Investments in Unconsolidated Real Estate Ventures - Schedule of Equity in Earnings of Unconsolidated Real Estate Ventures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Equity in earnings	$ 14,452	$ 15,331	$ 12,895
WICNN JV LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings	622	0	0
VRS Self Storage, LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings	3,640	3,562	2,919
PRISA Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings	2,338	2,430	1,912
Alan Jathoo JV LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings	(12)	0	0
Extra Space West Two LLC (1)
Schedule of Equity Method Investments [Line Items]
Equity in earnings	1,042	1,210	174
ESS Bristol Investments LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings	(152)	0	0
Extra Space West One LLC (1)
Schedule of Equity Method Investments [Line Items]
Equity in earnings	2,526	2,502	2,269
WCOT Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings	359	1,033	614
Extra Space Northern Properties Six LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings	1,014	918	823
Storage Portfolio I LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings	1,886	2,684	2,380
Storage Portfolio II JV LLC
Schedule of Equity Method Investments [Line Items]
Equity in earnings	79	33	0
Other minority owned stores
Schedule of Equity Method Investments [Line Items]
Equity in earnings	$ 1,110	$ 959	$ 1,804