Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	1 Months Ended	6 Months Ended
	Mar. 04, 2011	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Aug. 14, 2008
Significant Accounting Policies [Line Items]
Intangible assets and goodwill		$ 15,900,000		$ 15,900,000
Intangible assets		8,100,000		8,100,000
Goodwill		7,800,000		7,800,000
Accumulated amortization of identified intangible assets		2,500,000		1,600,000
Cash and cash equivalents, Restricted cash		3,800,000		3,000,000
Accumulated amortization for deferred costs		13,000,000		12,600,000
Provision for uncollectable Rent Receivables		3,600,000		3,000,000
Contract Receivables, fair value					19,600,000
Contract Receivables		2,200,000		4,100,000
Proceeds from insurance carriers		11,700,000
Gain on insurance recovery, net		400,000	400,000
Contingent legal fees		100,000	200,000
Right-to-use contract, description of amortization method		For example, the Company has currently estimated that 7.9% of customers who enter a new right-to-use contract will terminate their contract after five years. Therefore, the upfront nonrefundable payments from 7.9% of the contracts entered in any particular period are amortized on a straight-line basis over a period of five years as five years is the estimated customer life for 7.9% of the Company’s customers who enter a contract.
Deferred revenue, estimated period of recognition		Right-to-use annual payments by customers under the terms of the right-to-use contracts are recognized ratably over a one-year period.
8.034% Series A Cumulative Redeemable Perpetual Preferred Stock, shares issue	8,000,000	8,000,000		0
8.034% Series A Cumulative Redeemable Perpetual Preferred Stock, par value per share	$ 0.01	$ 0.01		$ 0.01
8.034% Series A Cumulative Redeemable Perpetual Preferred Stock, liquidation preference	$ 25.00
8.034% Series A Cumulative Redeemable Perpetual Preferred Stock, dividend rate	8.034%
8.034% Series A Cumulative Redeemable Perpetual Preferred Stock, conversion Price per share	$ 24.75
Non-controlling interests - Perpetual Preferred OP Units	200,000,000			200,000,000
8.034% Series A Cumulative Redeemable Perpetual Preferred Stock, redemption price	$ 25.00
Land and Building
Significant Accounting Policies [Line Items]
Estimated useful life		30
Building Improvements
Significant Accounting Policies [Line Items]
Estimated useful life		10
Furniture, Fixtures and Equipment
Significant Accounting Policies [Line Items]
Estimated useful life		5
Real Estate
Significant Accounting Policies [Line Items]
Estimated useful life		20
Rental units, Salvage value		40.00%
Maximum
Significant Accounting Policies [Line Items]
Investment percentage to apply cost method accounting, maximum		5.00%
Rental income recognition period		1.0
Deferred revenue, estimated period of recognition		31
Minimum
Significant Accounting Policies [Line Items]
Deferred revenue, estimated period of recognition		1
Right-to-use properties contract, term		1y
Fair Value, Inputs, Level 1 | US Treasury Bill Securities
Significant Accounting Policies [Line Items]
Held to maturity securities at fair value				52,300,000
Natural Disasters and Other Casualty Events
Significant Accounting Policies [Line Items]
Estimated claims from hurricanes		$ 21,000,000
Number of properties suffered from hurricanes damage		70