Segment Financial Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	$ 173,053	$ 164,908	$ 352,450	$ 336,257
Operations expenses	(88,941)	(83,875)	(173,608)	(163,645)
Operating Income Loss Before Depreciation And Other	84,112	81,033	178,842	172,612
Interest Income	1,957	1,797	3,735	3,792
Depreciation on real estate and rental homes	(29,313)	(25,523)	(55,333)	(50,947)
Amortization of Intangible Assets for Continuing Operations	(159)	(15,650)	(318)	(31,265)
Operating Income (Loss)	56,597	41,657	126,926	94,192
Reconciliation to Consolidated net income
Other Revenues	1,743	1,678	4,343	3,275
General and administrative	(6,946)	(6,810)	(13,655)	(12,909)
Interest and related amortization	(30,377)	(30,705)	(60,500)	(61,528)
Payments of Debt Extinguishment Costs	(1,381)	0	(1,381)	0
Rent control initiatives and other	(1,624)	(367)	(1,856)	(846)
Equity in income of unconsolidated joint ventures	609	492	1,185	1,255
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	3,165	353	6,233	513
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0	0	958	0
Total assets	3,521,129	3,498,650	3,521,129	3,498,650	3,398,226
Assets of Disposal Group, Including Discontinued Operation	120,049	118,252	120,049	118,252	119,852
Capital improvements			35,850	30,560
Property Operations Segment [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	164,940	159,870	337,930	326,306
Operations expenses	(83,081)	(79,681)	(162,570)	(155,542)
Operating Income Loss Before Depreciation And Other	81,859	80,189	175,360	170,764
Interest Income	932	782	1,733	1,636
Depreciation on real estate and rental homes	(27,599)	(24,149)	(51,975)	(48,257)
Amortization of Intangible Assets for Continuing Operations	(159)	(15,346)	(318)	(30,657)
Operating Income (Loss)	55,033	41,476	124,800	93,486
Reconciliation to Consolidated net income
Capital improvements			13,571	13,349
Home Sales and Rentals Operations segment
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	8,113	5,038	14,520	9,951
Operations expenses	(5,860)	(4,194)	(11,038)	(8,103)
Operating Income Loss Before Depreciation And Other	2,253	844	3,482	1,848
Interest Income	1,025	1,015	2,002	2,156
Depreciation on real estate and rental homes	(1,714)	(1,374)	(3,358)	(2,690)
Amortization of Intangible Assets for Continuing Operations	0	(304)	0	(608)
Operating Income (Loss)	1,564	181	2,126	706
Reconciliation to Consolidated net income
Capital improvements			22,279	17,211
Segment, Discontinued Operations [Member]
Reconciliation to Consolidated net income
Interest and related amortization	131	133	260	266
Segment, Continuing Operations [Member]
Reconciliation to Consolidated net income
Total assets	3,401,080	3,380,398	3,401,080	3,380,398
Segment, Continuing Operations [Member] | Property Operations Segment [Member]
Reconciliation to Consolidated net income
Total assets	3,104,484	3,175,796	3,104,484	3,175,796
Segment, Continuing Operations [Member] | Home Sales and Rentals Operations segment
Reconciliation to Consolidated net income
Total assets	$ 296,596	$ 204,602	$ 296,596	$ 204,602