Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands													12 Months Ended
	Jan. 12, 2018	Oct. 13, 2017	Jul. 14, 2017	Apr. 14, 2017	Jan. 13, 2017	Oct. 14, 2016	Jul. 08, 2016	Apr. 08, 2016	Jan. 08, 2016	Oct. 09, 2015	Jul. 10, 2015	Apr. 10, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Accounting Policies [Line Items]
Cash and cash equivalents, restricted cash													$ 5,300	$ 5,300
Accumulated amortization for deferred financing costs													33,900	31,400
Intangibles including goodwill													12,100	12,100
Intangible assets													4,300	4,300
Goodwill													7,800	7,800
Accumulated amortization of identified intangible assets													2,900	2,800
Amortization of in-place leases													2,231	3,373	$ 2,358
Long-term debt													2,193,700	2,110,200
Deferred revenue, estimated period of recognition															31 years
Private REIT Subsidiaries preferred stock													68,088	$ 73,304
Operating loss carryforwards													13,000
Net investment in real estate U.S federal tax basis													3,200,000
Net investment in notes receivable U.S federal tax basis													$ 51,200
Tax status of Common Shares distributions deemed paid during the year:
Ordinary income (usd per share)													$ 1.657	$ 1.471	$ 1.169
Long-term Capital Gain													0.718	0.000	0.000
Nondividend distributions (usd per share)													0.000	0.179	0.081
Distributions declared per Common Share outstanding (usd per share)													$ 2.375	$ 1.650	$ 1.250
Quarterly distribution paid per common share (usd per share)		$ 0.487500	$ 0.487500	$ 0.487500	$ 0.425000	$ 0.425000	$ 0.425000	$ 0.425000	$ 0.375000	$ 0.375000	$ 0.375000	$ 0.375000
Preferred Stock
Significant Accounting Policies [Line Items]
Private REIT Subsidiaries preferred stock													$ 100
Fair Value, Inputs, Level 2
Significant Accounting Policies [Line Items]
Mortgage notes payable, fair value													2,184,000	$ 2,100,000
Identified Intangible Assets
Significant Accounting Policies [Line Items]
Amortization of in-place leases													$ 100	200	$ 400
New Manufactured Home
Significant Accounting Policies [Line Items]
Estimated useful life (in years)													25 years
Buildings and structural and land improvements
Significant Accounting Policies [Line Items]
Estimated useful life (in years)													30 years
Building Improvements
Significant Accounting Policies [Line Items]
Estimated useful life (in years)													10 years
Furniture, Fixtures and Equipment
Significant Accounting Policies [Line Items]
Estimated useful life (in years)													5 years
Maximum
Significant Accounting Policies [Line Items]
Investment percentage to apply cost method accounting, maximum (in percentage)													5.00%
Maximum | Used Manufactured Home
Significant Accounting Policies [Line Items]
Estimated useful life (in years)													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 (in years)													10 years
Variable Interest Entity, Primary Beneficiary
Significant Accounting Policies [Line Items]
Ownership percentage (in percentage)													93.80%
Subsequent Event
Tax status of Common Shares distributions deemed paid during the year:
Quarterly distribution paid per common share (usd per share)	$ 0.4875
Other income and expense
Tax status of Common Shares distributions deemed paid during the year:
Litigation settlement														2,400
Domestic Tax Authority
Significant Accounting Policies [Line Items]
Operating loss carryforwards													$ 75,000	$ 88,100