Reportable Segments - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Disclosure [Line Items]
Major customers description			All revenues are from external customers and there is no customer who contributed 10% or more of our total revenues during the quarters or six months ended June 30, 2013 or 2012.
Segment Reporting Information, Revenue for Reportable Segment	$ 173,053,000	$ 164,908,000	$ 352,450,000	$ 336,257,000
Operating Costs and Expenses	(88,941,000)	(83,875,000)	(173,608,000)	(163,645,000)
Operating Income Loss Before Depreciation And Other	84,112,000	81,033,000	178,842,000	172,612,000
Interest Income	1,957,000	1,797,000	3,735,000	3,792,000
Real Estate Depreciation Expense and Rental Homes	(29,313,000)	(25,523,000)	(55,333,000)	(50,947,000)
Amortization of Intangible Assets for Continuing Operations	(159,000)	(15,650,000)	(318,000)	(31,265,000)
Operating Income (Loss)	56,597,000	41,657,000	126,926,000	94,192,000
Gross revenue from home sales	4,217,000	1,921,000	6,913,000	3,925,000
Other Revenues	1,743,000	1,678,000	4,343,000	3,275,000
General and Administrative Expense	(6,946,000)	(6,810,000)	(13,655,000)	(12,909,000)
Interest Expense, Debt	(30,377,000)	(30,705,000)	(60,500,000)	(61,528,000)
Payments of Debt Extinguishment Costs	(1,381,000)	0	(1,381,000)	0
Rent Control Initiatives Expenses and Other	(1,624,000)	(367,000)	(1,856,000)	(846,000)
Equity income from unconsolidated joint ventures	609,000	492,000	1,185,000	1,255,000
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	3,165,000	353,000	6,233,000	513,000
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0	0	958,000	0
Consolidated net income	21,786,000	6,298,000	62,253,000	23,952,000
Total Assets	3,521,129,000	3,498,650,000	3,521,129,000	3,498,650,000	3,398,226,000
Assets of Disposal Group, Including Discontinued Operation	120,049,000	118,252,000	120,049,000	118,252,000	119,852,000
Capital improvements			35,850,000	30,560,000
Maximum
Segment Reporting Disclosure [Line Items]
Number of reportable segments			2
Property Operations Segment [Member]
Segment Reporting Disclosure [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	164,940,000	159,870,000	337,930,000	326,306,000
Operating Costs and Expenses	(83,081,000)	(79,681,000)	(162,570,000)	(155,542,000)
Operating Income Loss Before Depreciation And Other	81,859,000	80,189,000	175,360,000	170,764,000
Interest Income	932,000	782,000	1,733,000	1,636,000
Real Estate Depreciation Expense and Rental Homes	(27,599,000)	(24,149,000)	(51,975,000)	(48,257,000)
Amortization of Intangible Assets for Continuing Operations	(159,000)	(15,346,000)	(318,000)	(30,657,000)
Operating Income (Loss)	55,033,000	41,476,000	124,800,000	93,486,000
Capital improvements			13,571,000	13,349,000
Home Sales And Rentals [Member]
Segment Reporting Disclosure [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	8,113,000	5,038,000	14,520,000	9,951,000
Operating Costs and Expenses	(5,860,000)	(4,194,000)	(11,038,000)	(8,103,000)
Operating Income Loss Before Depreciation And Other	2,253,000	844,000	3,482,000	1,848,000
Interest Income	1,025,000	1,015,000	2,002,000	2,156,000
Real Estate Depreciation Expense and Rental Homes	(1,714,000)	(1,374,000)	(3,358,000)	(2,690,000)
Amortization of Intangible Assets for Continuing Operations	0	(304,000)	0	(608,000)
Operating Income (Loss)	1,564,000	181,000	2,126,000	706,000
Gross revenue from home sales	4,217,000	1,921,000	6,913,000	3,925,000
Capital improvements			22,279,000	17,211,000
Site rental income	9,800,000	7,900,000	19,200,000	15,300,000
Segment, Discontinued Operations [Member]
Segment Reporting Disclosure [Line Items]
Interest Expense, Debt	$ 131,000	$ 133,000	$ 260,000	$ 266,000