Consolidated Balance Sheets (Parentheticals) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Dividend Rate, Percentage	6.90%	6.90%
Preferred Stock, Shares Issued	4,000,000	4,000,000
Preferred Stock, Shares Outstanding	4,000,000	4,000,000
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	400,000,000	200,000,000
Common Stock, Shares, Issued	178,982,369	156,731,993
Common Stock, Shares, Outstanding	178,982,369	156,731,993
Common shares in grantor trust	384,536	312,280
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Preferred Stock, Dividend Rate, Percentage	6.90%	6.90%
Preferred Stock, Shares Issued	4,000,000	4,000,000
Preferred Stock, Shares Outstanding	4,000,000	4,000,000
Redeemable Limited Partnership Units Issued	1,721,905	1,763,739
Redeemable Limited Partnership Units Outstanding	1,721,905	1,763,739
General Partners' Capital Account, Units Issued	178,982,369	156,731,993
General Partners' Capital Account, Units Outstanding	178,982,369	156,731,993