Segment Information - Schedule of Segment's Contribution to Consolidated Revenues and Net Operating Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting Information [Line Items]
Other	$ 274	$ 223	$ 587	$ 442
Revenues	95,431	95,026	188,862	188,538
Consolidated property net operating income	53,645	53,008	106,640	105,705
Interest income	43	4	124	16
Other revenues	274	223	587	442
Depreciation	(21,418)	(20,829)	(42,675)	(42,596)
Interest expense	(7,753)	(10,433)	(15,846)	(21,677)
Amortization of deferred financing costs	(433)	(620)	(882)	(1,265)
General and administrative	(4,353)	(3,966)	(9,367)	(8,094)
Investment and development	(275)	(794)	(510)	(1,605)
Other investment costs	(154)	(210)	(288)	(483)
Other expenses	0	(502)	0	(1,409)
Equity in income of unconsolidated real estate entities, net	568	501	965	986
Gains on sales of real estate assets, net	(298)	36,092	1,475	36,902
Other income (expense), net	(195)	(196)	(390)	(391)
Net loss on extinguishment of indebtedness	0	(4,287)	(197)	(4,287)
Net income	19,651	47,991	39,636	62,244
Fully Stabilized Communities [Member]
Segment Reporting Information [Line Items]
Revenues	84,401	82,109	167,098	162,899
Consolidated property net operating income	50,981	49,547	101,312	99,293
Newly Stabilized Communities [Member]
Segment Reporting Information [Line Items]
Revenues	4,260	2,419	8,419	4,277
Consolidated property net operating income	2,683	1,211	5,290	1,985
Lease Up Communities [Member]
Segment Reporting Information [Line Items]
Revenues	1,096	213	2,118	233
Consolidated property net operating income	376	(168)	902	(268)
Held For Sale And Sold Communities [Member]
Segment Reporting Information [Line Items]
Revenues	0	4,820	0	10,689
Consolidated property net operating income	0	2,574	0	5,346
Other Property Segments, Including Corporate Management Expenses [Member]
Segment Reporting Information [Line Items]
Revenues	5,400	5,242	10,640	9,998
Consolidated property net operating income	$ (395)	$ (156)	$ (864)	$ (651)