767	$	1,396,620	$	1,471,041
	Variable rate debt	$	528,610	$	504,044	$	528,610	$	526,693
	Mortgage notes payable	$	662,478	$	697,731	$	670,151	$	715,244
	Notes receivable	$	4,226	$	5,088	$	7,026	$	7,759
	The fair value of the Company's unsecured notes payable are categorized as Level 2 (as provided by the accounting standard for Fair Value Measurements and Disclosures), as these instruments are valued using quoted market prices as of June 30, 2014 and December 31, 2013.
	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 fully secured loans with similar terms and maturities. The weighted average discount rate for the combined variable rate debt and mortgage loans as of June 30, 2014 was 3.467%. The fair value of the notes receivable was estimated using the expected cash flows of the notes receivable, and discounting those cash flows using the market rate of interest for mortgage notes with a comparable level of risk. The Company used a discount rate of 14.82% for the notes receivable as of June 30, 2014. The Company applies its knowledge of the debt markets to determine appropriate discount rates to utilize in the discounted cash flow models. As these inputs are unobservable, the Company has categorized the valuation of mortgage notes payable, variable rate debt and notes receivable as Level 3 (as provided by the accounting standard for Fair Value Measurements and Disclosures).
	Disclosure about the fair value of financial instruments is based upon pertinent information available to management as of June 30, 2014 and December 31, 2013. 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 June 30, 2014, and current estimates of fair value may differ from the amounts presented herein.

Risk_Management_and_Use_of_Fin

Risk Management and Use of Financial Instruments	6 Months Ended
	Jun. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
RISK MANAGEMENT AND USE OF FINANCIAL INSTRUMENTS [Text Block]	'
	FAIR VALUE OF DERIVATIVE FINANCIAL INSTRUMENTS
	The following table summarizes the terms and fair values of the Company's derivative financial instruments as of June 30, 2014 and December 31, 2013. 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 liabilities on the Company's consolidated balance sheets).
	Hedge Product	Hedge Type	Designation		Notional Amount				Strike		Trade Date	Maturity Date	Fair value
					6/30/14		12/31/13						6/30/14			12/31/13
	Assets (Liabilities):
	Swap	Interest Rate	Cash Flow	(a)	$	200,000	$	200,000	3.623	%	December 6-13, 2011	February 1, 2019	$	(2,843	)	$	(545	)
	Swap	Interest Rate	Cash Flow	(a)	77,000		77,000		2.703	%	December 9-13, 2011	February 1, 2016	(799		)	(887		)
	Swap	Interest Rate	Cash Flow	(a)	50,000		50,000		2.47	%	December 13, 2011	February 1, 2015	(191		)	(283		)
	Swap	Interest Rate	Cash Flow	(a)	27,062		27,062		2.75	%	December 21, 2011	September 30, 2017	(385		)	(311		)
	Swap	Interest Rate	Cash Flow	(a)	25,774		25,774		3.3	%	December 22, 2011	January 30, 2021	(128		)	549
	Swap	Interest Rate	Cash Flow	(a)	25,774		25,774		3.09	%	6-Jan-12	30-Oct-19	(214		)	218
	Swap	Interest Rate	Cash Flow	(a)	23,000		23,000		2.513	%	December 7-12, 2011	May 1, 2015	(125		)	(162		)
					$	428,610	$	428,610					$	(4,685	)	$	(1,421	)
	(a) Hedging unsecured variable rate debt.
	The Company measures its derivative instruments at fair value and records them in the balance sheet as either an asset or liability. As of June 30, 2014, all swaps are included in other liabilities on the Company's consolidated balance sheet.
	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.

Discontinued_Operations

Discontinued Operations	6 Months Ended
	Jun. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
DISCONTINUED OPERATIONS [Text Block]	'
	DISCONTINUED OPERATIONS
	The Company had no property dispositions classified as discontinued operations during the three and six months ended June 30, 2014. There was nominal income before gain on sales recognized during 2014 relating to properties classified into discontinued operations in prior periods and a $0.9 million gain relating to the post closing activity for the sale of the Princeton Pike Corporate Center completed in the first quarter of 2013. See Note 3 for further information.
	For the three and six-month periods ended June 30, 2013, income from discontinued operations relates to the 14 properties sold by the Company from January 1, 2013 through December 31, 2013. The following table summarizes the revenue and expense information for properties classified as discontinued operations for the three and six-month periods ended June 30, 2013 (in thousands):
		Three-month period ended June 30, 2013			Six-month period ended
					30-Jun-13
	Revenue:
	Rents	$	895		$	4,658
	Tenant reimbursements	7			345
	Termination fees	—			—
	Other	9			123
	Total revenue	911			5,126
	Expenses:
	Property operating expenses	330			1,711
	Real estate taxes	118			584
	Depreciation and amortization	337			1,845
	Total operating expenses	785			4,140
	Other income:
	Interest income	3			3
	Income from discontinued operations before gain on sale of interests in real estate	129			989
	Net gain on disposition of discontinued operations	(2,259		)	3,045
	Income from discontinued operations	$	(2,130	)	$	4,034
	Discontinued operations have not been segregated in the consolidated statements of cash flows. Therefore, amounts for certain captions will not agree with respective data in the consolidated statements of operations.

Non_Controlling_Interests_In_t

Non Controlling Interests In the Parent Company	6 Months Ended
	Jun. 30, 2014
Noncontrolling Interest [Abstract]	'
NON-CONTROLLING INTERESTS IN THE PARENT COMPANY [Text Block]	'
	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 as of June 30, 2014 and December 31, 2013 was $19.7 million and $20.3 million, 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 date) was approximately $27.5 million and $24.8 million, respectively, as of June 30, 2014 and December 31, 2013.

Beneficiaries_Equity_of_the_Pa

Beneficiaries Equity of the Parent Company	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
BENEFICIARIES' EQUITY OF THE PARENT COMPANY [Text Block]	'
	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 June 30,
		2014						2013
		Basic			Diluted			Basic			Diluted
	Numerator
	Income from continuing operations	$	1,245		$	1,245		$	9,310		$	9,310
	Income (loss) from continuing operations attributable to non-controlling interests	5			5			(87		)	(87		)
	Net loss attributable to non-controlling interest — partners' share of consolidated real estate ventures	24			24			—			—
	Nonforfeitable dividends allocated to unvested restricted shareholders	(83		)	(83		)	(85		)	(85		)
	Preferred share dividends	(1,725		)	(1,725		)	(1,725		)	(1,725		)
	Income (loss) from continuing operations available to common shareholders	(534		)	(534		)	7,413			7,413
	Income (loss) from discontinued operations	929			929			(2,130		)	(2,130		)
	Discontinued operations attributable to non-controlling interests	(10		)	(10		)	25			25
	Discontinued operations attributable to common shareholders	919			919			(2,105		)	(2,105		)
	Net income attributable to common shareholders	$	385		$	385		$	5,308		$	5,308
	Denominator
	Weighted-average shares outstanding	157,037,348			157,037,348			155,347,384			155,347,384
	Contingent securities/Share based compensation	—			—			—			1,343,817
	Weighted-average shares outstanding	157,037,348			157,037,348			155,347,384			156,691,201
	Earnings per Common Share:
	Income from continuing operations attributable to common shareholders	$	—		$	—		$	0.05		$	0.05
	Discontinued operations attributable to common shareholders	—			—			(0.02		)	(0.02		)
	Net income attributable to common shareholders	$	—		$	—		$	0.03		$	0.03
		Six-month periods ended June 30,
		2014						2013
		Basic			Diluted			Basic			Diluted
	Numerator
	Income (loss) from continuing operations	$	(992	)	$	(992	)	$	7,065		$	7,065
	(Income) loss from continuing operations attributable to non-controlling interests	49			49			(37		)	(37		)
	Net loss attributable to non-controlling interest — partners' share of consolidated real estate ventures	12			12			—			—
	Nonforfeitable dividends allocated to unvested restricted shareholders	(186		)	(186		)	(193		)	(193		)
	Preferred share dividends	(3,450		)	(3,450		)	(3,450		)	(3,450		)
	Income (loss) from continuing operations available to common shareholders	(4,567		)	(4,567		)	3,385			3,385
	Income from discontinued operations	921			921			4,034			4,034
	Discontinued operations attributable to non-controlling interests	(10		)	(10		)	(53		)	(53		)
	Discontinued operations attributable to common shareholders	911			911			3,981			3,981
	Net income (loss) attributable to common shareholders	$	(3,656	)	$	(3,656	)	$	7,366		$	7,366
	Denominator
	Weighted-average shares outstanding	156,916,356			156,916,356			149,508,957			149,508,957
	Contingent securities/Share based compensation	—			—			—			1,157,288
	Weighted-average shares outstanding	156,916,356			156,916,356			149,508,957			150,666,245
	Earnings per Common Share:
	Income (loss) from continuing operations attributable to common shareholders	$	(0.03	)	$	(0.03	)	$	0.02		$	0.02
	Discontinued operations attributable to common shareholders	0.01			0.01			0.03			0.03
	Net income (loss) attributable to common shareholders	$	(0.02	)	$	(0.02	)	$	0.05		$	0.05
	Redeemable common limited partnership units totaling 1,763,739 as of June 30, 2014 and 2013, respectively, were excluded from the diluted earnings per share computations because they are not dilutive.
	Unvested restricted shares are considered participating securities which require the use of the two-class method for the computation of basic and diluted earnings per share. For the three and six-month periods ended June 30, 2014 and 2013, 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 May 29, 2014, the Parent Company declared a distribution of $0.15 per common share, totaling $23.6 million, which was paid on July 21, 2014 to shareholders of record as of July 7, 2014. In addition, the Parent Company declared distributions on its Series E Preferred Shares to holders of record as of June 30, 2014. These shares are entitled to a preferential return of 6.90% per annum on the $25.00 per share liquidation preference. Distributions paid on July 15, 2014 to holders of Series E Preferred Shares totaled $1.7 million.
	On May 15, 2014, the Company amended its Amended and Restated Declaration of Trust authorizing an increase in the Company’s total number of shares of beneficial interest from 220,000,000 to 420,000,000 shares, with the number of authorized common shares of beneficial interest increased from 200,000,000 to 400,000,000 and the number of authorized preferred shares of beneficial interest remaining unchanged at 20,000,000.
	On November 5, 2013, the Parent Company commenced a continuous equity offering program (the “Offering Program”), under which it may sell, in at-the-market offerings, up to an aggregate amount of 16,000,000 common shares until November 5, 2016. The Parent Company may sell common shares in amounts and at times to be determined by the Parent Company. Actual sales will depend on a variety of factors to be determined by the Parent Company, including, among others, market conditions, the trading price of the Company’s common shares and determinations by the Parent Company of the appropriate sources of funding. Sales agents engaged by the Parent Company under the Offering Program are entitled to receive, as compensation and in aggregate, up to 2% of the gross sales price per share sold under the Offering Program. From inception of the Offering Program through June 30, 2014, the Parent Company had not sold any shares under the program, leaving 16,000,000 remaining shares available for sale.
	Common Share Repurchases
	The Parent Company maintains a share repurchase program under which it may repurchase its common shares from time to time in accordance with limits set by the Board of Trustees.
	The Parent Company did not repurchase any shares under the share repurchase program during the six-month periods ended June 30, 2014 and 2013. As of June 30, 2014, the Parent Company may purchase up to 539,200 shares under the program.
	Repurchases may be made from time to time in the open market or in privately negotiated transactions, subject to market conditions and compliance with legal requirements. The share repurchase program does not contain any time limitation and does not obligate the Parent Company to repurchase any shares. The Parent Company may discontinue the program at any time.

Partners_Equity_of_the_Operati

Partners Equity of the Operating Partnership	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Partners Equity of Operating Partnership [Text Block]	'
	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 June 30,
		2014						2013
		Basic			Diluted			Basic			Diluted
	Numerator
	Income from continuing operations	$	1,245		$	1,245		$	9,310		$	9,310
	Nonforfeitable dividends allocated to unvested restricted unitholders	(83		)	(83		)	(85		)	(85		)
	Preferred unit dividends	(1,725		)	(1,725		)	(1,725		)	(1,725		)
	Net income attributable to non-controlling interests	24			24			—			—
	Income (loss) from continuing operations available to common unitholders	(539		)	(539		)	7,500			7,500
	Discontinued operations attributable to common unitholders	929			929			(2,130		)	(2,130		)
	Net income attributable to common unitholders	$	390		$	390		$	5,370		$	5,370
	Denominator
	Weighted-average units outstanding	158,801,087			158,801,087			157,131,697			157,131,697
	Contingent securities/Share based compensation	—			—			—			1,343,817
	Total weighted-average units outstanding	158,801,087			158,801,087			157,131,697			158,475,514
	Earnings per Common Partnership Unit:
	Income from continuing operations attributable to common unitholders	$	—		$	—		$	0.05		$	0.05
	Discontinued operations attributable to common unitholders	—			—			(0.02		)	(0.02		)
	Net income attributable to common unitholders	$	—		$	—		$	0.03		$	0.03
		Six-month periods ended June 30,
		2014						2013
		Basic			Diluted			Basic			Diluted
	Numerator
	Income (loss) from continuing operations	$	(992	)	$	(992	)	$	7,065		$	7,065
	Amount allocable to unvested restricted unitholders	(186		)	(186		)	(193		)	(193		)
	Preferred unit dividends	(3,450		)	(3,450		)	(3,450		)	(3,450		)
	Net income attributable to non-controlling interests	12			12			—			—
	Income (loss) from continuing operations available to common unitholders	(4,616		)	(4,616		)	3,422			3,422
	Discontinued operations attributable to common unitholders	921			921			4,034			4,034
	Net income (loss) attributable to common unitholders	$	(3,695	)	$	(3,695	)	$	7,456		$	7,456
	Denominator
	Weighted-average units outstanding	158,680,095			158,680,095			151,323,813			151,323,813
	Contingent securities/Share based compensation	—			—			—			1,157,288
	Total weighted-average units outstanding	158,680,095			158,680,095			151,323,813			152,481,101
	Earnings per Common Partnership Unit:
	Income (loss) from continuing operations attributable to common unitholders	$	(0.03	)	$	(0.03	)	$	0.02		$	0.02
	Discontinued operations attributable to common unitholders	0.01			0.01			0.03			0.03
	Net income (loss) attributable to common unitholders	$	(0.02	)	$	(0.02	)	$	0.05		$	0.05
	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 six-month periods ended June 30, 2014 and 2013, earnings representing nonforfeitable dividends as noted in the table above were allocated to the unvested restricted units issued to the Parent Company’s executives and other employees under the Parent Company's shareholder-approved long-term incentive plan.
	Common Partnership Units and Preferred Mirror Units
	The common partnership units not held by the Parent Company have the same economic characteristics as the Parent Company's common shares and share proportionately in the net income or loss and in any distributions of the Operating Partnership. The common partnership units not held by the Parent Company are redeemable at any time at the option of the holder, and the Parent Company, as the sole general partner of the Operating Partnership, may at its option elect to settle the redemption in cash or through the exchange on a one-for-one basis with common shares of the Parent Company. Similarly, the Series E-Linked Preferred Mirror Units of the Operating Partnership have the same economic characteristics as the Series E Preferred Shares of the Parent Company. Whenever the Parent Company issues common shares or preferred shares, it contributes the net proceeds to the Operating Partnership in exchange for, as applicable, an equal number of common partnership units or preferred units that mirror the economic terms of the preferred shares.
	On May 29, 2014, the Operating Partnership declared a distribution of $0.15 per common partnership unit, totaling $23.9 million, which was paid on July 21, 2014 to unitholders of record as of July 7, 2014. On May 29, 2014, the Operating Partnership declared distributions on its Series E-Linked Preferred Mirror Units to holders of record as of June 30, 2014. These units are entitled to a preferential return of 6.90% per annum on the $25.00 per unit liquidation preference. Distributions paid on July 15, 2014 to holders of Series E-Linked Preferred Mirror Units totaled $1.7 million.
	Common Unit Repurchases
	The Parent Company did not repurchase any shares under its share repurchase program in either of the six-month periods ended June 30, 2014 and 2013 and accordingly, during the six-month periods ended June 30, 2014 and 2013, the Operating Partnership did not repurchase any units in connection with the Parent Company’s share repurchase program.

