Consolidated Balance Sheets Consolidated Balance Sheets (Parentheticals) (USD $)	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 BRANDYWINE OPERATING PARTNERSHIP, L.P.	Dec. 31, 2012 BRANDYWINE OPERATING PARTNERSHIP, L.P.
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Dividend Rate, Percentage	6.90%	6.90%	6.90%	6.90%
Preferred Stock, Shares Issued	4,000,000	4,000,000	4,000,000	4,000,000
Preferred Stock, Shares Outstanding	4,000,000	4,000,000	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	200,000,000	200,000,000
Common Stock, Shares, Issued	156,703,790	143,538,733
Common Stock, Shares, Outstanding	156,703,790	143,538,733
Common shares in grantor trust	313,023	290,745
Redeemable Limited Partnership Units Issued			1,763,739	1,845,737
Redeemable Limited Partnership Units Outstanding			1,763,739	1,845,737
General Partners' Capital Account, Units Issued			156,703,790	143,538,733
General Partners' Capital Account, Units Outstanding			156,703,790	143,538,733