Investment in Joint Ventures - Summary of Unconsolidated Joint Ventures' Financial Statements (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Investment in storage facilities, net	$ 1,585,374		$ 1,498,165
Other assets	7,367		11,021
Total Assets	1,643,008		1,561,875
Mortgages payable	2,223		2,254
Total Liabilities	736,140		678,226
Depreciation and amortization of customer list	(11,942)	(11,202)
Amortization of financing fees	(195)	(209)
Income tax expense	(300)	(300)
Interest expense	(7,343)	(8,457)
Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Investment in storage facilities, net	157,109
Investment in office building
Other assets	5,580
Total Assets	162,689
Due to the Company	504
Mortgages payable	81,680
Other liabilities	2,515
Total Liabilities	84,699
Unaffiliated partners' equity (deficiency)	62,392
Company equity (deficiency)	15,598
Total Partners' Equity (Deficiency)	77,990
Total Liabilities and Partners' Equity (Deficiency)	162,689
Total revenues	5,452
Property operating expenses	(1,793)
Administrative, management and call center fees	(415)
Depreciation and amortization of customer list	(962)
Amortization of financing fees	(46)
Income tax expense	(22)
Interest expense	(1,073)
Net income	1,141
Sovran HHF Storage Holdings II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Investment in storage facilities, net	186,985
Investment in office building
Other assets	4,803
Total Assets	191,788
Due to the Company	362
Mortgages payable	103,424
Other liabilities	2,200
Total Liabilities	105,986
Unaffiliated partners' equity (deficiency)	72,937
Company equity (deficiency)	12,865
Total Partners' Equity (Deficiency)	85,802
Total Liabilities and Partners' Equity (Deficiency)	191,788
Total revenues	6,887
Property operating expenses	(2,596)
Administrative, management and call center fees	(512)
Depreciation and amortization of customer list	(1,036)
Amortization of financing fees	(51)
Income tax expense	(100)
Interest expense	(1,272)
Net income	1,320
Iskalo Office Holdings, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Investment in storage facilities, net
Investment in office building	4,899
Other assets	669
Total Assets	5,568
Due to the Company
Mortgages payable	6,391
Other liabilities	609
Total Liabilities	7,000
Unaffiliated partners' equity (deficiency)	(954)
Company equity (deficiency)	(478)
Total Partners' Equity (Deficiency)	(1,432)
Total Liabilities and Partners' Equity (Deficiency)	5,568
Total revenues	364
Property operating expenses	(141)
Administrative, management and call center fees
Depreciation and amortization of customer list	(57)
Amortization of financing fees	(3)
Income tax expense
Interest expense	(97)
Net income	$ 66