Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Real estate investments:
Rental properties	$ 4,726,169	$ 4,793,080
Accumulated depreciation	(954,665)	(865,710)
Operating real estate investments, net	3,771,504	3,927,370
Construction-in-progress	48,950	25,083
Land inventory	102,439	109,008
Total real estate investments, net	3,922,893	4,061,461
Cash and cash equivalents	1,549	410
Accounts receivable, net	13,232	14,718
Accrued rent receivable, net	122,066	108,101
Investment in real estate ventures, at equity	193,555	115,807
Deferred costs, net	122,243	115,362
Intangible Assets, net	70,620	70,515
Notes receivable	7,226	18,186
Other Assets	53,325	53,158
Total assets	4,506,709	4,557,718
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	442,974	511,061
Unsecured credit facility	69,000	275,500
Unsecured term loans	450,000	37,500
Unsecured senior notes, net of discounts	1,503,356	1,569,934
Accounts payable and accrued expenses	71,579	69,929
Distributions payable	23,652	23,895
Deferred income, gains and rent	82,947	99,569
Acquired lease intangibles, net	33,859	35,106
Other liabilities	55,826	45,528
Total liabilities	2,733,193	2,668,022
Commitments and contingencies (Note 20)
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; 143,538,733 and 142,690,755 issued and outstanding in 2012 and 2011, respectively	1,434	1,424
Additional paid-in capital	2,780,194	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	479,734	477,338
Accumulated other comprehensive loss	(15,918)	(6,079)
Cumulative distributions	(1,493,206)	(1,392,332)
Total Brandywine Realty Trust's equity	1,752,278	1,856,591
Non-controlling interests	21,238	33,105
Total equity	1,773,516	1,889,696
Total liabilities and equity	4,506,709	4,557,718
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Real estate investments:
Rental properties	4,726,169	4,793,080
Accumulated depreciation	(954,665)	(865,710)
Operating real estate investments, net	3,771,504	3,927,370
Construction-in-progress	48,950	25,083
Land inventory	102,439	109,008
Total real estate investments, net	3,922,893	4,061,461
Cash and cash equivalents	1,549	410
Accounts receivable, net	13,232	14,718
Accrued rent receivable, net	122,066	108,101
Investment in real estate ventures, at equity	193,555	115,807
Deferred costs, net	122,243	115,362
Intangible Assets, net	70,620	70,515
Notes receivable	7,226	18,186
Other Assets	53,325	53,158
Total assets	4,506,709	4,557,718
LIABILITIES AND BENEFICIARIES' EQUITY
Mortgage notes payable	442,974	511,061
Unsecured credit facility	69,000	275,500
Unsecured term loans	450,000	37,500
Unsecured senior notes, net of discounts	1,503,356	1,569,934
Accounts payable and accrued expenses	71,579	69,929
Distributions payable	23,652	23,895
Deferred income, gains and rent	82,947	99,569
Acquired lease intangibles, net	33,859	35,106
Other liabilities	55,826	45,528
Total liabilities	2,733,193	2,668,022
Commitments and contingencies (Note 20)
Redeemable limited partnership units at redemption value;
Redeemable limited partnership units at redemption value; 1,845,737 and 2,698,648 issued and outstanding in 2012 and 2011, respectively	26,777	38,370
Brandywine Realty Trust's equity:
General Partnership Capital, 143,538,733 and 142,690,755 units issued and outstanding in 2012 and 2011, respectively	1,666,341	1,754,302
Accumulated other comprehensive loss	(16,452)	(6,426)
Total Brandywine Realty Trust's equity	1,746,739	1,851,326
Total liabilities and equity	4,506,709	4,557,718
7.50% Series D Preferred Mirror Units | 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	0	23
7.375% Series D Preferred Shares | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Total equity	0	47,912
6.90% Series E Preferred Stock [Member]
Brandywine Realty Trust's equity:
Preferred Shares	40	0
Total equity	40	43
6.90% Series E Preferred Stock [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred Shares	0	55,538
Total equity	0	55,538
Series E-linked Preferred Stock [Member] | BRANDYWINE OPERATING PARTNERSHIP, L.P.
Brandywine Realty Trust's equity:
Preferred Shares	96,850	0
Total equity	$ 96,850	$ 0