Reportable Segments Reportable Segments (Revenue Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Document Fiscal Year Focus				2015
Rental property operating expenses	$ (41,387)	$ (35,959)		$ (79,340)	$ (70,816)
Total consolidated revenues	97,903	84,505		189,879	166,228
Total Segment [Member]
Segment Reporting Information [Line Items]
Net operating property income, including discontinued operations	60,774	51,288	$ 51,288	118,827	101,306	$ 101,306	$ 118,827
Residential Lot Sales Net of Cost of Sales Including Gain on Sale of Undepreciated Investment Properties	(324)	1,373	1,373	486	1,533	1,533	486
Fee income, Net of Reimbursed Expenses	1,704	2,025	2,025	3,520	4,363	4,363	3,520
Other Income	238	$ 2,256	2,256	$ 645	$ 4,172	4,172	645
Rental property operating expenses			35,959			(70,816)
Plus residential lot, multi-family unit and outparcel cost of sales	0		270			(270)	0
Net operating income in joint venture	(5,984)		(6,648)			(13,147)	(11,971)
Net sales of joint ventures	(242)		(47)			(47)	(242)
Net operating income from discontinued operations not included in revenues	0		(565)			(1,457)	14
Discontinued Operations Other Income	188		82			89	348
Termination Fees in Discontinues Operations and in Joint Ventures	(28)		0			0	(148)
Residential Lot Multi Family Unit Tract and Outparcel Sales Net of Cost of Sales Including Gain on Sale of Undepreciated Investment Properties	566		(1,324)			(1,492)	(244)
Total consolidated revenues	$ 97,903		$ 84,505			$ 166,228	$ 189,879