Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Real estate investments:
Rental properties	$ 4,639,047	$ 4,793,080
Accumulated depreciation	(897,367)	(865,710)
Operating real estate investments, net	3,741,680	3,927,370
Construction-in-progress	57,420	25,083
Land inventory	109,564	109,008
Total real estate investments, net	3,908,664	4,061,461
Cash and cash equivalents	190,055	410
Accounts receivable, net	11,445	14,718
Accrued rent receivable, net	113,380	108,101
Assets Held-for-sale, at Carrying Value	41,450	0
Investment in real estate ventures, at equity	133,292	115,807
Deferred costs, net	114,920	115,362
Intangible assets, net	57,927	70,515
Notes receivable	7,226	18,186
Other assets	48,739	53,158
Total assets	4,669,170	4,557,718
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	505,214	511,061
Unsecured credit facility	0	275,500
Unsecured term loans	600,000	37,500
Unsecured senior notes, net of discounts	1,404,627	1,569,934
Accounts payable and accrued expenses	57,653	69,929
Distributions payable	24,889	23,895
Deferred income, gains and rent	95,390	99,569
Acquired lease intangibles, net	31,526	35,106
Other liabilities	55,264	45,528
Liabilities of Assets Held-for-sale	878	0
Total liabilities	2,775,441	2,668,022
Commitments and contingencies (Note 17)
Brandywine Realty Trust's equity:
Preferred Shares	96,850
Common Shares of Brandywine Realty Trust’s beneficial interest, $0.01 par value; shares authorized 200,000,000; 143,367,946 and 142,690,755 issued in 2012 and 2011, respectively and 143,367,946 and 142,690,755 outstanding in 2012 and 2011, respectively	1,431	1,424
Additional paid-in capital	2,826,475	2,776,197
Deferred compensation payable in common shares	5,436	5,631
Common shares in grantor trust, 293,122 in 2012 and 292,646 in 2011	(5,436)	(5,631)
Cumulative earnings	493,266	477,338
Accumulated other comprehensive loss	(16,449)	(6,079)
Cumulative distributions	(1,442,662)	(1,392,332)
Total Brandywine Realty Trust's equity	1,862,124	1,856,591
Non-controlling interests	31,605	33,105
Total equity	1,893,729	1,889,696
Total liabilities and equity	4,669,170	4,557,718
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Rental properties	4,639,047	4,793,080
Accumulated depreciation	(897,367)	(865,710)
Operating real estate investments, net	3,741,680	3,927,370
Construction-in-progress	57,420	25,083
Land inventory	109,564	109,008
Total real estate investments, net	3,908,664	4,061,461
Cash and cash equivalents	190,055	410
Available-for-sale securities, Current	42,072	0
Accounts receivable, net	11,445	14,718
Accrued rent receivable, net	113,380	108,101
Assets Held-for-sale, at Carrying Value	41,450	0
Investment in real estate ventures, at equity	133,292	115,807
Deferred costs, net	114,920	115,362
Intangible assets, net	57,927	70,515
Notes receivable	7,226	18,186
Other assets	48,739	53,158
Total assets	4,669,170	4,557,718
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	505,214	511,061
Unsecured credit facility	0	275,500
Unsecured term loans	600,000	37,500
Unsecured senior notes, net of discounts	1,404,627	1,569,934
Accounts payable and accrued expenses	57,653	69,929
Distributions payable	24,889	23,895
Deferred income, gains and rent	95,390	99,569
Acquired lease intangibles, net	31,526	35,106
Other liabilities	55,264	45,528
Liabilities of Assets Held-for-sale	878	0
Total liabilities	2,775,441	2,668,022
Commitments and contingencies (Note 17)
Redeemable limited partnership units at redemption value;
Redeemable limited partnership units at redemption value; 2,657,721 and 2,698,648 issued and outstanding in 2012 and 2011, respectively	40,106	38,370
Brandywine Realty Trust's equity:
Preferred Shares		0
General Partnership Capital, 143,367,946 and 142,690,755 units issued in 2012 and 2011, respectively and 143,367,946 and 142,690,755 units outstanding in 2012 and 2011, respectively	1,717,657	1,754,302
Accumulated other comprehensive loss	(16,422)	(6,426)
Total Brandywine Realty Trust's equity	1,853,623	1,851,326
Total liabilities and equity	4,669,170	4,557,718
7.50% Series D Preferred Shares | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred Shares	0	47,912
7.50% Series C Preferred Shares
Brandywine Realty Trust's equity:
Preferred Shares	0	20
7.375% Series D Preferred Shares
Brandywine Realty Trust's equity:
Preferred Shares	23	23
Total equity	63	43
6.90% Series E Preferred Stock [Member]
Brandywine Realty Trust's equity:
Preferred Shares	40	0
6.90% Series E Preferred Stock [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred Shares	55,538	55,538
6.90% Series E-linked Preferred Stock [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred Shares	$ 96,850