Beneficiaries Equity of the Parent Company (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Equity [Abstract]
Stock Issued During Period, Shares, New Issues			21,850,000
Numerator
Income (Loss) from Continuing Operations, Basic	$ 8,885	$ 11,147	$ 7,893	$ 18,212
Income (Loss) From Continuing Operations, Diluted	8,885	11,147	7,893	18,212
Noncontrolling Interest in Net Income (Loss) Limited Partnerships, Redeemable	84	106	35	143
Net income attributable to non-controlling interest — partners' share of consolidated real estate ventures	(24)	0	(12)	0
Noncontrolling Interest in Net Income (Loss) Joint Venture Partners, Redeemable, Diluted	(24)	0	(12)	0
Nonfofeitbale dividends allocated to unvested restricted shareholders	82	85	268	278
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted	82	85	268	278
Preferred share/unit dividends, Basic	(1,725)	(1,725)	(5,175)	(5,175)
Preferred share/unit dividends, Diluted	(1,725)	(1,725)	(5,175)	(5,175)
Income (Loss) from continuing operations available to common unitholders, Basic	6,970	9,231	2,403	12,616
Income (Loss) from continuing operations available to common unitholders, Diluted	6,970	9,231	2,403	12,616
Income (Loss) from Discontinued Operations	(3)	(59)	918	3,975
Income (Loss) From Discontinued Operations, Diluted	(3)	(59)	918	3,975
Net (income) loss from discontinued operations attributable to non-controlling interests — LP units	0	1	(10)	(52)
Discontinued Operations Attributable to Noncontrolling Interests- Diluted	0	1	(10)	(52)
Discontinued operations attributable to common shareholders, Basic	(3)	(58)	908	3,923
Discontinued operations attributable to common shareholders, Diluted	(3)	(58)	908	3,923
Net income (loss) attributable to Common Shareholders of Brandywine Realty Trust	6,967	9,173	3,311	16,539
Net Income (Loss) Available to Common Shareholders/unitholders, Diluted	$ 6,967	$ 9,173	$ 3,311	$ 16,539
Denominator
Weighted Average Number of Shares Outstanding, Basic	171,606,722	156,703,348	161,866,955	151,933,441
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	1,587,148	1,288,734	1,487,015	1,209,384
Weighted Average Number of Shares Outstanding, Diluted	173,193,870	157,992,082	163,353,970	153,142,825
Earnings per common share from continuing operations Abstract
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Basic Share	$ 0.04	$ 0.06	$ 0.01	$ 0.08
Income (Loss) from Continuing Operations Attributable to Common Shareholders/unitholders, Per Diluted Share	$ 0.04	$ 0.06	$ 0.01	$ 0.08
Discontinued Operations attributable to common shareholders/unitholders, Basic	$ 0.00	$ 0.00	$ 0.01	$ 0.03
Discontinued Operations attributable to common shareholders/unitholders, Diluted	$ 0.00	$ 0.00	$ 0.01	$ 0.03
Net income (loss) attributable to common shareholders/unitholders, Basic	$ 0.04	$ 0.06	$ 0.02	$ 0.11
Net income attributable to common shareholders/unitholders, Diluted	$ 0.04	$ 0.06	$ 0.02	$ 0.11