Share_Based_and_Deferred_Compe

Share Based and Deferred Compensation	6 Months Ended
	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
SHARE BASED AND DEFERRED COMPENSATION	'
	SHARE BASED COMPENSATION
	Stock Options
	At June 30, 2014, options exercisable for 2,808,784 common shares were outstanding under the Parent Company's shareholder approved equity incentive plan (referred to as the "Equity Incentive Plan"). During the six-month period ended June 30, 2014 the Company recognized a nominal amount of compensation expense related to unvested options. During the three and six-month periods ended June 30, 2013 the Company recognized compensation expense related to unvested options of $0.2 million and $0.4 million, of which a nominal amount and $0.1 million, respectively, were capitalized consistent with the Company’s policies for capitalizing eligible portions of employee compensation.
	Option activity as of June 30, 2014 and changes during the six months ended June 30, 2014 were as follows:
		Shares		Weighted				Weighted Average		Aggregate Intrinsic
				Average				Remaining Contractual		Value
				Exercise Price				Term (in years)
	Outstanding at January 1, 2014	2,983,569		$	15.5			5.15		$	—
	Granted	—		$	—			—		—
	Exercised	(60,127	)	$	11.8			—		$	182,101
	Canceled	(114,658	)	$	20.61
	Outstanding at June 30, 2014	2,808,784		$	15.37			4.67		$	632,239
	Vested/Exercisable at June 30, 2014	2,808,784		$	15.37			4.67		$	632,239
	Restricted Share Awards
	As of June 30, 2014, 550,222 restricted shares were outstanding under the Equity Incentive Plan and vest over three years from the initial grant dates. The remaining compensation expense to be recognized at June 30, 2014 was approximately $2.9 million, and is expected to be recognized over a weighted average remaining vesting period of 1.9 years. During the three and six-month periods ended June 30, 2014, the Company recognized compensation expense related to outstanding restricted shares of $0.5 million and $1.9 million, of which $0.1 million and $0.4 million, respectively, were capitalized as part of the Company’s review of employee salaries eligible for capitalization. During the three and six-month periods ended June 30, 2013, the Company recognized compensation expense related to outstanding restricted shares of $0.9 million and $1.8 million, of which $0.1 million and $0.3 million, respectively, were capitalized consistent with the Company’s policies for capitalizing eligible portions of employee compensation.
	The following table summarizes the Company’s restricted share activity for the six months ended June 30, 2014:
		Shares		Weighted
				Average Grant
				Date Fair value
	Non-vested at January 1, 2014	563,713		$	12.56
	Granted	229,119		14.47
	Vested	(234,169	)	13.44
	Forfeited	(8,441	)	12.36
	Non-vested at June 30, 2014	550,222		$	12.22
	On March 11, 2014 and March 12, 2014 the Compensation Committee of the Parent Company’s Board of Trustees awarded restricted shares of which 131,641 cliff vest after three years from the grant date and 69,794 vest ratably over three years, of which 1,745 were canceled, leaving 68,049 unvested. In addition, on May 29, 2014, 27,684 restricted shares were granted and will vest ratably over three years. Restricted shares that cliff vest are subject to acceleration upon a change in control or if the recipient of the award were to die, become disabled or, in certain cases, retire in a qualifying retirement. Qualifying retirement generally means the recipient’s voluntary termination of employment after reaching at least age 57 and accumulating at least 15 years of service with the Company. In accordance with the accounting standard for stock-based compensation, the Company amortizes stock-based compensation costs through the qualifying retirement dates for those executives who meet the conditions for qualifying retirement during the scheduled vesting period.
	Restricted Performance Share Units Plan
	The Compensation Committee of the Parent Company’s Board of Trustees has granted performance share-based awards (referred to as Restricted Performance Share Units, or RPSUs) to officers of the Parent Company. The RPSUs are settled in common shares, with the number of common shares issuable in settlement determined based on the Company’s total shareholder return over specified measurement periods compared to total shareholder returns of comparative groups over the measurement periods. The table below presents certain information as to RPSU awards.
	Grant Date		Measurement Period Commencement Date	Measurement Period End Date		Fair Value of Units on Grant Date (in thousands)			Units Granted			Units Canceled		Units		Unvested Balance
														Vested (a)
	3/1/12		1/1/12	12/31/14		$	4,273		265,222			(38,959	)	(14,742	)	211,521
	2/25/13		1/1/13	12/31/15		4,137			231,093			(27,698	)			203,395
	3/11/14		1/1/14	12/31/16		2,624			134,284							134,284
	3/12/14		1/1/14	12/31/16		1,225			61,720							61,720
	(a) These RPSUs were settled upon the holder’s qualifying retirement in October 2012 after reaching age 57 and accumulating at least 15 years of service with the Company. Of the 14,742 RPSU's originally granted, 563 dividend equivalent rights were accrued at the time of qualifying retirement and the Company issued 30,610 shares in settlement of the RPSU's based on the Company’s total shareholder return-based performance achievement, as computed under the award agreement, on October 31, 2012 of 200%.
	The Company values each RPSU on its grant date using a Monte Carlo simulation. The fair values of each award are being amortized over the three year cliff vesting period. The vesting of RPSUs is subject to acceleration upon a change in control or if the recipient of the award were to die, become disabled or retire in a qualifying retirement prior to the vesting date. In accordance with the accounting standard for stock-based compensation, the Company amortizes stock-based compensation costs through the qualifying retirement date for those executives who meet the conditions for qualifying retirement during the schedule vesting period.
	For the three and six-month periods ended June 30, 2014, the Company recognized total compensation expense for the 2014, 2013 and 2012 RPSU awards of $0.5 million and $2.3 million, of which $0.2 million and 0.7 million, respectively, were capitalized consistent with the Company’s policies for capitalizing eligible portions of employee compensation. For the three and six-month periods ended June 30, 2013, the Company recognized total compensation expense for the 2013, 2012 and 2011 RPSU awards of $1.3 million and $2.5 million, of which $0.2 million and $0.4 million, respectively, were capitalized consistent with the Company’s policies for capitalizing eligible portions of employee compensation.
	A total of 150,829 common shares were issued on March 1, 2014 to holders in settlement of the RPSUs awarded on March 2, 2011 (with a three-year measurement period ended December 31, 2013). Holders of these RPSUs also received a cash dividend of $0.15 per share for these common shares on February 7, 2014.

Segment_Information

Segment Information	6 Months Ended
	Jun. 30, 2014
Segment Reporting [Abstract]	'
Segment Reporting Disclosure [Text Block]	'
	SEGMENT INFORMATION
	During the quarter ended June 30, 2014, the Company was managing its portfolio within seven segments: (1) Pennsylvania Suburbs, (2) Philadelphia Central Business District (CBD), (3) Metropolitan Washington, D.C., (4) New Jersey/Delaware, (5) Richmond, Virginia, (6) Austin, Texas and (7) California. The Pennsylvania Suburbs segment includes properties in Chester, Delaware, and Montgomery counties in the Philadelphia suburbs. The Philadelphia CBD segment includes properties located in the City of Philadelphia in Pennsylvania. The Metropolitan Washington, D.C. segment includes properties in Northern Virginia and southern Maryland. The New Jersey/Delaware segment includes properties in Burlington and Camden counties in New Jersey and in New Castle county in the state of Delaware. The Richmond, Virginia segment includes properties primarily in Albemarle, Chesterfield, Goochland and Henrico counties and one property in Durham, North Carolina. The Austin, Texas segment includes properties in the City of Austin, Texas. The California segment includes properties in Oakland, Concord and Carlsbad. The corporate group is responsible for cash and investment management, development of certain real estate properties during the construction period, and certain other general support functions.
	The following tables provide selected asset information and results of operations of the Company's reportable segments (in thousands):
	Real estate investments, at cost:
			30-Jun-14			31-Dec-13
	Philadelphia CBD		$	1,321,740		$	1,300,666
	Pennsylvania Suburbs		1,228,752			1,199,105
	Metropolitan Washington, D.C.		1,221,305			1,214,965
	New Jersey/Delaware		414,754			414,716
	Richmond,Virginia		310,751			310,397
	California		192,590			192,584
	Austin, Texas (a)		—			36,856
	Operating properties		$	4,689,892		$	4,669,289
	Corporate
	Construction-in-progress		$	92,713		$	74,174
	Land inventory		$	90,266		$	93,351
	(a)	On April 3, 2014, the Company contributed Four Points Centre to an unconsolidated joint venture. See Note 3 for further information on the contribution. Following the contribution, there are no wholly owned properties in the Austin, Texas segment.
	Net operating income:
		Three-month periods ended
		June 30,
		2014									2013
		Total revenue			Operating expenses (b)			Net operating income			Total revenue			Operating expenses (b)			Net operating income
	Philadelphia CBD	$	51,420		$	(18,789	)	$	32,631		$	36,142		$	(13,587	)	$	22,555
	Pennsylvania Suburbs	40,743			(13,742		)	27,001			37,002			(13,704		)	23,298
	Metropolitan Washington, D.C.	28,949			(10,505		)	18,444			28,783			(10,773		)	18,010
	New Jersey/Delaware	14,841			(7,531		)	7,310			15,024			(6,871		)	8,153
	Richmond, Virginia	8,322			(3,566		)	4,756			8,954			(3,599		)	5,355
	California	4,895			(2,515		)	2,380			4,536			(2,338		)	2,198
	Austin, Texas (a)	976			(617		)	359			9,872			(4,207		)	5,665
	Corporate	354			(442		)	(88		)	331			106			437
	Operating Properties	$	150,500		$	(57,707	)	$	92,793		$	140,644		$	(54,973	)	$	85,671
		Six-month periods ended
		June 30,
		2014									2013
		Total revenue			Operating expenses (b)			Net operating income			Total revenue			Operating expenses (b)			Net operating income
	Philadelphia CBD	$	100,834		$	(37,231	)	$	63,603		$	72,067		$	(27,121	)	$	44,946
	Pennsylvania Suburbs	81,317			(28,431		)	52,886			74,918			(28,310		)	46,608
	Metropolitan Washington, D.C.	59,639			(22,462		)	37,177			56,568			(21,536		)	35,032
	New Jersey/Delaware	30,466			(16,223		)	14,243			29,944			(13,902		)	16,042
	Richmond, Virginia	17,189			(7,906		)	9,283			17,719			(7,282		)	10,437
	California	9,497			(4,923		)	4,574			9,141			(4,498		)	4,643
	Austin, Texas (a)	3,057			(1,793		)	1,264			19,129			(8,165		)	10,964
	Corporate	615			(712		)	(97		)	712			772			1,484
	Operating Properties	$	302,614		$	(119,681	)	$	182,933		$	280,198		$	(110,042	)	$	170,156
	(a)	On On April 3, 2014, the Company contributed Four Points Centre to an unconsolidated real estate venture. See Note 3 for further information on the contribution. On October 16, 2013, seven properties in the Austin portfolio where contributed to an unconsolidated real estate venture. Following the contribution of these properties, there are no wholly owned properties in the Austin, Texas segment.
	(b)	Includes property operating expense, real estate taxes and third party management expense.
	Unconsolidated real estate ventures:
		Investment in real estate ventures, at equity						Equity in income (loss) of real estate ventures
		As of						Three-month periods ended June 30,						Six-month periods ended June 30,
		30-Jun-14			31-Dec-13			2014			2013			2014			2013
	Philadelphia CBD	$	20,689		$	19,975		$	—		$	577		$	(21	)	$	1,143
	Pennsylvania Suburbs	17,544			17,272			(391		)	558			(359		)	588
	Metropolitan Washington, D.C.	61,604			59,905			(42		)	(35		)	25			(19		)
	New Jersey/Delaware	—			—			103			167			122			1,075
	Richmond, Virginia	1,295			1,400			115			243			69			236
	Austin, Texas (a)	84,910			81,960			(274		)	(2		)	(83		)	20
	Total	$	186,042		$	180,512		$	(489	)	$	1,508		$	(247	)	$	3,043
	(a)	Investment in real estate ventures does not include the negative investment balance of one real estate venture totaling $1.2 million as of June 30, 2014, which is included in other liabilities.
	Net operating income (“NOI”) is an non-GAAP measure that is defined as total revenue less property operating expenses, real estate taxes and third party management expenses. Segment NOI includes revenue, real estate taxes and property operating expenses directly related to operation and management of the properties owned and managed within the respective geographical region. Segment NOI excludes property level depreciation and amortization, revenue and expenses directly associated with third party real estate management services, expenses associated with corporate administrative support services, and inter-company eliminations. NOI also does not reflect general and administrative expenses, interest expenses, real estate impairment losses, depreciation and amortization costs, capital expenditures and leasing costs. Trends in development and construction activities that could materially impact the Company’s results from operations are also not reflected in NOI. 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 also believes that NOI provides useful information to investors regarding its financial condition and results of operations because it reflects only those income and expenses recorded at the property level. The Company believes that net income, as defined by GAAP, is the most appropriate earnings measure. The following is a reconciliation of consolidated NOI to consolidated net income (loss), as defined by GAAP:
		Three-month periods ended June 30,						Six-month periods ended June 30,
		2014			2013			2014			2013
		(amounts in thousands)						(amounts in thousands)
	Consolidated net operating income	$	92,793		$	85,671		$	182,933		$	170,156
Other income (expense):
Depreciation and amortization	(52,587		)	(49,241		)	(105,157		)	(98,717		)
General and administrative expenses	(6,005		)	(7,336		)	(14,186		)	(13,887		)
Interest income	385			122			770			180
Interest expense	(31,512		)	(30,437		)	(63,356		)	(61,351		)
Amortization of deferred financing costs	(1,197		)	(1,183		)	(2,386		)	(2,344		)
Interest expense - financing obligation	(316		)	(211		)	(588		)	(429		)
Equity in income (loss) of real estate ventures	(489		)	1,508			(247		)	3,043
Gain (Loss) on sale of undepreciated real estate	(3		)	—			1,184			—
Gain from remeasurement of investment in a real estate venture	458			7,847			458			7,847
Gain (Loss) on real estate venture transactions	(282		)	3,683			(417		)	3,683
Loss on early extinguishment of debt	—			(1,113		)	—			(1,116		)
Loss from continuing operations	1,245			9,310			(992		)	7,065
Income (loss) from discontinued operations	929			(2,130		)	921			4,034
Net income (loss)	$	2,174		$	7,180		$	(71	)	$	11,099

