Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Accounting Policies [Line Items]
Cash and cash equivalents, restricted cash	$ 5,000				$ 5,000								$ 5,000	$ 5,000
Accumulated amortization for deferred financing costs	33,700				29,800								33,700	29,800
Intangible Assets, Net (Including Goodwill)	12,100				12,100								12,100	12,100
Intangible assets	4,300				4,300								4,300	4,300
Goodwill	7,800				7,800								7,800	7,800
Accumulated amortization of identified intangible assets	2,600				2,200								2,600	2,200
Amortization of in-place leases													2,358	3,999	$ 1,940
Long-term Debt	2,100,000				2,200,000								$ 2,100,000	2,200,000
Deferred revenue, estimated period of recognition													31 years
Private REIT Subsidiaries preferred stock	67,623				$ 67,034								$ 67,623	$ 67,034
Operating Loss Carryforwards	88,000												88,000
Net investment in real estate U.S federal tax basis	2,800,000												2,800,000
Net investment in notes receivable U.S federal tax basis	$ 38,400												$ 38,400
Tax status of Common Shares distributions [Abstract]
Ordinary Income Dividends Per Share													$ 1.169	$ 1.217	$ 0.680
Capital Gains Dividends Per Share													0.000	0.000	0.211
Nondividend Distribution													0.081	0.000	0.000
Unrecaptured Section 1250 Gain Dividends Per Share													0.000	0.000	0.067
Common Stock Dividends Per Share Tax Treatment													$ 1.250	$ 1.217	$ 0.958
Dividends Payable, Date to be Paid	Jan. 08, 2016	Oct. 09, 2015	Jul. 10, 2015	Apr. 10, 2015	Jan. 09, 2015	Oct. 10, 2014	Jul. 11, 2014	Apr. 11, 2014	Jan. 10, 2014	Oct. 11, 2013	Jul. 12, 2013	Apr. 12, 2013
Quarterly distribution paid per common share	$ 0.375	$ 0.375	$ 0.375	$ 0.375	$ 0.325	$ 0.325	$ 0.325	$ 0.325	$ 0.25	$ 0.25	$ 0.25	$ 0.25
Preferred Stock
Significant Accounting Policies [Line Items]
Private REIT Subsidiaries preferred stock	$ 300												$ 300
Florida
Significant Accounting Policies [Line Items]
Percentage of company revenue													41.00%	40.90%	40.70%
Arizona
Significant Accounting Policies [Line Items]
Percentage of company revenue													10.10%	9.60%	9.80%
California
Significant Accounting Policies [Line Items]
Percentage of company revenue													14.70%	15.20%	15.70%
Fair Value, Inputs, Level 2
Significant Accounting Policies [Line Items]
Mortgage notes payable, fair value	$ 2,200,000				$ 2,300,000								$ 2,200,000	$ 2,300,000
Identified Intangible Assets
Significant Accounting Policies [Line Items]
Amortization of in-place leases													$ 400	$ 300
Purchase Price Allocation Adjustments
Significant Accounting Policies [Line Items]
Final Adjustment Period Maximum Range													1 year
New Manufactured Home
Significant Accounting Policies [Line Items]
Estimated useful life													25 years
Buildings and structural and land improvements
Significant Accounting Policies [Line Items]
Estimated useful life													30 years
Building Improvements
Significant Accounting Policies [Line Items]
Estimated useful life													10 years
Furniture, Fixtures and Equipment
Significant Accounting Policies [Line Items]
Estimated useful life													5 years
Maximum
Significant Accounting Policies [Line Items]
Investment percentage to apply cost method accounting, maximum	5.00%												5.00%
Rental income recognition period													1 year
Maximum | Used Manufactured Home
Significant Accounting Policies [Line Items]
Estimated useful life													25 years
Minimum
Significant Accounting Policies [Line Items]
Right-to-use properties contract, term													1 year
Minimum | Used Manufactured Home
Significant Accounting Policies [Line Items]
Estimated useful life													10 years