Annual report pursuant to Section 13 and 15(d)

Investment in Joint Ventures - Company's Share of Unconsolidated Joint Ventures' Income (Loss) (Detail)

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Investment in Joint Ventures - Company's Share of Unconsolidated Joint Ventures' Income (Loss) (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments $ 4,122 $ 3,314 $ 3,665
Sovran HHF Storage Holdings LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments 3,285 2,517 2,033
Sovran HHF Storage Holdings II LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments 1,686 1,530 1,403
191 III Holdings LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments 89 13  
Life Storage-SERS Storage LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments 16 (12)  
Life Storage-HIERS Storage LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments 23    
Review Avenue Partners LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments (860) (967)  
SNL Orix Merrick, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments (43)    
SNL/Orix 1200 McDonald Ave., LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments (24)    
Urban Box Coralway Storage, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments (195)   15
N 32nd Street Self Storage, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments (81)    
Iskalo Office Holdings, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments $ 226 $ 233 $ 214