Reportable Segments (Revenue Reconciliation) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Plus rental property operating expenses	$ (54,518)	$ (44,912)	$ (43,441)
Total consolidated revenues	148,278	129,046	154,234
Total
Segment Reporting Information [Line Items]
Net operating income	110,457	110,553	108,242
Sales less cost of sales	5,224	7,486	20,400
Fee income	34,162	33,180	33,420
Other income	5,153	2,204	1,312
Plus rental property operating expenses	54,518	44,912	43,441
Cost of sales	1,833	5,378	28,956
Net operating income in joint ventures	(23,596)	(24,258)	(20,179)
Sales less cost of sales in joint ventures	(28)	(1,927)	(6,034)
Net operating income in discontinued operations	(15,770)	(25,611)	(29,788)
Fee income in discontinued operations	(16,365)	(19,359)	(18,977)
Other income in discontinued operations	(3,591)	(254)	(193)
Gain on tract sales (included in gain on investment properties)	(3,719)	(3,258)	(6,366)
Total consolidated revenues	$ 148,278	$ 129,046	$ 154,234