Schedule II Valuation and Qualifying Accounts Schedule II Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Allowance for Uncollectible Tenant Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 2,590		$ 2,819		$ 3,063
Charged to Costs and Expenses	(42)	[1]	923	[1]	16	[1]
Deductions	33		(1,152)		(260)
Balance at End of Period	2,581		2,590		2,819
Allowance for Unbilled Deferred Rent [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	3,406		3,831		6,388
Charged to Costs and Expenses	0	[1]	(279)	[1]	(1,079)	[1]
Deductions	(799)		(146)		(1,478)
Balance at End of Period	$ 2,607		$ 3,406		$ 3,831

[1] Includes amounts reported in Discontinued Operations (see Note 17).