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
COMMITMENTS AND CONTINGENCIES [Text Block]	'
	COMMITMENTS AND CONTINGENCIES
	Legal Proceedings
	The Company is involved from time to time in litigation on various matters, including disputes with tenants 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 we determine that the likelihood of an unfavorable outcome is probable and when the amount of loss is reasonably estimable. The Company does not expect that the liabilities, if any, that may ultimately result from such legal actions will have a material adverse effect on the consolidated financial position, results of operations or cash flows of the Company.
	Environmental
	As an owner of real estate, the Company is subject to various environmental laws of federal, state, and local governments. The Company’s compliance with existing laws has not had a material adverse effect on its financial condition and results of operations, and the Company does not believe it will have a material adverse effect in the future. However, the Company cannot predict the impact of unforeseen environmental contingencies or new or changed laws or regulations on its current Properties or on properties that the Company may acquire.
	Ground Rent
	Future minimum rental payments under the terms of all non-cancelable ground leases under which the Company is the lessee are expensed on a straight-line basis regardless of when payments are due. The Company’s ground leases have remaining lease terms ranging from 7 to 75 years. Minimum future rental payments on non-cancelable leases at June 30, 2014 are as follows (in thousands):
	2014 (six months remaining)	$	690
	2015	1,380
	2016	1,380
	2017	1,380
	2018	1,380
	Thereafter	58,516
	Total	$	64,726
	The Company obtained ground tenancy rights related to two 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, 2013 for further detail regarding commitments and contingencies.

Subsequent_Events

Subsequent Events	6 Months Ended
	Jun. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events [Text Block]	'
	SUBSEQUENT EVENTS
	The Company has evaluated subsequent events through the date the financial statements were issued.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Basis of Accounting, Policy [Policy Text Block]	'
	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 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 June 30, 2014, the results of its operations for the three and six-month periods ended June 30, 2014 and 2013 and its cash flows for the six-month periods ended June 30, 2014 and 2013 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 2013 Annual Report on Form 10-K filed with the SEC on February 25, 2014.
Reclassification, Policy [Policy Text Block]	'
	Reclassifications
	Certain amounts have been reclassified in prior years to conform to the current year presentation, including the reclassification of notes receivable to other assets within the balance sheets and the reclassification of changes in escrow balances from operating cash flows to investing cash flows in the statements of cash flows. All other reclassifications are related to the treatment of sold properties as discontinued operations on the statement of operations for all periods presented. See Recent Accounting Pronouncements below for revisions to the accounting guidance for discontinued operations.
Recent Accounting Pronouncement [Policy Text Block]	'
	Recent Accounting Pronouncements
	In May 2014 the Financial Accounting Standards Board (FASB) issued guidance requiring revenue to be recognized in an amount that reflects the consideration expected to be received in exchange for those goods and services. The guidance requires the disclosure of sufficient quantitative and qualitative information for financial statement users to understand the nature, amount, timing and uncertainty of revenue and associated cash flows arising from contracts with customers. The guidance is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period, with early adoption precluded. The Company has not yet determined the impact, if any, that the adoption of this guidance will have on its consolidated financial position or results of operations.
	In April 2014 the FASB issued revised guidance on discontinued operations and disclosures of disposals of components of an entity. The update revises the definition to include only disposals involving a strategic shift that has a major effect on the entity’s operations and financial results when the disposal asset or group meets the existing criterion for treatment as held for sale. Examples of a strategic shift include the withdrawal from a major geographic area, line of business, equity method investment or any other major parts of a business, as applicable. A component of the entity comprises operations and cash flows that can be clearly distinguished, operationally and for financial reporting purposes, from the rest of the entity. In addition, the revised standard no longer precludes presentation as a discontinued operation if there are operations and cash flows of the component that have not been eliminated from the reporting entity’s ongoing operations, or if there is significant continuing involvement with a component after its disposal.
	The amendments require additional disclosures about discontinued operations including; the major classes of net income or loss where net income is otherwise presented, the operating and investing cash flows of discontinued operations where net income is otherwise presented, depreciation, amortization, capital expenditures and significant operating and investing non-cash items of the discontinued operation for the periods in which net income is otherwise presented and, if there is a non-controlling interest, the related allocation to the parent company.
	Application is prospective, and required for periods beginning on or after December 15, 2014. This update should not be applied to assets classified as held for sale before the effective date even if the component of an entity is disposed of after the effective date. Early adoption is permitted for disposals or assets held for sale that have not been reported in the financial statements previously issued or available for issuance. The Company has elected to early adopt this standard as of January 1, 2014. All properties sold or determined held for sale prior to January 1, 2014 are classified as discontinued operations for all periods presented.

Real_Estate_Investments_Tables

Real Estate Investments (Tables)	6 Months Ended
	Jun. 30, 2014
Real Estate [Abstract]	'
Gross Carrying Value Of Company's Properties [Table Text Block]	'
	As of June 30, 2014 and December 31, 2013, the gross carrying value of the Company’s Properties was as follows (in thousands):
		June 30,		December 31,
		2014		2013
	Land	$	688,775	$	680,513
	Building and improvements	3,479,850		3,504,060
	Tenant improvements	521,267		484,716
		$	4,689,892	$	4,669,289

Investment_in_Unconsolidated_V1

Investment in Unconsolidated Ventures (Tables)	6 Months Ended
	Jun. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Equity Method Investment Summarized Financial Information [Table Text Block]	'
	The following is a summary of the financial position of the Real Estate Ventures as of June 30, 2014 and December 31, 2013 (in thousands):
		June 30,				December 31,
		2014				2013
	Net property	$	1,081,064			$	965,475
	Other assets	153,348				164,152
	Other liabilities	68,031				49,442
	Debt	792,919				699,860
	Equity	373,462				380,325
	Company’s share of equity (Company’s basis) (a)	186,042			(b)	180,512
	(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.
	(b) Does not include the negative investment balance of one real estate venture totaling $1.2 million as of June 30, 2014, which is included in other liabilities.
Summary of results of operations of unconsolidated Real Estate Venture [Table Text Block]	'
	The following is a summary of results of operations of the Real Estate Ventures in which the Company had interests during these periods (in thousands):
		Three-month periods ended June 30,							Six-month periods ended June 30,
		2014				2013			2014			2013
	Revenue	$	35,074			$	36,927		$	69,459		$	77,816
	Operating expenses	14,842				17,205			28,824			35,472
	Interest expense, net	8,889				9,173			16,989			18,944
	Depreciation and amortization	13,273				10,979			26,871			23,885
	Net loss	(1,930		)		(430		)	(3,225		)	(485		)
	Company’s share of income (loss) (Company’s basis)	(489		)		1,508			(247		)	3,043

Deferred_Costs_Tables

Deferred Costs (Tables)	6 Months Ended
	Jun. 30, 2014
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]	'
Components Of Deferred Costs Net [Table Text Block]	'
	As of June 30, 2014 and December 31, 2013, the Company’s deferred costs were comprised of the following (in thousands):
		June 30, 2014
		Total Cost		Accumulated			Deferred Costs,
				Amortization			net
	Leasing Costs	$	161,800	$	(61,694	)	$	100,106
	Financing Costs	40,315		(16,829		)	23,486
	Total	$	202,115	$	(78,523	)	$	123,592
		December 31, 2013
		Total Cost		Accumulated			Deferred Costs,
				Amortization			net
	Leasing Costs	$	155,885	$	(58,805	)	$	97,080
	Financing Costs	40,317		(14,443		)	25,874
	Total	$	196,202	$	(73,248	)	$	122,954

Intangible_Assets_Tables

Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Intangible Assets [Table Text Block]	'
	As of June 30, 2014 and December 31, 2013, the Company’s intangible assets/liabilities were comprised of the following (in thousands):
		June 30, 2014
		Total Cost		Accumulated			Intangible assets/liabilities, net
				Amortization
	Intangible assets, net:
	In-place lease value	$	136,388	$	(38,767	)	$	97,621
	Tenant relationship value	37,019		(27,159		)	9,860
	Above market leases acquired	6,120		(1,461		)	4,659
	Total intangible assets, net	$	179,527	$	(67,387	)	$	112,140
	Acquired lease intangibles, net:
	Below market leases acquired	$	64,679	$	(35,563	)	$	29,116
		December 31, 2013
		Total Cost		Accumulated			Intangible assets/liabilities, net
				Amortization
	Intangible assets, net:
	In-place lease value	$	150,782	$	(35,607	)	$	115,175
	Tenant relationship value	38,692		(26,868		)	11,824
	Above market leases acquired	6,673		(1,343		)	5,330
	Total intangible assets, net	$	196,147	$	(63,818	)	$	132,329
	Acquired lease intangibles, net:
	Below market leases acquired	$	81,991	$	(47,547	)	$	34,444
Annual Amortization For Its Intangible Assets Liabilities [Table Text Block]	'
	As of June 30, 2014, the Company’s annual amortization for its intangible assets/liabilities were as follows (in thousands, and assuming no prospective early lease terminations):
		Assets		Liabilities
	2014 (six months remaining)	$	12,075	$	3,093
	2015	21,581		5,223
	2016	17,102		3,254
	2017	15,279		2,664
	2018	11,458		2,241
	Thereafter	34,645		12,641
	Total	$	112,140	$	29,116

Debt_Obligations_Tables

Debt Obligations (Tables)	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Consolidated Debt Obligations [Table Text Block]	'
	The following table sets forth information regarding the Company’s consolidated debt obligations at June 30, 2014 and December 31, 2013 (in thousands):
	Property / Location	June 30, 2014			31-Dec-13			Effective			Maturity
								Interest			Date
								Rate
	MORTGAGE DEBT:
	Tysons Corner	$	90,460		$	91,395		5.36	%	(a)	Aug-15
	One Commerce Square	124,151			125,089			3.68	%	(a)	Jan-16
	Two Logan Square	88,174			88,583			7.57	%		Apr-16
	Fairview Eleven Tower	21,470			21,630			4.25	%	(b)	Jan-17
	Two Commerce Square	112,000			112,000			4.51	%	(a)	Apr-23
	Cira Square (GSA Philadelphia Campus)	187,751			190,964			7	%		Sep-30
	Cira Centre South Garage	38,950			40,101			7.12	%		Sep-30
	Principal balance outstanding	662,956			669,762
	Plus: fair market value premiums (discounts), net	(478		)	389
	Total mortgage indebtedness	$	662,478		$	670,151
	UNSECURED DEBT:
	Three-Year Term Loan - Swapped to fixed	$	150,000		$	150,000		2.6	%		Feb-15
	Four-Year Term Loan	100,000			100,000			LIBOR + 1.75%		(c)	Feb-16
	Seven-Year Term Loan - Swapped to fixed	200,000			200,000			3.62	%		Feb-19
	$250.0M 5.400% Guaranteed Notes due 2014	218,549			218,549			5.53	%		Nov-14
	$250.0M 7.500% Guaranteed Notes due 2015	157,625			157,625			7.76	%		May-15
	$250.0M 6.000% Guaranteed Notes due 2016	149,919			149,919			5.95	%		Apr-16
	$300.0M 5.700% Guaranteed Notes due 2017	300,000			300,000			5.68	%		May-17
	$325.0M 4.950% Guaranteed Notes due 2018	325,000			325,000			5.13	%		Apr-18
	$250.0M 3.950% Guaranteed Notes due 2023	250,000			250,000			4.02	%		Feb-23
	Indenture IA (Preferred Trust I)	27,062			27,062			2.75	%		Mar-35
	Indenture IB (Preferred Trust I)	25,774			25,774			3.3	%		Apr-35
	Indenture II (Preferred Trust II)	25,774			25,774			3.09	%		Jul-35
	Principal balance outstanding	1,929,703			1,929,703
	Plus: original issue premiums (discounts), net	(3,931		)	(4,473		)
	Total unsecured indebtedness	$	1,925,772		$	1,925,230
	Total Debt Obligations	$	2,588,250		$	2,595,381
	(a)	These loans were assumed upon acquisition of the related properties. The interest rate reflects the market rate at the time of acquisition.
	(b)	Represents the full debt amount secured by a property owned by a consolidated real estate venture in which the Company holds a 50% interest.
	(c)	London Interbank Offered Rate (“LIBOR”).
Schedule of Maturities of Long-term Debt [Table Text Block]	'
	As of June 30, 2014, the Company’s aggregate scheduled principal payments on debt obligations, excluding amortization of discounts and premiums, were as follows (in thousands):
	2014 (six months remaining)	$	225,570
	2015	409,655
	2016	467,703
	2017	330,323
	2018	336,954
	Thereafter	822,454
	Total principal payments	2,592,659
	Net unamortized premiums/(discounts)	(4,409		)
	Outstanding indebtedness	$	2,588,250

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Schedule Of Financial Instruments With Fair Values Different From Their Carrying Amount [Table Text Block]	'
	The following are financial instruments for which the Company’s estimates of fair value differ from the carrying amounts (in thousands):
		June 30, 2014				December 31, 2013
		Carrying		Fair		Carrying		Fair
		Amount		Value		Amount		Value
	Unsecured notes payable	$	1,397,162	$	1,478,767	$	1,396,620	$	1,471,041
	Variable rate debt	$	528,610	$	504,044	$	528,610	$	526,693
	Mortgage notes payable	$	662,478	$	697,731	$	670,151	$	715,244
	Notes receivable	$	4,226	$	5,088	$	7,026	$	7,759

Risk_Management_and_Use_of_Fin1

Risk Management and Use of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2014
Derivatives, Fair Value [Line Items]	'
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]	'
	Hedge Product	Hedge Type	Designation		Notional Amount				Strike		Trade Date	Maturity Date	Fair value
					6/30/14		12/31/13						6/30/14			12/31/13
	Assets (Liabilities):
	Swap	Interest Rate	Cash Flow	(a)	$	200,000	$	200,000	3.623	%	December 6-13, 2011	February 1, 2019	$	(2,843	)	$	(545	)
	Swap	Interest Rate	Cash Flow	(a)	77,000		77,000		2.703	%	December 9-13, 2011	February 1, 2016	(799		)	(887		)
	Swap	Interest Rate	Cash Flow	(a)	50,000		50,000		2.47	%	December 13, 2011	February 1, 2015	(191		)	(283		)
	Swap	Interest Rate	Cash Flow	(a)	27,062		27,062		2.75	%	December 21, 2011	September 30, 2017	(385		)	(311		)
	Swap	Interest Rate	Cash Flow	(a)	25,774		25,774		3.3	%	December 22, 2011	January 30, 2021	(128		)	549
	Swap	Interest Rate	Cash Flow	(a)	25,774		25,774		3.09	%	6-Jan-12	30-Oct-19	(214		)	218
	Swap	Interest Rate	Cash Flow	(a)	23,000		23,000		2.513	%	December 7-12, 2011	May 1, 2015	(125		)	(162		)
					$	428,610	$	428,610					$	(4,685	)	$	(1,421	)
	(a) Hedging unsecured variable rate debt.

