Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Real estate investments:
Rental properties	$ 4,717,124	$ 4,793,080
Accumulated depreciation	(884,026)	(865,710)
Operating real estate investments, net	3,833,098	3,927,370
Construction-in-progress	38,442	25,083
Land inventory	109,285	109,008
Total real estate investments, net	3,980,825	4,061,461
Cash and cash equivalents	284,236	410
Held-to-maturity securities	50,164	0
Accounts receivable, net	14,038	14,718
Accrued rent receivable, net	110,853	108,101
Investment in real estate ventures, at equity	127,536	115,807
Deferred costs, net	118,685	115,362
Intangible assets, net	63,969	70,515
Notes receivable	17,991	18,186
Other assets	57,046	53,158
Total assets	4,825,343	4,557,718
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	508,210	511,061
Unsecured credit facility	0	275,500
Unsecured term loans	600,000	37,500
Unsecured senior notes, net of discounts	1,566,240	1,569,934
Accounts payable and accrued expenses	72,832	69,929
Distributions payable	23,860	23,895
Deferred income, gains and rent	99,905	99,569
Acquired lease intangibles, net	33,278	35,106
Other liabilities	45,576	45,528
Total liabilities	2,949,901	2,668,022
Commitments and contingencies (Note 17)
Brandywine Realty Trust's equity:
Common Shares of Brandywine Realty Trust’s beneficial interest, $0.01 par value; shares authorized 200,000,000; 143,022,150 and 142,690,755 issued in 2012 and 2011, respectively and 143,022,150 and 142,690,755 outstanding in 2012 and 2011, respectively	1,428	1,424
Additional paid-in capital	2,777,148	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	486,491	477,338
Accumulated other comprehensive loss	(6,005)	(6,079)
Cumulative distributions	(1,415,916)	(1,392,332)
Total Brandywine Realty Trust's equity	1,843,189	1,856,591
Non-controlling interests	32,253	33,105
Total equity	1,875,442	1,889,696
Total liabilities and equity	4,825,343	4,557,718
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Rental properties	4,717,124	4,793,080
Accumulated depreciation	(884,026)	(865,710)
Operating real estate investments, net	3,833,098	3,927,370
Construction-in-progress	38,442	25,083
Land inventory	109,285	109,008
Total real estate investments, net	3,980,825	4,061,461
Cash and cash equivalents	284,236	410
Held-to-maturity securities	50,164	0
Accounts receivable, net	14,038	14,718
Accrued rent receivable, net	110,853	108,101
Investment in real estate ventures, at equity	127,536	115,807
Deferred costs, net	118,685	115,362
Intangible assets, net	63,969	70,515
Notes receivable	17,991	18,186
Other assets	57,046	53,158
Total assets	4,825,343	4,557,718
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	508,210	511,061
Unsecured credit facility	0	275,500
Unsecured term loans	600,000	37,500
Unsecured senior notes, net of discounts	1,566,240	1,569,934
Accounts payable and accrued expenses	72,832	69,929
Distributions payable	23,860	23,895
Deferred income, gains and rent	99,905	99,569
Acquired lease intangibles, net	33,278	35,106
Other liabilities	45,576	45,528
Total liabilities	2,949,901	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	39,785	38,370
Brandywine Realty Trust's equity:
General Partnership Capital, 143,022,150 and 142,690,755 units issued in 2012 and 2011, respectively and 143,022,150 and 142,690,755 units outstanding in 2012 and 2011, respectively	1,738,348	1,754,302
Accumulated other comprehensive loss	(6,141)	(6,426)
Total Brandywine Realty Trust's equity	1,835,657	1,851,326
Total liabilities and equity	4,825,343	4,557,718
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
7.375% Series E Preferred Shares | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred Shares	$ 55,538	$ 55,538