Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts receivable, allowance	$ 1,653	$ 3,467
Accrued rent receivable, allowance	$ 11,266	$ 13,645
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 and Outstanding	176,873,324	178,285,236
Common Shares in Grantor Trust, Issued and Outstanding	977,120	894,736
BRANDYWINE OPERATING PARTNERSHIP, L.P.
Accounts receivable, allowance	$ 1,653	$ 3,467
Accrued rent receivable, allowance	$ 11,266	$ 13,645
Redeemable Limited Partnership Units Issued and Outstanding	982,871	1,479,799
General Partners' Capital Account, Units Issued and Outstanding	176,873,324	178,285,236