Discontinued_Operations_Tables

Discontinued Operations (Tables)	6 Months Ended
	Jun. 30, 2014
Long Lived Assets Held-for-sale [Line Items]	'
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block]	'
	For the three and six-month periods ended June 30, 2013, income from discontinued operations relates to the 14 properties sold by the Company from January 1, 2013 through December 31, 2013. The following table summarizes the revenue and expense information for properties classified as discontinued operations for the three and six-month periods ended June 30, 2013 (in thousands):
		Three-month period ended June 30, 2013			Six-month period ended
					30-Jun-13
	Revenue:
	Rents	$	895		$	4,658
	Tenant reimbursements	7			345
	Termination fees	—			—
	Other	9			123
	Total revenue	911			5,126
	Expenses:
	Property operating expenses	330			1,711
	Real estate taxes	118			584
	Depreciation and amortization	337			1,845
	Total operating expenses	785			4,140
	Other income:
	Interest income	3			3
	Income from discontinued operations before gain on sale of interests in real estate	129			989
	Net gain on disposition of discontinued operations	(2,259		)	3,045
	Income from discontinued operations	$	(2,130	)	$	4,034

Beneficiaries_Equity_of_the_Pa1

Beneficiaries Equity of the Parent Company (Tables)	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Earnings Per Share (EPS), Basic and Diluted	'
	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 June 30,
		2014						2013
		Basic			Diluted			Basic			Diluted
	Numerator
	Income from continuing operations	$	1,245		$	1,245		$	9,310		$	9,310
	Income (loss) from continuing operations attributable to non-controlling interests	5			5			(87		)	(87		)
	Net loss attributable to non-controlling interest — partners' share of consolidated real estate ventures	24			24			—			—
	Nonforfeitable dividends allocated to unvested restricted shareholders	(83		)	(83		)	(85		)	(85		)
	Preferred share dividends	(1,725		)	(1,725		)	(1,725		)	(1,725		)
	Income (loss) from continuing operations available to common shareholders	(534		)	(534		)	7,413			7,413
	Income (loss) from discontinued operations	929			929			(2,130		)	(2,130		)
	Discontinued operations attributable to non-controlling interests	(10		)	(10		)	25			25
	Discontinued operations attributable to common shareholders	919			919			(2,105		)	(2,105		)
	Net income attributable to common shareholders	$	385		$	385		$	5,308		$	5,308
	Denominator
	Weighted-average shares outstanding	157,037,348			157,037,348			155,347,384			155,347,384
	Contingent securities/Share based compensation	—			—			—			1,343,817
	Weighted-average shares outstanding	157,037,348			157,037,348			155,347,384			156,691,201
	Earnings per Common Share:
	Income from continuing operations attributable to common shareholders	$	—		$	—		$	0.05		$	0.05
	Discontinued operations attributable to common shareholders	—			—			(0.02		)	(0.02		)
	Net income attributable to common shareholders	$	—		$	—		$	0.03		$	0.03

Partners_Equity_of_the_Operati1

Partners Equity of the Operating Partnership (Tables)	6 Months Ended
	Jun. 30, 2014
Equity [Abstract]	'
Earnings Per Common Partnership Unit [Table Text Block]	'
	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 June 30,
		2014						2013
		Basic			Diluted			Basic			Diluted
	Numerator
	Income from continuing operations	$	1,245		$	1,245		$	9,310		$	9,310
	Nonforfeitable dividends allocated to unvested restricted unitholders	(83		)	(83		)	(85		)	(85		)
	Preferred unit dividends	(1,725		)	(1,725		)	(1,725		)	(1,725		)
	Net income attributable to non-controlling interests	24			24			—			—
	Income (loss) from continuing operations available to common unitholders	(539		)	(539		)	7,500			7,500
	Discontinued operations attributable to common unitholders	929			929			(2,130		)	(2,130		)
	Net income attributable to common unitholders	$	390		$	390		$	5,370		$	5,370
	Denominator
	Weighted-average units outstanding	158,801,087			158,801,087			157,131,697			157,131,697
	Contingent securities/Share based compensation	—			—			—			1,343,817
	Total weighted-average units outstanding	158,801,087			158,801,087			157,131,697			158,475,514
	Earnings per Common Partnership Unit:
	Income from continuing operations attributable to common unitholders	$	—		$	—		$	0.05		$	0.05
	Discontinued operations attributable to common unitholders	—			—			(0.02		)	(0.02		)
	Net income attributable to common unitholders	$	—		$	—		$	0.03		$	0.03
		Six-month periods ended June 30,
		2014						2013
		Basic			Diluted			Basic			Diluted
	Numerator
	Income (loss) from continuing operations	$	(992	)	$	(992	)	$	7,065		$	7,065
	Amount allocable to unvested restricted unitholders	(186		)	(186		)	(193		)	(193		)
	Preferred unit dividends	(3,450		)	(3,450		)	(3,450		)	(3,450		)
	Net income attributable to non-controlling interests	12			12			—			—
	Income (loss) from continuing operations available to common unitholders	(4,616		)	(4,616		)	3,422			3,422
	Discontinued operations attributable to common unitholders	921			921			4,034			4,034
	Net income (loss) attributable to common unitholders	$	(3,695	)	$	(3,695	)	$	7,456		$	7,456
	Denominator
	Weighted-average units outstanding	158,680,095			158,680,095			151,323,813			151,323,813
	Contingent securities/Share based compensation	—			—			—			1,157,288
	Total weighted-average units outstanding	158,680,095			158,680,095			151,323,813			152,481,101
	Earnings per Common Partnership Unit:
	Income (loss) from continuing operations attributable to common unitholders	$	(0.03	)	$	(0.03	)	$	0.02		$	0.02
	Discontinued operations attributable to common unitholders	0.01			0.01			0.03			0.03
	Net income (loss) attributable to common unitholders	$	(0.02	)	$	(0.02	)	$	0.05		$	0.05

Share_Based_and_Deferred_Compe1

Share Based and Deferred Compensation (Tables)	6 Months Ended
	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Options Activity [Table Text Block]	'
	Option activity as of June 30, 2014 and changes during the six months ended June 30, 2014 were as follows:
		Shares		Weighted				Weighted Average		Aggregate Intrinsic
				Average				Remaining Contractual		Value
				Exercise Price				Term (in years)
	Outstanding at January 1, 2014	2,983,569		$	15.5			5.15		$	—
	Granted	—		$	—			—		—
	Exercised	(60,127	)	$	11.8			—		$	182,101
	Canceled	(114,658	)	$	20.61
	Outstanding at June 30, 2014	2,808,784		$	15.37			4.67		$	632,239
	Vested/Exercisable at June 30, 2014	2,808,784		$	15.37			4.67		$	632,239
Company's Restricted Share Activity [Table Text Block]	'
	The following table summarizes the Company’s restricted share activity for the six months ended June 30, 2014:
		Shares		Weighted
				Average Grant
				Date Fair value
	Non-vested at January 1, 2014	563,713		$	12.56
	Granted	229,119		14.47
	Vested	(234,169	)	13.44
	Forfeited	(8,441	)	12.36
	Non-vested at June 30, 2014	550,222		$	12.22
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]	'
	Grant Date		Measurement Period Commencement Date	Measurement Period End Date		Fair Value of Units on Grant Date (in thousands)			Units Granted			Units Canceled		Units		Unvested Balance
														Vested (a)
	3/1/12		1/1/12	12/31/14		$	4,273		265,222			(38,959	)	(14,742	)	211,521
	2/25/13		1/1/13	12/31/15		4,137			231,093			(27,698	)			203,395
	3/11/14		1/1/14	12/31/16		2,624			134,284							134,284
	3/12/14		1/1/14	12/31/16		1,225			61,720							61,720
	(a) These RPSUs were settled upon the holder’s qualifying retirement in October 2012 after reaching age 57 and accumulating at least 15 years of service with the Company. Of the 14,742 RPSU's originally granted, 563 dividend equivalent rights were accrued at the time of qualifying retirement and the Company issued 30,610 shares in settlement of the RPSU's based on the Company’s total shareholder return-based performance achievement, as computed under the award agreement, on October 31, 2012 of 200%.

Segment_Information_Tables

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2014
Segment Reporting [Abstract]	'
Schedule of Segment Real Estate Investments, by Segment [Table Text Block]	'
	Real estate investments, at cost:
			30-Jun-14			31-Dec-13
	Philadelphia CBD		$	1,321,740		$	1,300,666
	Pennsylvania Suburbs		1,228,752			1,199,105
	Metropolitan Washington, D.C.		1,221,305			1,214,965
	New Jersey/Delaware		414,754			414,716
	Richmond,Virginia		310,751			310,397
	California		192,590			192,584
	Austin, Texas (a)		—			36,856
	Operating properties		$	4,689,892		$	4,669,289
	Corporate
	Construction-in-progress		$	92,713		$	74,174
	Land inventory		$	90,266		$	93,351
Schedule of Segment Net Operating Income, by Segment [Table Text Block]	'
	Net operating income:
		Three-month periods ended
		June 30,
		2014									2013
		Total revenue			Operating expenses (b)			Net operating income			Total revenue			Operating expenses (b)			Net operating income
	Philadelphia CBD	$	51,420		$	(18,789	)	$	32,631		$	36,142		$	(13,587	)	$	22,555
	Pennsylvania Suburbs	40,743			(13,742		)	27,001			37,002			(13,704		)	23,298
	Metropolitan Washington, D.C.	28,949			(10,505		)	18,444			28,783			(10,773		)	18,010
	New Jersey/Delaware	14,841			(7,531		)	7,310			15,024			(6,871		)	8,153
	Richmond, Virginia	8,322			(3,566		)	4,756			8,954			(3,599		)	5,355
	California	4,895			(2,515		)	2,380			4,536			(2,338		)	2,198
	Austin, Texas (a)	976			(617		)	359			9,872			(4,207		)	5,665
	Corporate	354			(442		)	(88		)	331			106			437
	Operating Properties	$	150,500		$	(57,707	)	$	92,793		$	140,644		$	(54,973	)	$	85,671
		Six-month periods ended
		June 30,
		2014									2013
		Total revenue			Operating expenses (b)			Net operating income			Total revenue			Operating expenses (b)			Net operating income
	Philadelphia CBD	$	100,834		$	(37,231	)	$	63,603		$	72,067		$	(27,121	)	$	44,946
	Pennsylvania Suburbs	81,317			(28,431		)	52,886			74,918			(28,310		)	46,608
	Metropolitan Washington, D.C.	59,639			(22,462		)	37,177			56,568			(21,536		)	35,032
	New Jersey/Delaware	30,466			(16,223		)	14,243			29,944			(13,902		)	16,042
	Richmond, Virginia	17,189			(7,906		)	9,283			17,719			(7,282		)	10,437
	California	9,497			(4,923		)	4,574			9,141			(4,498		)	4,643
	Austin, Texas (a)	3,057			(1,793		)	1,264			19,129			(8,165		)	10,964
	Corporate	615			(712		)	(97		)	712			772			1,484
	Operating Properties	$	302,614		$	(119,681	)	$	182,933		$	280,198		$	(110,042	)	$	170,156
	(a)	On On April 3, 2014, the Company contributed Four Points Centre to an unconsolidated real estate venture. See Note 3 for further information on the contribution. On October 16, 2013, seven properties in the Austin portfolio where contributed to an unconsolidated real estate venture. Following the contribution of these properties, there are no wholly owned properties in the Austin, Texas segment.
	(b)	Includes property operating expense, real estate taxes and third party management expense.
Schedule of Segment Reporting Information, by Segment [Table Text Block]	'
	Unconsolidated real estate ventures:
		Investment in real estate ventures, at equity						Equity in income (loss) of real estate ventures
		As of						Three-month periods ended June 30,						Six-month periods ended June 30,
		30-Jun-14			31-Dec-13			2014			2013			2014			2013
	Philadelphia CBD	$	20,689		$	19,975		$	—		$	577		$	(21	)	$	1,143
	Pennsylvania Suburbs	17,544			17,272			(391		)	558			(359		)	588
	Metropolitan Washington, D.C.	61,604			59,905			(42		)	(35		)	25			(19		)
	New Jersey/Delaware	—			—			103			167			122			1,075
	Richmond, Virginia	1,295			1,400			115			243			69			236
	Austin, Texas (a)	84,910			81,960			(274		)	(2		)	(83		)	20
	Total	$	186,042		$	180,512		$	(489	)	$	1,508		$	(247	)	$	3,043
Reconciliation Of Consolidated Net Operating Income [Table Text Block]	'
	(a)	Investment in real estate ventures does not include the negative investment balance of one real estate venture totaling $1.2 million as of June 30, 2014, which is included in other liabilities.
	Net operating income (“NOI”) is an non-GAAP measure that is defined as total revenue less property operating expenses, real estate taxes and third party management expenses. Segment NOI includes revenue, real estate taxes and property operating expenses directly related to operation and management of the properties owned and managed within the respective geographical region. Segment NOI excludes property level depreciation and amortization, revenue and expenses directly associated with third party real estate management services, expenses associated with corporate administrative support services, and inter-company eliminations. NOI also does not reflect general and administrative expenses, interest expenses, real estate impairment losses, depreciation and amortization costs, capital expenditures and leasing costs. Trends in development and construction activities that could materially impact the Company’s results from operations are also not reflected in NOI. 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 also believes that NOI provides useful information to investors regarding its financial condition and results of operations because it reflects only those income and expenses recorded at the property level. The Company believes that net income, as defined by GAAP, is the most appropriate earnings measure. The following is a reconciliation of consolidated NOI to consolidated net income (loss), as defined by GAAP:
		Three-month periods ended June 30,						Six-month periods ended June 30,
		2014			2013			2014			2013
		(amounts in thousands)						(amounts in thousands)
	Consolidated net operating income	$	92,793		$	85,671		$	182,933		$	170,156
	Other income (expense):
	Depreciation and amortization	(52,587		)	(49,241		)	(105,157		)	(98,717		)
	General and administrative expenses	(6,005		)	(7,336		)	(14,186		)	(13,887		)
	Interest income	385			122			770			180
	Interest expense	(31,512		)	(30,437		)	(63,356		)	(61,351		)
	Amortization of deferred financing costs	(1,197		)	(1,183		)	(2,386		)	(2,344		)
	Interest expense - financing obligation	(316		)	(211		)	(588		)	(429		)
	Equity in income (loss) of real estate ventures	(489		)	1,508			(247		)	3,043
	Gain (Loss) on sale of undepreciated real estate	(3		)	—			1,184			—
	Gain from remeasurement of investment in a real estate venture	458			7,847			458			7,847
	Gain (Loss) on real estate venture transactions	(282		)	3,683			(417		)	3,683
	Loss on early extinguishment of debt	—			(1,113		)	—			(1,116		)
	Loss from continuing operations	1,245			9,310			(992		)	7,065
	Income (loss) from discontinued operations	929			(2,130		)	921			4,034
	Net income (loss)	$	2,174		$	7,180		$	(71	)	$	11,099

