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, 2017
Dec. 31, 2016
Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments $ 3,314 $ 3,665 $ 3,405
Sovran HHF Storage Holdings LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments 2,517 2,033 1,953
Sovran HHF Storage Holdings II LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments 1,530 1,403 1,263
191 III Holdings LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments 13    
Life Storage-SERS Storage LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments (12)    
Urban Box Coralway Storage, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments   15  
Review Avenue Partners LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments (967)    
Iskalo Office Holdings, LLC [Member]      
Schedule of Equity Method Investments [Line Items]      
Income (loss) from equity method investments $ 233 $ 214 $ 189