Segment Financial Information (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]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									$ 67,963	$ 40,556	$ 58,601
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax									4,596	0	(231)
Operations revenues									693,075	575,747	507,140
Operations expenses									(338,971)	(291,870)	(268,201)
Income from segment operations									354,104	283,877	238,939
Interest income									9,563	6,717	4,045
Amortization of in-place leases									(45,122)	(28,479)	0
Income from operations									213,628	177,858	172,032
Reconciliation to Net income available for Common Shares
Other revenues									7,239	6,735	6,114
General and administrative									(26,744)	(23,833)	(22,559)
Transaction costs									(180)	(18,493)	0
Interest and related amortization									(124,524)	(99,668)	(91,151)
Goodwill impairment									0	0	(3,635)
Equity in income of unconsolidated joint ventures									1,899	1,948	2,027
Consolidated income from continuing operations	29,014	21,492	6,299	17,653	3,862	1,356	11,654	25,632
Consolidated net income									74,458	42,504	60,397
Total Assets	3,398,226				3,496,101				3,398,226	3,496,101	2,048,395
Capital Improvements									75,260	62,032	48,629
Real Estate Depreciation Expense and Rental Homes									(104,917)	(84,257)	(70,952)
Rent Control Initiatives Expenses and Other									(1,456)	(2,043)	(2,200)
Property Operations segment
Segment Reporting Information [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									348,544	281,135	237,534
Operations revenues									669,270	560,883	495,150
Operations expenses									(320,726)	(279,748)	(257,616)
Income from segment operations									348,544	281,135	237,534
Interest income									3,075	3,377	3,263
Amortization of in-place leases									(44,010)	(27,707)
Income from operations									208,896	176,882	172,730
Reconciliation to Net income available for Common Shares
Total Assets	3,078,304				3,274,200				3,078,304	3,274,200	1,914,578
Capital Improvements									30,863	26,224	28,852
Real Estate Depreciation Expense and Rental Homes									(98,713)	(79,923)	(68,067)
Home Sales and Rentals Operations segment
Segment Reporting Information [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									5,560	2,742	1,405
Operations revenues									23,805	14,864	11,990
Operations expenses									(18,245)	(12,122)	(10,585)
Income from segment operations									5,560	2,742	1,405
Interest income									6,488	3,340	782
Amortization of in-place leases									(1,112)	(772)
Income from operations									4,732	976	(698)
Reconciliation to Net income available for Common Shares
Total Assets	319,922				221,901				319,922	221,901	133,817
Capital Improvements									44,397	35,808	19,777
Real Estate Depreciation Expense and Rental Homes									$ (6,204)	$ (4,334)	$ (2,885)
Maximum
Segment Reporting Information [Line Items]
Number of Reportable Segments									2