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Operating Leases Future Minimum Payments Due [Table Text Block]	'
	Ground Rent
	Future minimum rental payments under the terms of all non-cancelable ground leases under which the Company is the lessee are expensed on a straight-line basis regardless of when payments are due. The Company’s ground leases have remaining lease terms ranging from 7 to 75 years. Minimum future rental payments on non-cancelable leases at June 30, 2014 are as follows (in thousands):
	2014 (six months remaining)	$	690
	2015	1,380
	2016	1,380
	2017	1,380
	2018	1,380
	Thereafter	58,516
	Total	$	64,726

Organization_of_the_Parent_Com1

Organization of the Parent Company and The Operating Partnership (Details)	Jun. 30, 2014	Jun. 30, 2013
	sqft	sqft
	Real_Estate_Investments
Parent Company [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Ownership in the Operating Partnership	98.90%	'
Net rentable square feet	25,400,000	'
Area Owned by Company of Undeveloped Parcels Of Land	419	'
Area Of Additional Undeveloped Parcels Of Land With Option to Purchase	50	'
Total potential development capacity	5,900,000	'
Unconsolidated Real Estate Ventures [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Net rentable square feet	5,900,000	6,200,000
Number Of Unconsolidated Real Estate Ventures	17	'
Wholly-owned Management Company Subsidiaries [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Net rentable square feet	33,500,000	'
Third Parties and Real Estate Ventures [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Net rentable square feet	8,100,000	'
Total Properties [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Number of Real Estate Properties	205	'
Office Properties [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Number of Real Estate Properties	175	'
Industrial Facilities [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Number of Real Estate Properties	20	'
Mixed Use Properties [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Number of Real Estate Properties	5	'
Retail Properties [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Number of Real Estate Properties	1	'
Core Properties [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Number of Real Estate Properties	201	'
Development Property [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Number of Real Estate Properties	2	'
Redevelopment Property [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Number of Real Estate Properties	1	'
Re-entitlement Property [Member]	'	'
Organization of The Parent Company and The Operating Partnership [Line Items]	'	'
Number of Real Estate Properties	1	'

Real_Estate_Investments_Gross_

Real Estate Investments Gross Carrying Value of Company's Properties (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment, Gross [Abstract]	'	'
Land	$688,775	$680,513
Buildings and Improvements, Gross	3,479,850	3,504,060
Leasehold Improvements, Gross	521,267	484,716
Real Estate Investments	$4,689,892	$4,669,289

Real_Estate_Investments_Acquis

Real Estate Investments Acquisitions and Dispositions (Details) (USD $)

3 Months Ended

6 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

0 Months Ended

6 Months Ended

0 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

Apr. 16, 2014

Apr. 07, 2014

Feb. 25, 2014

Feb. 25, 2013

Apr. 03, 2014

Mar. 27, 2014

Apr. 03, 2014

Feb. 19, 2014

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Dec. 19, 2013

Apr. 03, 2014

Apr. 03, 2014

West Point II Land [Member]

Princeton Pike Corporate Center [Member]

Princeton Pike Corporate Center [Member]

Princeton Pike Corporate Center [Member]

Four Points Centre [Member]

Rob Roy - Land [Member]

Austin Joint Venture [Member]

Encino Trace - Land [Member]

Encino Trace - Building I [Member]

One and Two Commerce Square [Member]

One and Two Commerce Square [Member]

One and Two Commerce Square [Member]

DRA Advisors LLC [Member]

Brandywine Realty Trust [Member]

acre

sqft

Properties

acre

Four Points Centre [Member]

sqft

Storey

Austin Joint Venture [Member]

Austin Joint Venture [Member]

Properties

sqft

acre

Four Points Centre [Member]

Four Points Centre [Member]

Storey

Properties

Storey

Significant Acquisitions and Disposals [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate gross sales price of a joint venture

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$41,500,000

Gain from remeasurement of investment in real estate ventures

458,000

7,847,000

458,000

7,847,000

'

'

'

'

'

'

'

'

'

'

500,000

'

'

'

'

Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25.00%

'

'

Business Combination, Step Acquisition, Equity Interest in Acquiree, Including Subsequent Acquisition, Percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

99.00%

'

'

Area Owned by Company of Undeveloped Parcels Of Land

'

'

'

'

'

'

'

'

'

'

'

'

54.1

'

'

'

'

'

'

Total potential development capacity

'

'

'

'

'

'

'

'

'

'

'

'

320,000

'

'

'

'

'

'

Number of Real Estate Properties

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

Number of floors of a building

'

'

'

'

'

'

'

'

'

3

'

'

4

'

'

'

41

'

'

Business Acquisition, Transaction Costs

'

'

'

'

'

'

'

'

2,000,000

'

'

'

'

'

'

'

'

'

'

Net Rentable Space

'

'

'

'

'

'

'

'

'

192,396

'

'

'

'

'

'

'

'

'

Accounts receivable, net

21,622,000

'

21,622,000

'

17,389,000

'

'

'

'

'

'

'

'

'

2,100,000

1,600,000

'

'

'

Area of Land

'

'

'

'

'

5.3

'

'

'

'

16.8

'

'

'

'

'

'

'

'

Business Combination, Consideration Transferred

'

'

'

'

'

'

'

'

'

'

'

'

14,000,000

'

'

'

'

'

'

Construction in Progress, Gross

'

'

'

'

'

'

'

'

'

'

'

'

8,400,000

18,700,000

'

'

'

'

'

Land

688,775,000

'

688,775,000

'

680,513,000

'

'

'

'

'

'

'

4,600,000

'

'

'

'

'

'

Number of real estate properties sold

'

'

'

'

'

'

'

'

8

'

'

'

'

'

'

'

'

'

'

Net Rentable Space Sold

'

'

'

'

'

'

'

'

800,546

'

'

'

'

'

'

'

'

'

'

Escrow Deposit

'

'

'

'

'

'

'

'

'

'

'

'

1,000,000

'

'

'

'

'

'

Land Sales

'

'

'

'

'

1,600,000

'

'

121,000,000

'

3,500,000

'

'

'

'

'

'

'

'

Net gain (loss) on disposition of discontinued operations

903,000

-2,259,000

903,000

3,045,000

'

'

900,000

5,300,000

'

'

'

'

'

'

'

'

'

'

'

Number of Real Estate Properties

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

Gain (Loss) on sale of undepreciated real estate

-3,000

0

1,184,000

0

'

'

'

'

'

'

1,200,000

'

'

'

'

'

'

'

'

Non-Recourse Debt

'

'

'

'

'

'

'

'

'

'

'

29,000,000

'

'

'

'

'

'

'

Amount Of Participant Contribution

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,900,000

'

Proceeds from Equity Method Investment, Dividends or Distributions

'

'

5,329,000

3,445,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

34,400,000

Equity method investment, credit to capital contribution

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,900,000

Gain (loss) on real estate venture transactions

($282,000)

$3,683,000

($417,000)

$3,683,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

($200,000)

Investment_in_Unconsolidated_V2

Investment in Unconsolidated Ventures (Narrative) (Details) (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2014	Apr. 03, 2014
	acre	Real_Estate_Ventures		Austin Joint Venture [Member]	TB-BDN Plymouth Apartments [Member]	Unconsolidated Real Estate Ventures [Member]	Unconsolidated Real Estate Ventures [Member]	The Grove at Cira Centre South [Member]	PJP VII [Member]	Four Points Centre [Member]
	Room					sqft	sqft			Storey
	Buildings									Properties
	sqft									sqft
	Real_Estate_Ventures
Schedule of Equity Method Investments [Line Items]	'	'	'	'	'	'	'	'	'	'
Number of floors of a building	'	'	'	'	'	'	'	'	'	3
Company's share of equity (Company's Basis)	$186,042,000	'	$180,512,000	($1,200,000)	'	'	'	'	'	'
Number of unconsolidated investments in Real Estate Ventures	17	17	'	'	'	'	'	'	'	'
Net rentable square feet	'	'	'	'	'	5,900,000	6,200,000	'	'	'
Number of Real Estate Properties	'	'	'	'	'	'	'	'	'	2
Net Rentable Space	'	'	'	'	'	'	'	'	'	192,396
Number of real estate ventures that owns buildings	11	'	'	'	'	'	'	'	'	'
Number of office buildings in Real Estate Ventures	56	'	'	'	'	'	'	'	'	'
Aggregate Approximate Area Of Office Buildings	5,900,000	'	'	'	'	'	'	'	'	'
Number of real estate ventures that owns undeveloped land	2	'	'	'	'	'	'	'	'	'
Area Owned By Real Estate Venture Of Undeveloped Parcels Of Land	3.8	'	'	'	'	'	'	'	'	'
Payments to Acquire Equity Method Investments	3,095,000	12,568,000	'	'	'	'	'	'	'	'
Number of real estate ventures that owns land under development	3	'	'	'	'	'	'	'	'	'
Area Owned By Real Estate Venture in Parcels Of Land Under Development	22.5	'	'	'	'	'	'	'	'	'
Number of real estate ventures developed hotel property	1	'	'	'	'	'	'	'	'	'
Number Of Rooms Contain In One Real Estate Venture Developed As Hotel Property	137	'	'	'	'	'	'	'	'	'
Minimum Percentage Of Unconsolidated Equity Method Investment Ownership	20.00%	'	'	'	'	'	'	'	'	'
Maximum Percentage Of Unconsolidated Equity Method Investment Ownership	65.00%	'	'	'	'	'	'	'	'	'
Guarantor Obligations, Current Carrying Value	'	'	'	'	$3,200,000	'	'	$24,700,000	$500,000	'

Investment_in_Unconsolidated_V3

Investment in Unconsolidated Ventures (Summary of Results of Operations of Unconsolidated Ventures) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Company's share of income (Company's basis)	($489)	$1,508	($247)	$3,043
Unconsolidated Real Estate Ventures [Member]	'	'	'	'
Schedule of Equity Method Investments [Line Items]	'	'	'	'
Revenue	35,074	36,927	69,459	77,816
Operating expenses	14,842	17,205	28,824	35,472
Interest expense, net	8,889	9,173	16,989	18,944
Depreciation and amortization	13,273	10,979	26,871	23,885
Net loss	-1,930	-430	-3,225	-485
Company's share of income (Company's basis)	($489)	$1,508	($247)	$3,043

Investment_in_Unconsolidated_V4

Investment in Unconsolidated Ventures (Financial Position of Unconsolidated Real Estate Ventures) (Details) (USD $)	Jun. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Equity Method Investments [Line Items]	'		'
Company's share of equity (Company's Basis)	$186,042		$180,512
Austin Joint Venture [Member]	'		'
Schedule of Equity Method Investments [Line Items]	'		'
Company's share of equity (Company's Basis)	-1,200		'
Unconsolidated Real Estate Ventures [Member]	'		'
Schedule of Equity Method Investments [Line Items]	'		'
Net property	1,081,064		965,475
Other assets	153,348		164,152
Other liabilities	68,031		49,442
Debt	792,919		699,860
Equity	373,462		380,325
Company's share of equity (Company's Basis)	$186,042	[1]	$180,512	[1]
[1]	(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.

