Organization - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018 Property State shares	Dec. 31, 2017 shares
Organization [Line Items]
Percentage of ownership interest of the subsidiary and its limited partnership which controls the operations of the Operating Partnership	99.50%
Number of self-storage properties owned and managed	718
Number of states in which self-storage properties owned and managed | State	28
Number of properties managed under joint ventures	98
Number of properties managed with no ownership	54
Units of redeemable noncontrolling interest in operating partnership | shares	215,009	217,481
Noncontrolling limited partnership unit redemption value	one common share or cash
Geographic Concentration Risk [Member] | Texas [Member] | Revenue [Member]
Organization [Line Items]
Concentration risk, percentage	22.00%
Geographic Concentration Risk [Member] | Florida [Member] | Revenue [Member]
Organization [Line Items]
Concentration risk, percentage	13.00%
Life Storage Solutions, LLC [Member]
Organization [Line Items]
Percentage of ownership by subsidiary	60.00%