Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Real estate investments:
Rental properties	$ 4,660,289	$ 4,793,080
Accumulated depreciation	(925,342)	(865,710)
Operating real estate investments, net	3,734,947	3,927,370
Construction-in-progress	43,449	25,083
Land inventory	95,500	109,008
Total real estate investments, net	3,873,896	4,061,461
Cash and cash equivalents	241,616	410
Accounts receivable, net	13,394	14,718
Accrued rent receivable, net	117,306	108,101
Investment in real estate ventures, at equity	179,037	115,807
Deferred costs, net	119,182	115,362
Intangible Assets, net	52,575	70,515
Notes receivable	7,226	18,186
Other assets	62,494	53,158
Total assets	4,666,726	4,557,718
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	502,123	511,061
Unsecured credit facility	0	275,500
Unsecured term loans	600,000	37,500
Unsecured senior notes, net of discounts	1,404,466	1,569,934
Accounts payable and accrued expenses	80,554	69,929
Distributions payable	24,820	23,895
Deferred income, gains and rent	80,748	99,569
Acquired lease intangibles, net	29,824	35,106
Other liabilities	59,982	45,528
Total liabilities	2,782,517	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; 143,438,501 and 142,690,755 issued and outstanding in 2012 and 2011, respectively	1,432	1,424
Additional paid-in capital	2,828,722	2,776,197
Deferred compensation payable in common shares	5,352	5,631
Common shares in grantor trust, 290,745 in 2012 and 292,646 in 2011	(5,352)	(5,631)
Cumulative earnings	510,093	477,338
Accumulated other comprehensive loss	(20,456)	(6,079)
Cumulative distributions	(1,467,058)	(1,392,332)
Total Brandywine Realty Trust's equity	1,852,796	1,856,591
Non-controlling interests	31,413	33,105
Total equity	1,884,209	1,889,696
Total liabilities and equity	4,666,726	4,557,718
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Rental properties	4,660,289	4,793,080
Accumulated depreciation	(925,342)	(865,710)
Operating real estate investments, net	3,734,947	3,927,370
Construction-in-progress	43,449	25,083
Land inventory	95,500	109,008
Total real estate investments, net	3,873,896	4,061,461
Cash and cash equivalents	241,616	410
Accounts receivable, net	13,394	14,718
Accrued rent receivable, net	117,306	108,101
Investment in real estate ventures, at equity	179,037	115,807
Deferred costs, net	119,182	115,362
Intangible Assets, net	52,575	70,515
Notes receivable	7,226	18,186
Other assets	62,494	53,158
Total assets	4,666,726	4,557,718
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	502,123	511,061
Unsecured credit facility	0	275,500
Unsecured term loans	600,000	37,500
Unsecured senior notes, net of discounts	1,404,466	1,569,934
Accounts payable and accrued expenses	80,554	69,929
Distributions payable	24,820	23,895
Deferred income, gains and rent	80,748	99,569
Acquired lease intangibles, net	29,824	35,106
Other liabilities	59,982	45,528
Total liabilities	2,782,517	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	40,509	38,370
Brandywine Realty Trust's equity:
General Partnership Capital, 143,438,501 and 142,690,755 units issued and outstanding in 2012 and 2011, respectively	1,711,926	1,754,302
Accumulated other comprehensive loss	(20,614)	(6,426)
Total Brandywine Realty Trust's equity	1,843,700	1,851,326
Total liabilities and equity	4,666,726	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	$ 0