Deferred_Costs_Details

Deferred Costs (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Components of Deferred Costs Net [Abstract]	'	'
Leasing Costs, Total Cost	$161,800	$155,885
Financing Costs, Total Cost	40,315	40,317
Total Cost	202,115	196,202
Leasing Costs, Accumulated Amortization	-61,694	-58,805
Financing Costs, Accumulated Amortization	-16,829	-14,443
Total, Accumulated Amortization	-78,523	-73,248
Leasing, Deferred Costs, Net	100,106	97,080
Financing Costs, Deferred Costs, Net	23,486	25,874
Deferred Costs, Net	$123,592	$122,954

Deferred_Costs_Details_Textual

Deferred Costs (Details Textuals) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Deferred Costs (Textuals) [Abstract]	'	'	'	'
Capitalized Internal Direct Leasing Costs	$2	$1.80	$4	$3.90

Intangible_Assets_Details

Intangible Assets (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Intangible Assets [Line Items]	'	'
Total Cost	$179,527	$196,147
Accumulated Amortization	-67,387	-63,818
Intangible Assets, net	112,140	132,329
In-place lease value	'	'
Intangible Assets [Line Items]	'	'
Total Cost	136,388	150,782
Accumulated Amortization	-38,767	-35,607
Intangible Assets, net	97,621	115,175
Tenant relationship value	'	'
Intangible Assets [Line Items]	'	'
Total Cost	37,019	38,692
Accumulated Amortization	-27,159	-26,868
Intangible Assets, net	9,860	11,824
Above market leases acquired	'	'
Intangible Assets [Line Items]	'	'
Total Cost	6,120	6,673
Accumulated Amortization	-1,461	-1,343
Intangible Assets, net	4,659	5,330
Below Market Leases Acquired [Member]	'	'
Intangible Assets [Line Items]	'	'
Total Cost	-64,679	-81,991
Accumulated Amortization	35,563	47,547
Intangible Assets, net	($29,116)	($34,444)

Intangible_Assets_Annual_Amort

Intangible Assets Annual Amortization of Intangible Assets (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Annual amortization of intangible assets and liabilities	'	'
Intangible Assets, net	($112,140)	($132,329)
Assets [Member]	'	'
Annual amortization of intangible assets and liabilities	'	'
2013	12,075	'
2014	21,581	'
2015	17,102	'
2016	15,279	'
2017	11,458	'
Thereafter	34,645	'
Intangible Assets, net	-112,140	'
Liabilities [Member]	'	'
Annual amortization of intangible assets and liabilities	'	'
2013	-3,093	'
2014	-5,223	'
2015	-3,254	'
2016	-2,664	'
2017	-2,241	'
Thereafter	-12,641	'
Intangible Assets, net	$29,116	'

Debt_Obligations_Consolidated_

Debt Obligations (Consolidated Debt Obligations Outstanding) (Details) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Debt Instrument [Line Items]	'		'
Net unamortized premiums/(discounts)	($4,409)		'
Total mortgage indebtedness	662,478		670,151
Total Debt Obligations	2,588,250		2,595,381
Secured Debt [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	662,956		669,762
Net unamortized premiums/(discounts)	-478		389
Total mortgage indebtedness	662,478		670,151
Unsecured Debt [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	1,929,703		1,929,703
Net unamortized premiums/(discounts)	-3,931		-4,473
Total unsecured indebtedness	1,925,772		1,925,230
Unsecured Debt [Member] | Three Year Term Loan [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	150,000		150,000
Debt Instrument, Interest Rate, Effective Percentage	2.60%		'
Debt Instrument, Maturity Date	1-Feb-15		'
Unsecured Debt [Member] | Four-Year Term Loan - Variable [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	100,000		100,000
Debt Instrument, Interest Rate Terms	'LIBOR + 1.75%	[1]	'
Debt Instrument, Maturity Date	1-Feb-16		'
Unsecured Debt [Member] | Seven Year Term Loan [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	200,000		200,000
Debt Instrument, Interest Rate, Effective Percentage	3.62%		'
Debt Instrument, Maturity Date	1-Feb-19		'
Unsecured Debt [Member] | 2014 5.400% Notes	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	218,549		218,549
Debt Instrument, Interest Rate, Effective Percentage	5.53%		'
Debt Instrument, Maturity Date	1-Nov-14		'
Unsecured Debt [Member] | $250.0M 7.500% Guaranteed Notes due 2015	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	157,625		157,625
Debt Instrument, Interest Rate, Effective Percentage	7.76%		'
Debt Instrument, Maturity Date	15-May-15		'
Unsecured Debt [Member] | $250.0M 6.000% Guranteed Notes due 2016 [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	149,919		149,919
Debt Instrument, Interest Rate, Effective Percentage	5.95%		'
Debt Instrument, Maturity Date	1-Apr-16		'
Unsecured Debt [Member] | $300.0M 5.700% Guaranteed Notes due 2017	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	300,000		300,000
Debt Instrument, Interest Rate, Effective Percentage	5.68%		'
Debt Instrument, Maturity Date	1-May-17		'
Unsecured Debt [Member] | $325.0M 4.950% Guaranteed Notes due 2018	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	325,000		325,000
Debt Instrument, Interest Rate, Effective Percentage	5.13%		'
Debt Instrument, Maturity Date	15-Apr-18		'
Unsecured Debt [Member] | $250.0M 3.950% Guaranteed Notes due 2023	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	250,000		250,000
Debt Instrument, Interest Rate, Effective Percentage	4.02%		'
Debt Instrument, Maturity Date	15-Feb-23		'
Unsecured Debt [Member] | Indenture IA (Preferred Trust I) [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	27,062		27,062
Debt Instrument, Interest Rate, Effective Percentage	2.75%		'
Debt Instrument, Maturity Date	30-Mar-35		'
Unsecured Debt [Member] | Indenture IB (Preferred Trust I) [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	25,774		25,774
Debt Instrument, Interest Rate, Effective Percentage	3.30%		'
Debt Instrument, Maturity Date	30-Apr-35		'
Unsecured Debt [Member] | Indenture II (Preferred Trust II) [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	25,774		25,774
Debt Instrument, Interest Rate, Effective Percentage	3.09%		'
Debt Instrument, Maturity Date	30-Jul-35		'
Tysons Corner [Member] | Secured Debt [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	90,460		91,395
Debt Instrument, Interest Rate, Effective Percentage	5.36%	[2]	'
Debt Instrument, Maturity Date	1-Aug-15		'
One Commerce Square [Member] | Secured Debt [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	124,151		125,089
Debt Instrument, Interest Rate, Effective Percentage	3.68%	[2]	'
Debt Instrument, Maturity Date	6-Jan-16		'
Two Logan Square [Member] | Secured Debt [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	88,174		88,583
Debt Instrument, Interest Rate, Effective Percentage	7.57%		'
Debt Instrument, Maturity Date	1-Apr-16		'
Fairview Eleven Tower [Member]	'		'
Debt Instrument [Line Items]	'		'
Equity Method Investment, Ownership Percentage	50.00%		'
Fairview Eleven Tower [Member] | Secured Debt [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	21,470		21,630
Debt Instrument, Interest Rate, Effective Percentage	4.25%	[3]	'
Debt Instrument, Maturity Date	1-Jan-17		'
Two Commerce Square [Member] | Secured Debt [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	112,000		112,000
Debt Instrument, Interest Rate, Effective Percentage	4.51%	[2]	'
Debt Instrument, Maturity Date	5-Apr-23		'
IRS Philadelphia Campus [Member] | Secured Debt [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	187,751		190,964
Debt Instrument, Interest Rate, Effective Percentage	7.00%		'
Debt Instrument, Maturity Date	10-Sep-30		'
Cira South Garage [Member] | Secured Debt [Member]	'		'
Debt Instrument [Line Items]	'		'
Long-term Debt, Gross	$38,950		$40,101
Debt Instrument, Interest Rate, Effective Percentage	7.12%		'
Debt Instrument, Maturity Date	10-Sep-30		'
[1]	London Interbank Offered Rate (“LIBOR”).
[2]	(a)These loans were assumed upon acquisition of the related properties. The interest rate reflects the market rate at the time of acquisition.
[3]	(b)Represents the full debt amount secured by a property owned by a consolidated real estate venture in which the Company holds a 50% interest.

Debt_Obligations_Aggregate_Sch

Debt Obligations (Aggregate Scheduled Principal Payments of Debt Obligation, Excluding Amortization of Discounts and Premiums) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Extinguishment of Debt [Line Items]	'	'
2013	$225,570	'
2014	409,655	'
2015	467,703	'
2016	330,323	'
2017	336,954	'
Thereafter	822,454	'
Total principal payments	2,592,659	'
Net unamortized premiums/(discounts)	-4,409	'
Total Debt Obligations	$2,588,250	$2,595,381

Debt_Obligations_Details_Textu

Debt Obligations (Details Textuals) (USD $)	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014
In Millions, unless otherwise specified	Secured Debt [Member]	Secured Debt [Member]	Unsecured Debt [Member]	Unsecured Debt [Member]	Unsecured Debt [Member]	Unsecured Debt [Member]	Unsecured Debt [Member]
			Three Year Term Loan [Member]	Letter of Credit [Member]	Line of Credit [Member]	Four Year Term Loan [Member]	Seven Year Term Loan [Member]
Debt Instrument [Line Items]	'	'	'	'	'	'	'
Long-term Debt, Weighted Average Interest Rate	5.73%	6.64%	'	'	'	'	'
Debt Instrument, Basis Spread on Variable Rate	'	'	'	1.50%	'	'	'
Letters of Credit Outstanding, Amount	'	'	'	$1.50	'	'	'
Line of Credit Facility, Remaining Borrowing Capacity	'	'	'	'	598.5	'	'
Debt Instrument, Face Amount	'	'	150	'	'	250	200
Line of Credit Facility, Option for Additional Borrowing Capacity subject to customary conditions and limitations	'	'	'	'	$200	'	'
Declining prepayment penalty after Three Years	'	'	'	'	'	'	1.00%
Derivative, Average Fixed Interest Rate	'	'	2.60%	'	'	'	3.62%

Debt_Obligations_Details_Textu1

Debt Obligations (Details Textuals 2) (Details) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014
Unsecured Debt [Member] | Four Year Term Loan [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Face Amount	$250
Debt Instrument, Interest Rate, Stated Percentage	5.40%
Unsecured Debt [Member] | $250.0M 7.500% Guaranteed Notes due 2015	'
Debt Instrument [Line Items]	'
Debt Instrument, Face Amount	250
Debt Instrument, Interest Rate, Stated Percentage	7.50%
Unsecured Debt [Member] | $250.0M 6.000% Guranteed Notes due 2016 [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Face Amount	250
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Unsecured Debt [Member] | $300.0M 5.700% Guaranteed Notes due 2017	'
Debt Instrument [Line Items]	'
Debt Instrument, Face Amount	300
Debt Instrument, Interest Rate, Stated Percentage	5.70%
Unsecured Debt [Member] | $325.0M 4.950% Guaranteed Notes due 2018	'
Debt Instrument [Line Items]	'
Debt Instrument, Face Amount	325
Debt Instrument, Interest Rate, Stated Percentage	4.95%
Unsecured Debt [Member] | $250.0M 3.950% Guaranteed Notes due 2023	'
Debt Instrument [Line Items]	'
Debt Instrument, Face Amount	250
Debt Instrument, Interest Rate, Stated Percentage	3.95%
Unsecured Debt [Member] | Three Year Term Loan [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Face Amount	150
Debt Instrument Term	'3 years
Option to Extend Term Loan	'1 year
Unsecured Debt [Member] | Four-Year Term Loan - Variable [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Face Amount	100
Debt Instrument Term	'4 years
Option to Extend Term Loan	'1 year
Debt Instrument, Basis Spread on Variable Rate	1.75%
Unsecured Debt [Member] | Letter of Credit [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Basis Spread on Variable Rate	1.50%
Unsecured Debt [Member] | Three and Four Year Term Loan [Member]	'
Debt Instrument [Line Items]	'
Derivative, Lower Remaining Maturity Range	'3 years
Derivative, Higher Remaining Maturity Range	'4 years
Unsecured Debt [Member] | Seven Year Term Loan [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Face Amount	$200
Debt Instrument Term	'7 years
Senior notes 5.400 Percent due 2014 [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Interest Rate, Stated Percentage	5.40%
Senior Notes Due2015 [Member]	'
Debt Instrument [Line Items]	'
Debt Instrument, Interest Rate, Stated Percentage	7.50%

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Company's estimates of fair value differ from the carrying amounts	'	'
Mortgage notes payable	$662,478	$670,151
Mortgage notes payable, Fair Value	697,731	715,244
Unsecured Notes Payable, Carrying Amount	1,397,162	1,396,620
Unsecured Notes Payable, Fair Value	1,478,767	1,471,041
Variable Rate Debt, Carrying Amount	528,610	528,610
Variable Rate Debt, Fair Value	504,044	526,693
Notes Receivable, Carrying Amount	4,226	7,026
Notes Receivable, Fair Value	$5,088	$7,759

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments (Details Textuals) (Details)	6 Months Ended
	Jun. 30, 2014
Notes Receivable [Member]	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'
Fair Value Inputs, Discount Rate	14.82%
Variable rate and mortgage debt [Member]	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'
Fair Value Inputs, Discount Rate	3.47%

Risk_Management_and_Use_of_Fin2

Risk Management and Use of Financial Instruments (Fair Values of Derivative Financial Instruments) (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Other Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative, Notional Amount	$428,610	$428,610
Derivative, Fair Value, Net	-4,685	-1,421
3.300% Interest Rate Swap Maturing January 30, 2021 [Member] | Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Other Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative, Notional Amount	25,774	25,774
Derivative, Fixed Interest Rate	3.30%	'
Derivative, Fair Value, Net	-128	549
3.090% Interest Rate Swap Maturing October 30, 2019 [Member] | Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Other Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative, Notional Amount	25,774	25,774
Derivative, Fixed Interest Rate	3.09%	'
Derivative, Fair Value, Net	-214	218
3.623% Interest Rate Swap Maturing February 1, 2019 [Member] | Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Other Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative, Notional Amount	200,000	200,000
Derivative, Fixed Interest Rate	3.62%	'
Derivative, Fair Value, Net	-2,843	-545
2.703% Interest Rate Swap Maturing February 1, 2016 [Member] | Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Other Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative, Notional Amount	77,000	77,000
Derivative, Fixed Interest Rate	2.70%	'
Derivative, Fair Value, Net	-799	-887
2.470% Interest Rate Swap Maturing February 1, 2015 [Member] | Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Other Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative, Notional Amount	50,000	50,000
Derivative, Fixed Interest Rate	2.47%	'
Derivative, Fair Value, Net	-191	-283
2.513% Interest Rate Swap Maturing May 1, 2015 [Member] | Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Other Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative, Notional Amount	23,000	23,000
Derivative, Fixed Interest Rate	2.51%	'
Derivative, Fair Value, Net	-125	-162
2.750% Interest Rate Swap Maturing September 30, 2017 [Member] | Cash Flow Hedging [Member] | Interest Rate Swap [Member] | Other Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative, Notional Amount	27,062	27,062
Derivative, Fixed Interest Rate	2.75%	'
Derivative, Fair Value, Net	($385)	($311)

Discontinued_Operations_Detail

Discontinued Operations (Details) (USD $)	3 Months Ended		6 Months Ended		0 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Apr. 07, 2014	Feb. 25, 2014	Jun. 30, 2013	Jun. 30, 2013
					Princeton Pike Corporate Center [Member]	Princeton Pike Corporate Center [Member]	Discontinued Operations [Member]	Discontinued Operations [Member]
Revenue:	'	'	'	'	'	'	'	'
Rents	$121,622	$116,064	$243,293	$230,672	'	'	$895	$4,658
Termination fees	3,349	410	5,552	906	'	'	0	0
Other Real Estate Revenue	840	1,457	1,470	2,330	'	'	9	123
Tenant reimbursements	20,502	19,560	43,962	39,901	'	'	7	345
Total revenue	150,500	140,644	302,614	280,198	'	'	911	5,126
Expenses:	'	'	'	'	'	'	'	'
Property operating expenses	43,136	39,433	89,937	78,782	'	'	330	1,711
Real estate taxes	12,841	14,177	26,298	28,472	'	'	118	584
Depreciation and amortization	52,587	49,241	105,157	98,717	'	'	337	1,845
Total operating expenses	116,299	111,550	239,024	222,646	'	'	785	4,140
Interest income	385	122	770	180	'	'	3	3
Income from discontinued operations before gain on sale of interests in real estate	26	129	18	989	'	'	129	989
Net gain on disposition of discontinued operations	903	-2,259	903	3,045	900	5,300	-2,259	3,045
Income (Loss) from discontinued operations	$929	($2,130)	$921	$4,034	'	'	($2,130)	$4,034

