Segment Information - Schedule of Segment's Contribution to Consolidated Revenues and Net Operating Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information [Line Items]
Other revenues									$ 850	$ 918	$ 995
Revenues	86,101	86,374	82,160	80,276	77,749	78,612	75,424	73,531	334,911	305,316	285,138
Consolidated property net operating income									190,383	171,988	152,765
Interest income									393	1,021	841
Other revenues									850	918	995
Depreciation									(80,145)	(75,263)	(74,497)
Interest expense									(46,419)	(56,791)	(54,613)
Amortization of deferred financing costs									(2,695)	(2,797)	(2,987)
General and administrative									(16,342)	(16,100)	(16,443)
Investment and development									(1,317)	(1,161)	(2,415)
Other investment costs									(1,401)	(1,435)	(2,417)
Impairment Charge											(35,091)
Gains on condominium sales activities, net									36,273	10,514	6,161
Equity in income of unconsolidated real estate entities, net									7,995	1,001	18,739
Other income, net									1,034	619	(874)
Net gain (loss) on extinguishment of indebtedness									(4,318)	(6,919)	2,845
Net income (loss)	18,934	22,322	21,170	21,865	3,920	8,828	9,834	3,013	84,291	25,595	(6,991)
Fully Stabilized Communities [Member]
Segment Reporting Information [Line Items]
Revenues									302,132	282,376	263,394
Consolidated property net operating income									186,343	171,499	153,767
Development And Lease-Up Communities [Member]
Segment Reporting Information [Line Items]
Revenues									1,779
Consolidated property net operating income									(5)
Acquired Communities [Member]
Segment Reporting Information [Line Items]
Revenues									7,101	117
Consolidated property net operating income									4,207	70
Other Property Segments, Including Corporate Management Expenses [Member]
Segment Reporting Information [Line Items]
Revenues									23,049	21,905	20,749
Consolidated property net operating income									$ (162)	$ 419	$ (1,002)