Segment Information - Schedule of Segment's Contribution to Consolidated Revenues and Net Operating Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Revenues	$ 97,767	$ 96,461	$ 286,629	$ 284,999
Other	337	234	924	676
Consolidated property net operating income	54,723	54,552	161,363	160,257
Interest income	34	78	158	94
Depreciation	(22,073)	(21,018)	(64,748)	(63,614)
Interest expense	(7,927)	(9,858)	(23,773)	(31,535)
Amortization of deferred financing costs	(432)	(588)	(1,314)	(1,853)
General and administrative	(4,622)	(4,784)	(13,989)	(12,878)
Investment and development	(73)	(555)	(583)	(2,160)
Other investment costs	(165)	(224)	(453)	(707)
Other expenses		(344)		(1,753)
Equity in income of unconsolidated real estate entities, net	603	422	1,568	1,408
Gains on sales of real estate assets, net		152,785	1,475	189,687
Other income (expense), net	(215)	(195)	(605)	(586)
Net loss on extinguishment of indebtedness		(14,070)	(197)	(18,357)
Net income	20,190	156,435	59,826	218,679
Fully Stabilized Communities [Member]
Segment Reporting Information [Line Items]
Revenues	85,725	83,371	252,823	246,271
Consolidated property net operating income	52,038	50,913	153,350	150,206
Newly Stabilized Communities [Member]
Segment Reporting Information [Line Items]
Revenues	4,361	3,188	12,780	7,466
Consolidated property net operating income	2,380	1,935	7,669	3,922
Lease Up Communities [Member]
Segment Reporting Information [Line Items]
Revenues	1,404	656	3,523	889
Consolidated property net operating income	432	44	1,336	(224)
Held For Sale And Sold Communities [Member]
Segment Reporting Information [Line Items]
Revenues		3,478		14,168
Consolidated property net operating income		1,811		7,157
Other Property Segments, Including Corporate Management Expenses [Member]
Segment Reporting Information [Line Items]
Revenues	5,940	5,534	16,579	15,529
Consolidated property net operating income	$ (127)	$ (151)	$ (992)	$ (804)