Discontinued_Operations_Detail1

Discontinued Operations (Details Textuals) (Details) (USD $)	3 Months Ended		6 Months Ended		0 Months Ended	12 Months Ended		3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Apr. 07, 2014	Feb. 25, 2014	Feb. 25, 2013	Jun. 30, 2013	Jun. 30, 2013	Dec. 31, 2013
					Princeton Pike Corporate Center [Member]	Princeton Pike Corporate Center [Member]	Princeton Pike Corporate Center [Member]	Discontinued Operations [Member]	Discontinued Operations [Member]	Discontinued Operations [Member]
										Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'	'	'	'	'	'
Business Acquisition, Transaction Costs	'	'	'	'	'	'	$2,000,000	'	'	'
Net gain on disposition of discontinued operations	$903,000	($2,259,000)	$903,000	$3,045,000	$900,000	$5,300,000	'	($2,259,000)	$3,045,000	'
Number of properties sold	'	'	'	'	'	'	'	'	'	14

Non_Controlling_Interests_In_t1

Non Controlling Interests In the Parent Company (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Noncontrolling Interest [Abstract]	'	'
Aggregate amount related to non-controlling interests classified within equity	$19.70	$20.30
Settlement Value Of Non Controlling Interest In Operating Partnership	$27.50	$24.80

Beneficiaries_Equity_of_the_Pa2

Beneficiaries Equity of the Parent Company (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator	'	'	'	'
Income (Loss) from Continuing Operations, Basic	$1,245	$9,310	($992)	$7,065
Income (Loss) From Continuing Operations, Diluted	1,245	9,310	-992	7,065
Net Income (Loss) From Continuing Operations Attributable to Non controlling interests, Basic	5	-87	49	-37
Net Income (Loss) From Continuing Operations Attributable To Non Controlling Interests, Diluted	5	-87	49	-37
Net income attributable to non-controlling interest — partners' share of consolidated real estate ventures	24	0	12	0
Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Redeemable, Diluted	24	0	12	0
Amount allocated to unvested restricted shareholders/unitholders, Basic	-83	-85	-186	-193
Amount allocated to unvested restricted shareholders/unitholders, Diluted	-83	-85	-186	-193
Preferred share/unit dividends, Basic	-1,725	-1,725	-3,450	-3,450
Preferred share/unit dividends, Diluted	-1,725	-1,725	-3,450	-3,450
Income (Loss) from continuing operations available to common unitholders, Basic	-534	7,413	-4,567	3,385
Income (Loss) from continuing operations available to common unitholders, Diluted	-534	7,413	-4,567	3,385
Income (Loss) from Discontinued Operations	929	-2,130	921	4,034
Income (Loss) From Discontinued Operations, Diluted	929	-2,130	921	4,034
Discontinued operations attributable to non-controlling interests, Basic	-10	25	-10	-53
Discontinued Operations Attributable to Noncontrolling Interests- Diluted	-10	25	-10	-53
Discontinued operations attributable to common shareholders, Basic	919	-2,105	911	3,981
Discontinued operations attributable to common shareholders, Diluted	919	-2,105	911	3,981
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	385	5,308	-3,656	7,366
Net Income (Loss) Available to Common Shareholders/unitholders, Diluted	$385	$5,308	($3,656)	$7,366
Denominator	'	'	'	'
Weighted Average Number of Shares Outstanding, Basic	157,037,348	155,347,384	156,916,356	149,508,957
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	0	1,343,817	0	1,157,288
Weighted Average Number of Shares Outstanding, Diluted	157,037,348	156,691,201	156,916,356	150,666,245
Earnings per common share from continuing operations Abstract	'	'	'	'
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Basic Share	$0	$0.05	($0.03)	$0.02
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Diluted Share	$0	$0.05	($0.03)	$0.02
Discontinued Operations attributable to common shareholders/unitholders, Basic	$0	($0.02)	$0.01	$0.03
Discontinued Operations attributable to common shareholders/unitholders, Diluted	$0	($0.02)	$0.01	$0.03
Net income (loss) attributable to common shareholders/unitholders, Basic	$0	$0.03	($0.02)	$0.05
Net income attributable to common shareholders/unitholders, Diluted	$0	$0.03	($0.02)	$0.05

Beneficiaries_Equity_of_the_Pa3

Beneficiaries Equity of the Parent Company (Details Textuals) (Details) (USD $)

6 Months Ended

12 Months Ended

6 Months Ended

0 Months Ended

6 Months Ended

12 Months Ended

In Thousands, except Share data, unless otherwise specified

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

15-May-14

14-May-14

Feb. 07, 2014

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Nov. 05, 2013

Jul. 07, 2014

Jul. 15, 2014

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

Jul. 07, 2014

Class A Units [Member]

Class A Units [Member]

Series E Preferred Stock [Member]

Offering Program [Member]

Dividend Paid [Member]

Dividend Paid [Member]

BRANDYWINE OPERATING PARTNERSHIP, L.P.

BRANDYWINE OPERATING PARTNERSHIP, L.P.

BRANDYWINE OPERATING PARTNERSHIP, L.P.

BRANDYWINE OPERATING PARTNERSHIP, L.P.

Series E Preferred Stock [Member]

Dividend Paid [Member]

Class of Stock [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount

'

'

'

'

'

'

1,763,739

1,763,739

'

'

'

'

'

'

'

'

Proceeds from Issuance of Common Stock

$0

$181,527

'

'

'

'

'

'

'

'

'

'

$0

$181,527

'

'

Dividends Payable, Amount Per Share

'

'

'

'

'

$0.15

'

'

'

'

'

'

'

'

'

'

Distributions payable

25,588

'

25,584

'

'

'

'

'

'

'

23,600

'

25,588

'

25,584

23,900

Preferred Stock, Shares Issued

4,000,000

'

4,000,000

'

'

'

'

'

'

'

'

'

4,000,000

'

4,000,000

'

Preferred Stock, Dividend Rate, Percentage

6.90%

'

6.90%

'

'

'

'

'

6.90%

'

'

'

6.90%

'

6.90%

'

Preferred Stock, Liquidation Preference Per Share

'

'

'

'

'

'

'

'

$25

'

'

'

'

'

'

'

Dividends, Preferred Stock, Cash

$3,450

$3,450

'

'

'

'

'

'

'

'

'

$1,700

'

'

'

'

Shares of Beneficial Interest, Shares Authorized

'

'

'

420,000,000

220,000,000

'

'

'

'

'

'

'

'

'

'

'

Shares Authorized For Equity Offering Program

'

'

'

'

'

'

'

'

'

16,000,000

'

'

'

'

'

'

Remaining Shares Available For Sales

'

'

'

'

'

'

'

'

'

16,000,000

'

'

'

'

'

'

Common Stock, Shares Authorized

400,000,000

'

200,000,000

400,000,000

200,000,000

'

'

'

'

'

'

'

'

'

'

'

Preferred Stock, Shares Authorized

20,000,000

'

20,000,000

20,000,000

'

'

'

'

'

'

'

'

'

'

'

'

Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased

539,200

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Partners_Equity_of_the_Operati2

Partners Equity of the Operating Partnership (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Numerator	'	'	'	'
Income (Loss) from Continuing Operations, Basic	$1,245	$9,310	($992)	$7,065
Income (Loss) From Continuing Operations, Diluted	1,245	9,310	-992	7,065
Amount allocated to unvested restricted shareholders/unitholders, Basic	-83	-85	-186	-193
Amount allocated to unvested restricted shareholders/unitholders, Diluted	-83	-85	-186	-193
Preferred share/unit dividends, Basic	-1,725	-1,725	-3,450	-3,450
Preferred share/unit dividends, Diluted	-1,725	-1,725	-3,450	-3,450
Net income attributable to non-controlling interest — partners' share of consolidated real estate ventures	24	0	12	0
Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Redeemable, Diluted	-24	0	-12	0
Income (Loss) from continuing operations available to common unitholders, Basic	-534	7,413	-4,567	3,385
Income (Loss) from continuing operations available to common unitholders, Diluted	-534	7,413	-4,567	3,385
Income (Loss) from Discontinued Operations	929	-2,130	921	4,034
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	385	5,308	-3,656	7,366
Net Income (Loss) Available to Common Shareholders/unitholders, Diluted	385	5,308	-3,656	7,366
Denominator	'	'	'	'
Weighted-average units outstanding, Basic	157,037,348	155,347,384	156,916,356	149,508,957
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	0	1,343,817	0	1,157,288
Weighted Average Number of Shares Outstanding, Diluted	157,037,348	156,691,201	156,916,356	150,666,245
Earnings per Common Partnership Unit [Abstract]	'	'	'	'
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Basic Share	$0	$0.05	($0.03)	$0.02
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Diluted Share	$0	$0.05	($0.03)	$0.02
Discontinued Operations attributable to common shareholders/unitholders, Basic	$0	($0.02)	$0.01	$0.03
Discontinued Operations attributable to common shareholders/unitholders, Diluted	$0	($0.02)	$0.01	$0.03
Net income (loss) attributable to common shareholders/unitholders, Basic	$0	$0.03	($0.02)	$0.05
Net income attributable to common shareholders/unitholders, Diluted	$0	$0.03	($0.02)	$0.05
BRANDYWINE OPERATING PARTNERSHIP, L.P.	'	'	'	'
Numerator	'	'	'	'
Income (Loss) from Continuing Operations, Basic	1,245	9,310	-992	7,065
Income (Loss) From Continuing Operations, Diluted	1,245	9,310	-992	7,065
Amount allocated to unvested restricted shareholders/unitholders, Basic	-83	-85	-186	-193
Amount allocated to unvested restricted shareholders/unitholders, Diluted	-83	-85	-186	-193
Preferred share/unit dividends, Basic	-1,725	-1,725	-3,450	-3,450
Preferred share/unit dividends, Diluted	-1,725	-1,725	-3,450	-3,450
Net income attributable to non-controlling interest — partners' share of consolidated real estate ventures	24	0	12	0
Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Redeemable, Diluted	-24	0	-12	0
Income (Loss) from continuing operations available to common unitholders, Basic	-539	7,500	-4,616	3,422
Income (Loss) from continuing operations available to common unitholders, Diluted	-539	7,500	-4,616	3,422
Income (Loss) from Discontinued Operations	929	-2,130	921	4,034
Income (Loss) From Discontinued Operations, Diluted	929	-2,130	921	4,034
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	390	5,370	-3,695	7,456
Net Income (Loss) Available to Common Shareholders/unitholders, Diluted	$390	$5,370	($3,695)	$7,456
Denominator	'	'	'	'
Weighted-average units outstanding, Basic	158,801,087	157,131,697	158,680,095	151,323,813
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	0	1,343,817	0	1,157,288
Weighted Average Number of Shares Outstanding, Diluted	158,801,087	158,475,514	158,680,095	152,481,101
Earnings per Common Partnership Unit [Abstract]	'	'	'	'
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Basic Share	$0	$0.05	($0.03)	$0.02
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Diluted Share	$0	$0.05	($0.03)	$0.02
Discontinued Operations attributable to common shareholders/unitholders, Basic	$0	($0.02)	$0.01	$0.03
Discontinued Operations attributable to common shareholders/unitholders, Diluted	$0	($0.02)	$0.01	$0.03
Net income (loss) attributable to common shareholders/unitholders, Basic	$0	$0.03	($0.02)	$0.05
Net income attributable to common shareholders/unitholders, Diluted	$0	$0.03	($0.02)	$0.05

Partners_Equity_of_the_Operati3

Partners Equity of the Operating Partnership (Details Textuals) (Details) (USD $)

6 Months Ended

12 Months Ended

6 Months Ended

12 Months Ended

6 Months Ended

0 Months Ended

In Thousands, except Per Share data, unless otherwise specified

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

Feb. 07, 2014

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

Jun. 30, 2014

Jul. 07, 2014

Jul. 07, 2014

Jul. 15, 2014

29-May-14

29-May-14

BRANDYWINE OPERATING PARTNERSHIP, L.P.

BRANDYWINE OPERATING PARTNERSHIP, L.P.

BRANDYWINE OPERATING PARTNERSHIP, L.P.

6.90% Series E-linked Preferred Units [Member]

Dividend Paid [Member]

Dividend Paid [Member]

Dividend Paid [Member]

Dividend Declared [Member]

Dividend Declared [Member]

BRANDYWINE OPERATING PARTNERSHIP, L.P.

BRANDYWINE OPERATING PARTNERSHIP, L.P.

6.90% Series E-linked Preferred Units [Member]

BRANDYWINE OPERATING PARTNERSHIP, L.P.

BRANDYWINE OPERATING PARTNERSHIP, L.P.

