Investment in Joint Ventures - Company's Share of Unconsolidated Joint Ventures' Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ 972	$ 721
Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	689	538
Sovran HHF Storage Holdings II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	368	340
191 III Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	18	35
Life Storage-SERS Storage LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	62
Review Avenue Partners LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	(216)
SNL Orix Merrick, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	(16)	(246)
Iskalo Office Holdings, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments	$ 67	$ 54