Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data	Sep. 30, 2011	Dec. 31, 2010
Accounts receivable, allowance	$ 2,854	$ 2,945
Straight-line rent receivable, allowance	7,502	7,260
Deferred financing costs, accumulated amortization	56,105	46,407
Deferred leasing and other costs, accumulated amortization	$ 329,325	$ 269,000
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, shares authorized	5,000	5,000
Preferred shares, shares issued	3,176	3,618
Preferred shares, shares outstanding	3,176	3,618
Common shares, par value	$ 0.01	$ 0.01
Common shares, shares authorized	400,000	400,000
Common shares, shares issued	252,918	252,195
Common shares, shares outstanding	252,918	252,195