Earnings per Common Partnership Unit [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Dividends Payable, Amount Per Share

'

'

'

$0.15

'

'

'

'

'

'

'

$0.15

$0.15

Proceeds from Issuance of Common Stock

$0

$181,527

'

'

$0

$181,527

'

'

'

'

'

'

'

Distributions payable

25,588

'

25,584

'

25,588

'

25,584

'

23,600

23,900

'

'

'

Preferred Stock, Dividend Rate, Percentage

6.90%

'

6.90%

'

6.90%

'

6.90%

6.90%

'

'

'

'

'

Preferred Stock, Liquidation Preference Per Share

'

'

'

'

'

'

'

$25

'

'

'

'

'

Dividends, Preferred Stock, Cash

$3,450

$3,450

'

'

'

'

'

'

'

'

$1,700

'

'

Share_Based_and_Deferred_Compe2

Share Based and Deferred Compensation (Option Activity) (Details) (USD $)	6 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Jun. 30, 2013	Mar. 31, 2014
			Stock Option [Member]	Stock Option [Member]	Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'
Allocated Share-based Compensation Expense	'	'	$200,000	$400,000	'
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	'4 years 8 months 0 days	'5 years 1 month 25 days	'	'	'
Share Based Compensation Arrangement By Share Based Payment Award Option Activity [Abstract]	'	'	'	'	'
Outstanding at the beginning of year, shares	2,983,569	'	'	'	2,808,784
Outstanding at beginning of year, Weighted Average Exercise Price	$15.50	'	'	'	'
Outstanding at beginning of year, Aggregate Intrinsic Value	0	'	'	'	'
Granted, shares	0	'	'	'	'
Granted, Weighted Average Grant Date Fair Value	$0	'	'	'	'
Exercised in Period, Shares	-60,127	'	'	'	'
Exercises in Period, Weighted Average Grant Date Fair Value	$11.80	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	182,101	'	'	'	'
Forfeited, shares	-114,658	'	'	'	'
Forfeited, Weighted Average Grant Date Fair Value	$20.61	'	'	'	'
Outstanding at the end of year, shares	2,808,784	2,983,569	'	'	2,808,784
Outstanding at end of year, Weighted Average Exercise Price	$15.37	$15.50	'	'	'
Outstanding at end of year, Aggregate Intrinsic Value	632,239	0	'	'	'
Vested/Exerciseable, shares	2,808,784	'	'	'	'
Vested/Exerciseable at end of period, Weigted Average Exercise Price	$15.37	'	'	'	'
Vested/Exerciseable at end of period, Weighted Average Remaining Contractual Term (in years)	'4 years 8 months 0 days	'	'	'	'
Vested/Exercisable at end of year, Aggregate Intrinsic Value	632,239	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	'	'	'	$100,000	'

Share_Based_and_Deferred_Compe3

Share Based and Deferred Compensation (Restricted Share Activity) (Details) (Restricted Stock [Member], USD $)	3 Months Ended		6 Months Ended
In Millions, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Mar. 12, 2014	Mar. 11, 2014
					Executive Officer [Member]	Executive Officer [Member]	Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares	'	'	'	'	68,049	'	'
Allocated Share-based Compensation Expense	$0.50	$0.90	$1.90	$1.80	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	'	'	'	'	'	69,794	131,641
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	'	'	'	'	'15 years	'	'
Non-vested at January 1, 2013, shares	550,222	'	563,713	'	'	'	'
Non-vested at January 1, 2013, Weighted Average Grant Date Fair Value	$12.22	'	$12.56	'	'	'	'
Granted, Equity Instruments Other than Options, Grants in Period	'	'	229,119	'	'	'	'
Granted, Weighted Average Grant Date Fair Value	'	'	$14.47	'	'	'	'
Vested, shares	'	'	-234,169	'	'	'	'
Vested, Weighted Average Grant Date Fair Value	'	'	$13.44	'	'	'	'
Forfeited, shares	'	'	-8,441	'	'	'	'
Forfeited, Weighted Average Grant Date Fair Value	'	'	$12.36	'	'	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	$0.10	$0.10	$0.40	$0.30	'	'	'

Share_Based_and_Deferred_Compe4

Share Based and Deferred Compensation (Details Textuals) (Details) (USD $)

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

6 Months Ended

0 Months Ended

3 Months Ended

6 Months Ended

0 Months Ended

12 Months Ended

Jun. 30, 2014

Feb. 07, 2014

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Mar. 31, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Mar. 01, 2014

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Mar. 12, 2014

Mar. 11, 2014

Mar. 11, 2014

Mar. 12, 2014

Mar. 01, 2012

Feb. 25, 2014

Feb. 25, 2013

Stock Option [Member]

Stock Option [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Performance Share Units Plan [Member]

Restricted Performance Share Units Plan [Member]

Restricted Performance Share Units Plan [Member]

Restricted Performance Share Units Plan [Member]

Restricted Performance Share Units Plan [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Minimum [Member]

Maximum [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Stock [Member]

Restricted Performance Share Units Plan [Member]

Restricted Performance Share Units Plan [Member]

Restricted Performance Share Units Plan [Member]

Restricted Performance Share Units Plan [Member]

Restricted Performance Share Units Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

69,794

131,641

134,284

61,720

265,222

'

231,093

Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,745

'

'

'

'

'

'

'

Voluntary Termination Of Employment Terms

'

'

'

'

'

'

'after reaching age 57 and accumulating at least 15 years of service with the Company

'

'

'

'

'

'

'

'

'after reaching age 57 and accumulating at least 15 years of service with the Company

'

'

'

'

'

'

'

'

'

Accumulated Service Period For Voluntary Termination

'

'

'

'

'

'

'15 years

'

'

'

'

'

'

'

'

'15 years

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Term, Minimum

'3 years

'

'

'

'

'

'3 years

'

'

'

'3 years

'7 years

'

'

'

'3 years

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period

'

'

'

'

'

'

'three years from the initial grant dates

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum Percentage Of Participants Base Units

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

200.00%

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2,624,000

$1,225,000

$4,273,000

$4,137,000

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

'

'

'

'

'

'

'

'

550,222

563,713

'

'

'

'

'

'

'

'

'

'

134,284

61,720

211,521

'

203,395

Vested/Exerciseable, shares

2,808,784

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition

'

'

'

'

'

'

'1 year 10 months 25 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized

'

'

'

'

'

'

'

'

2,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Allocated Share-based Compensation Expense

'

'

200,000

400,000

500,000

900,000

1,900,000

1,800,000

'

'

'

'

'

500,000

1,300,000

2,300,000

2,500,000

'

'

'

'

'

'

'

'

Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount

'

'

'

$100,000

$100,000

$100,000

$400,000

$300,000

'

'

'

'

'

$200,000

$200,000

$700,000

$400,000

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period

'

'

'

'

'

'

234,169

'

'

'

'

'

150,829

'

'

'

'

'

'

'

'

'

'

'

'

Age Limit Of Voluntary Termination Of Employment

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

57

'

'

'

'

'

'

'

Dividends Payable, Amount Per Share

'

$0.15

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share_Based_and_Deferred_Compe5

Share Based and Deferred Compensation Restricted Performance Share Units (Details) (Restricted Performance Share Units Plan [Member], USD $)

0 Months Ended

3 Months Ended

6 Months Ended

0 Months Ended

12 Months Ended

6 Months Ended

0 Months Ended

Mar. 01, 2014

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Mar. 11, 2014

Mar. 12, 2014

Oct. 31, 2012

Mar. 01, 2012

Feb. 25, 2014

Feb. 25, 2013

Jun. 30, 2014

Oct. 31, 2012

Oct. 31, 2012

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Executive Officer [Member]

Rate

Original Grant [Member]

Dividend equivalent shares vested [Member]

Total vested [Member]

Rate

Rate

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Age Limit Of Voluntary Termination Of Employment

'

'

'

'

'

'

'

'

'

'

'

57

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period

'

'

'

'

'

'

'

'

'

'

'

'15 years

'

'

Allocated Share-based Compensation Expense

'

$500,000

$1,300,000

$2,300,000

$2,500,000

'

'

'

'

'

'

'

'

'

Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount

'

200,000

200,000

700,000

400,000

'

'

'

'

'

'

'

'

'

Fair Value of Units on Grant Date

'

'

'

'

'

$2,624,000

$1,225,000

'

$4,273,000

$4,137,000

'

'

'

'

Units Granted

'

'

'

'

'

134,284

61,720

'

265,222

'

231,093

'

'

'

Units Canceled

'

'

'

'

'

'

'

'

38,959

27,698

'

'

'

'

Units Vested

-150,829

'

'

'

'

'

'

'

'

'

'

-14,742

[1]

'

'

Unvested Balance

'

'

'

'

'

134,284

61,720

'

211,521

'

203,395

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate

'

'

'

'

'

'

'

200.00%

'

'

'

'

56300.00%

3061000.00%

[1]

(a) These RPSUs were settled upon the holder’s qualifying retirement in October 2012 after reaching age 57 and accumulating at least 15 years of service with the Company. Of the 14,742 RPSU's originally granted, 563 dividend equivalent rights were accrued at the time of qualifying retirement and the Company issued 30,610 shares in settlement of the RPSU's based on the Company’s total shareholder return-based performance achievement, as computed under the award agreement, on October 31, 2012 of 200%.

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended			6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014		Jun. 30, 2013	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Net gain on sale of interests in real estate	'		'	($2,087)		($3,044)	'
Operating properties	4,689,892		'	4,689,892		'	4,669,289
Construction-in-progress	92,713		'	92,713		'	74,174
Land inventory	90,266		'	90,266		'	93,351
Investment in real estate ventures, at equity	186,042		'	186,042		'	180,512
Total revenue	150,500		140,644	302,614		280,198	'
Property operating expenses	-57,707		-54,973	-119,681		-110,042	'
Gross Profit	92,793		85,671	182,933		170,156	'
Equity in income (loss) of real estate ventures	-489		1,508	-247		3,043	'
Depreciation and amortization	52,587		49,241	105,157		98,717	'
General and administrative expenses	6,005		7,336	14,186		13,887	'
Interest Expense, Debt	31,512		30,437	63,356		61,351	'
Amortization of deferred financing costs	1,197		1,183	2,386		2,344	'
Interest Expense, Other	316		211	588		429	'
Loss on early extinguishment of debt	0		-1,113	0		-1,116	'
Gain (Loss) on sale of undepreciated real estate	-3		0	1,184		0	'
Income (Loss) from Continuing Operations, Basic	1,245		9,310	-992		7,065	'
Income (Loss) from Discontinued Operations	929		-2,130	921		4,034	'
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	2,174		7,180	-71		11,099	'
Philadelphia CBD [Member]	'		'	'		'	'
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Operating properties	1,321,740		'	1,321,740		'	1,300,666
Investment in real estate ventures, at equity	20,689		'	20,689		'	19,975
Total revenue	51,420		36,142	100,834		72,067	'
Property operating expenses	-18,789		-13,587	-37,231		-27,121	'
Gross Profit	32,631		22,555	63,603		44,946	'
Equity in income (loss) of real estate ventures	0		577	-21		1,143	'
Pennsylvania [Member]	'		'	'		'	'
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Operating properties	1,228,752		'	1,228,752		'	1,199,105
Investment in real estate ventures, at equity	17,544		'	17,544		'	17,272
Total revenue	40,743		37,002	81,317		74,918	'
Property operating expenses	-13,742		-13,704	-28,431		-28,310	'
Gross Profit	27,001		23,298	52,886		46,608	'
Equity in income (loss) of real estate ventures	-391		558	-359		588	'
Metropolitan Dc [Member]	'		'	'		'	'
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Operating properties	1,221,305		'	1,221,305		'	1,214,965
Investment in real estate ventures, at equity	61,604		'	61,604		'	59,905
Total revenue	28,949		28,783	59,639		56,568	'
Property operating expenses	-10,505		-10,773	-22,462		-21,536	'
Gross Profit	18,444		18,010	37,177		35,032	'
Equity in income (loss) of real estate ventures	-42		-35	25		-19	'
New Jersey/ Delaware [Member]	'		'	'		'	'
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Operating properties	414,754		'	414,754		'	414,716
Investment in real estate ventures, at equity	0		'	0		'	0
Total revenue	14,841		15,024	30,466		29,944	'
Property operating expenses	-7,531		-6,871	-16,223		-13,902	'
Gross Profit	7,310		8,153	14,243		16,042	'
Equity in income (loss) of real estate ventures	103		167	122		1,075	'
Richmond, Virginia [Member]	'		'	'		'	'
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Operating properties	310,751		'	310,751		'	310,397
Investment in real estate ventures, at equity	1,295		'	1,295		'	1,400
Total revenue	8,322		8,954	17,189		17,719	'
Property operating expenses	-3,566		-3,599	-7,906		-7,282	'
Gross Profit	4,756		5,355	9,283		10,437	'
Equity in income (loss) of real estate ventures	115		243	69		236	'
Austin, Texas [Member]	'		'	'		'	'
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Operating properties	0	[1]	'	0	[1]	'	36,856
Investment in real estate ventures, at equity	84,910		'	84,910		'	81,960
Total revenue	976		9,872	3,057		19,129	'
Property operating expenses	-617		-4,207	-1,793		-8,165	'
Gross Profit	359		5,665	1,264		10,964	'
Equity in income (loss) of real estate ventures	-274		-2	-83		20	'
California	'		'	'		'	'
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Operating properties	192,590		'	192,590		'	192,584
Total revenue	4,895		4,536	9,497		9,141	'
Property operating expenses	-2,515		-2,338	-4,923		-4,498	'
Gross Profit	2,380		2,198	4,574		4,643	'
Corporate [Member]	'		'	'		'	'
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Construction-in-progress	92,713		'	92,713		'	74,174
Land inventory	90,266		'	90,266		'	93,351
Total revenue	354		331	615		712	'
Property operating expenses	-442		106	-712		772	'
Gross Profit	-88		437	-97		1,484	'
Austin Joint Venture [Member]	'		'	'		'	'
Real Estate Investments At Cost [Abstract]	'		'	'		'	'
Investment in real estate ventures, at equity	($1,200)		'	($1,200)		'	'
[1]	(a)On April 3, 2014, the Company contributed Four Points Centre to an unconsolidated joint venture. See Note 3 for further information on the contribution. Following the contribution, there are no wholly owned properties in the Austin, Texas segment.

Segment_Information_Reconcilia

Segment Information (Reconciliation of Consolidated Net Operating Income) (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
			Reportable_Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]	'	'	'	'
Consolidated net operating income	$92,793	$85,671	$182,933	$170,156
Other income (expense):	'	'	'	'
Depreciation and amortization	-52,587	-49,241	-105,157	-98,717
General and administrative expenses	-6,005	-7,336	-14,186	-13,887
Interest income	385	122	770	180
Interest expense	-31,512	-30,437	-63,356	-61,351
Amortization of deferred financing costs	-1,197	-1,183	-2,386	-2,344
Interest expense — financing obligation	-316	-211	-588	-429
Equity in income (loss) of real estate ventures	-489	1,508	-247	3,043
Gain (Loss) on sale of undepreciated real estate	-3	0	1,184	0
Gain from remeasurement of investment in real estate ventures	458	7,847	458	7,847
Gain (loss) on real estate venture transactions	-282	3,683	-417	3,683
Loss on early extinguishment of debt	0	-1,113	0	-1,116
Income (loss) from continuing operations	1,245	9,310	-992	7,065
Income (Loss) from Discontinued Operations	929	-2,130	921	4,034
Net income	$2,174	$7,180	($71)	$11,099
Number of Reportable Segments	'	'	7	'

Commitments_and_Contingencies_1

Commitments and Contingencies (Details)	Jun. 30, 2014
	Y
Long-term Purchase Commitment [Line Items]	'
Minimum remaining lease period	7
Maximum remaining lease period	75

Commitments_and_Contingencies_2

Commitments and Contingencies (Ground Rent) (Details) (Ground Rent [Member], USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
Ground Rent [Member]	'
Long-term Purchase Commitment [Line Items]	'
2014 (six months remaining)	$690
2014	1,380
2015	1,380
2016	1,380
2017	1,380
Thereafter	58,516
Operating Leases, Future Minimum Payments Due	$64,726