Consolidated Balance Sheets (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Preferred Stock, Shares Authorized	20,000,000	20,000,000
Preferred Stock, Dividend Rate, Percentage	6.90%	6.90%
Preferred Stock, Par or Stated Value Per Share (USD per share)	$ 0.01	$ 0.01
Preferred Stock, Shares Issued	4,000,000	4,000,000
Preferred Stock, Shares Outstanding	4,000,000	4,000,000
Common Stock, Par or Stated Value Per Share (USD per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	400,000,000	400,000,000
Common Stock, Shares, Issued	174,688,568	179,293,160
Common Stock, Shares, Outstanding	174,688,568	179,293,160
Common Shares in Grantor Trust	745,686	384,536
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	1,535,102	1,535,102
Redeemable Limited Partnership Units Outstanding	1,535,102	1,535,102
General Partners' Capital Account, Units Issued	174,688,568	179,293,160
General Partners' Capital Account, Units Outstanding	174,688,568	179,293,160