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	Dec. 31, 2008
Allowance for Tenant Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance, beginning of year	$ 1,760	$ 3,167		$ 3,101
Additions in allowances charged to expense	1,523	1,682	2,726
Transfer	0	(1,400)	0
Bad debts charged against allowance	(1,306)	(1,689)	(2,660)
Balance, end of year	1,977	1,760	3,167	3,101
Allowance for Other Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance, beginning of year	1,400	0	0
Transfer	0	1,400	0
Bad debts charged against allowance	130	0	0
Balance, end of year	$ 1,270	$ 1,400	$ 0