Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Real estate investments:
Rental properties	$ 4,793,080	$ 4,834,111	$ 4,512,618
Accumulated depreciation	(865,710)	(776,078)
Operating real estate investments, net	3,927,370	4,058,033
Construction-in-progress	25,083	33,322	271,962
Land inventory	109,008	110,055	97,368
Total real estate investments, net	4,061,461	4,201,410
Cash and cash equivalents	410	16,565	1,567	3,924
Accounts receivable, net	14,718	16,009
Accrued rent receivable, net	108,101	95,541
Investment in real estate ventures, at equity	115,807	84,372
Deferred costs, net	115,362	106,117
Intangible assets, net	70,515	97,462
Notes receivable	18,186	18,205
Other assets	53,158	54,697
Total assets	4,557,718	4,690,378
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	511,061	711,789
Unsecured credit facility	275,500	183,000
Unsecured term loan	37,500	183,000
Unsecured senior notes, net of discounts	1,569,934	1,352,657
Accounts payable and accrued expenses	69,929	72,235
Distributions payable	23,895	22,623
Deferred income, gains and rent	99,569	121,552
Acquired lease intangibles, net	35,106	29,233
Other liabilities	45,528	36,515
Total liabilities	2,668,022	2,712,604
Commitments and contingencies (Note 20)
Brandywine Realty Trust's equity:
Common Shares of Brandywine Realty Trust’s beneficial interest, $0.01 par value; shares authorized 200,000,000; 142,690,755 and 134,601,796 issued in 2011 and 2010, respectively and 142,690,755 and 134,485,117 outstanding in 2011 and 2010, respectively	1,424	1,343
Additional paid-in capital	2,776,197	2,671,217
Deferred compensation payable in common stock	5,631	5,774
Common shares in treasury, at cost, 116,679 in 2010		(3,074)
Common shares in grantor trust, 292,646 in 2011 and 291,281 in 2010	(5,631)	(5,774)
Cumulative earnings	477,338	483,439
Accumulated other comprehensive loss	(6,079)	(1,945)
Cumulative distributions	(1,392,332)	(1,301,521)
Total Brandywine Realty Trust's equity	1,856,591	1,849,502
Non-controlling interests	33,105	128,272
Total equity	1,889,696	1,977,774	1,921,740	1,722,498
Total liabilities and equity	4,557,718	4,690,378
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Rental properties	4,793,080	4,834,111
Accumulated depreciation	(865,710)	(776,078)
Operating real estate investments, net	3,927,370	4,058,033
Construction-in-progress	25,083	33,322
Land inventory	109,008	110,055
Total real estate investments, net	4,061,461	4,201,410
Cash and cash equivalents	410	16,565	1,567	3,924
Accounts receivable, net	14,718	16,009
Accrued rent receivable, net	108,101	95,541
Investment in real estate ventures, at equity	115,807	84,372
Deferred costs, net	115,362	106,117
Intangible assets, net	70,515	97,462
Notes receivable	18,186	18,205
Other assets	53,158	54,697
Total assets	4,557,718	4,690,378
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	511,061	711,789
Unsecured credit facility	275,500	183,000
Unsecured term loan	37,500	183,000
Unsecured senior notes, net of discounts	1,569,934	1,352,657
Accounts payable and accrued expenses	69,929	72,235
Distributions payable	23,895	22,623
Deferred income, gains and rent	99,569	121,552
Acquired lease intangibles, net	35,106	29,233
Other liabilities	45,528	36,515
Total liabilities	2,668,022	2,712,604
Commitments and contingencies (Note 20)
Redeemable limited partnership units at redemption value;
Redeemable limited partnership units at redemption value; 2,698,648 and 9,902,752 issued and outstanding in 2011 and 2010, respectively	38,370	132,855
Brandywine Realty Trust's equity:
General Partnership Capital, 142,690,755 and 134,601,796 units issued in 2011 and 2010, respectively and 142,690,755 and 134,485,117 units outstanding in 2011 and 2010, respectively	1,754,302	1,743,549
Accumulated other comprehensive loss	(6,426)	(2,080)
Total Brandywine Realty Trust's equity	1,851,326	1,844,919
Total liabilities and equity	4,557,718	4,690,378
7.50% Series D Preferred Shares | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred Shares	47,912	47,912
7.50% Series C Preferred Shares
Brandywine Realty Trust's equity:
Preferred Shares	20	20
7.375% Series D Preferred Shares
Brandywine Realty Trust's equity:
Preferred Shares	23	23
Total equity	43	43	43	43
7.375% Series D Preferred Shares | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Total equity	47,912	47,912	47,912	47,912
7.375% Series E Preferred Shares | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred Shares	55,538	55,538
Total equity	$ 55,538	$ 55,538	$ 55,538	$ 55,538