Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accounts and other receivables,allowance	$ 656	$ 821
Acquired above-market leases, accumulated amortization	21,344	15,729
Acquired in-place lease value, accumulated amortization	82,617	60,861
Deferred financing costs, accumulated amortization	7,020	4,189
Lease commissions, accumulated amortization	1,490	990
Notes payable, discount	2,297	2,838
Notes payable, premium	8,061	9,595
Acquired below-market leases, accumulated amortization	18,226	13,876
Above-market ground leases, obligation, accumulated amortization	71	18
Class B Interest	$ 200	$ 0
Common Shares of Beneficial Interest	$ 0.01	$ 0.01
Common Shares of Beneficial Interest, shares authorized	990,000,000	990,000,000
Common Shares of Beneficial Interest, issued	249,390,337	249,390,337
Common Shares of Beneficial Interest, outstanding	230,955,633	230,955,633