Reportable Segments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Disclosure [Line Items]
Revenue for Reportable Segment	$ 184,345	$ 173,053	$ 376,633	$ 352,450
Operating Costs and Expenses	(94,232)	(88,941)	(185,740)	(173,608)
Operating Income Loss Before Depreciation And Other	90,113	84,112	190,893	178,842
Interest Income	1,819	1,957	3,725	3,735
Real Estate Depreciation Expense and Rental Homes	(27,761)	(29,313)	(55,403)	(55,333)
Amortization of Intangible Assets for Continuing Operations	(1,401)	(159)	(2,716)	(318)
Operating Income (Loss)	62,770	56,597	136,499	126,926
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, 2014 or 2013.
Corporate Interest Income	59	119	851	239
Income from other investments, net	2,628	1,624	4,229	4,104
General and Administrative Expense	(6,795)	(6,946)	(12,555)	(13,655)
Interest Expense, Debt	(28,265)	(30,377)	(56,313)	(60,500)
Extinguishment of Debt, Amount	0	(1,381)	0	(1,381)
Rent Control Initiatives Expenses and Other	(1,001)	(1,624)	(1,312)	(1,856)
Equity income from unconsolidated joint ventures	644	609	2,531	1,185
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax	0	3,165	0	6,233
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0	0	0	958
Consolidated net income	30,040	21,786	73,930	62,253
Total Assets	3,430,424	3,521,129	3,430,424	3,521,129	3,392,309
Capital improvements			26,534	35,850
Assets of Disposal Group, Including Discontinued Operation		120,049		120,049
Maximum [Member]
Segment Reporting Disclosure [Line Items]
Number of reportable segments			2
Property Operations Segment [Member]
Segment Reporting Disclosure [Line Items]
Revenue for Reportable Segment	173,754	164,940	356,813	337,930
Operating Costs and Expenses	(85,810)	(83,081)	(169,473)	(162,570)
Operating Income Loss Before Depreciation And Other	87,944	81,859	187,340	175,360
Interest Income	774	932	1,571	1,733
Real Estate Depreciation Expense and Rental Homes	(24,948)	(27,599)	(49,806)	(51,975)
Amortization of Intangible Assets for Continuing Operations	(1,401)	(159)	(2,716)	(318)
Operating Income (Loss)	62,369	55,033	136,389	124,800
Total Assets	3,143,600		3,143,600
Capital improvements			13,519	13,571
Home Sales And Rentals [Member]
Segment Reporting Disclosure [Line Items]
Revenue for Reportable Segment	10,591	8,113	19,820	14,520
Operating Costs and Expenses	(8,422)	(5,860)	(16,267)	(11,038)
Operating Income Loss Before Depreciation And Other	2,169	2,253	3,553	3,482
Interest Income	1,045	1,025	2,154	2,002
Real Estate Depreciation Expense and Rental Homes	(2,813)	(1,714)	(5,597)	(3,358)
Amortization of Intangible Assets for Continuing Operations	0	0	0	0
Operating Income (Loss)	401	1,564	110	2,126
Total Assets	286,824		286,824
Capital improvements			13,015	22,279
Segment, Continuing Operations [Member]
Segment Reporting Disclosure [Line Items]
Total Assets		3,401,080		3,401,080
Segment, Continuing Operations [Member] | Property Operations Segment [Member]
Segment Reporting Disclosure [Line Items]
Total Assets		3,104,484		3,104,484
Segment, Continuing Operations [Member] | Home Sales And Rentals [Member]
Segment Reporting Disclosure [Line Items]
Total Assets		$ 296,596		$ 296,596