Annual report pursuant to Section 13 and 15(d)

Organization - Additional Information (Detail)

v3.8.0.1
Organization - Additional Information (Detail)
12 Months Ended
Dec. 31, 2017
Property
State
Organization [Line Items]  
Number of self-storage properties owned and managed 706
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 42
Number of leased properties 2
Geographic Concentration Risk | Texas [Member] | Sales Revenue, Net  
Organization [Line Items]  
Concentration risk, percentage 23.00%
Geographic Concentration Risk | Florida [Member] | Sales Revenue, Net  
Organization [Line Items]  
Concentration risk, percentage 13.00%