Organization - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended	1 Months Ended	6 Months Ended	9 Months Ended
	Sep. 30, 2012 Property	Sep. 30, 2011	Sep. 30, 2012 Property	Sep. 30, 2011	Dec. 31, 2011	May 31, 2011 Locke Sovran II, LLC [Member]	Jun. 30, 2011 West Deptford JV LLC [Member]	Sep. 30, 2012 West Deptford JV LLC [Member] Property	Sep. 30, 2012 Sovran HHF Storage Holdings LLC [Member] Property	Sep. 30, 2012 Sovran HHF Storage Holdings II LLC [Member] Property
Organization [Line Items]
Number of self-storage properties owned and managed	443		443
Number of states in which self-storage properties owned and managed	25		25
Number of properties owned and managed under twenty-percent stake joint venture									25
Percentage ownership in unconsolidated joint venture									20.00%	15.00%
Number of properties owned and managed under fifteen-percent stake joint venture										30
Number of properties twenty-percent owned under consolidated joint venture								1
Percentage ownership in consolidated joint venture						100.00%	20.00%	20.00%
Number of properties managed with no ownership	11		11
Concentration risk, percentage			40.00%
Percentage of ownership interest of the Subsidiary and its limited partnership which controls the operations of the Operating Partnership	99.30%		99.30%
Additional investment in Locke Sovran II, LLC						$ 17,000,000
Reduction of additional paid-in capital						3,900,000
Noncontrolling interest repayment						2,800,000
Payments to noncontrolling interests						14,200,000
Payments to acquire businesses and interest in affiliates							4,200,000
Mortgage note acquired							2,800,000
Interest rate for mortgage notes acquired							8.00%
Payments to acquire preferred interest in affiliates							1,400,000
Preferred interest in investment							8.00%
Total assets	1,397,348,000		1,397,348,000		1,343,674,000			4,000,000
Total liabilities	657,966,000		657,966,000		673,669,000			2,900,000
Operating revenues	61,774,000	52,097,000	173,875,000	148,166,000				500,000
Net loss	18,807,000	2,339,000	41,666,000	20,336,000				(121,000)
Depreciation and amortization								$ 124,000
Units of redeemable noncontrolling interest in operating partnership			204,163		339,025