Real Estate Assets - Additional Information (Details) - ft²	1 Months Ended	9 Months Ended
	Jan. 31, 2018	Sep. 30, 2018
Merrillville, IN
Real Estate Properties [Line Items]
Expansion completion date		2018-01
Gross square feet of traditional drive-up storage units and all-climate-controlled units	13,300
Millbrook, NY
Real Estate Properties [Line Items]
Gross square feet of traditional drive-up storage units and all-climate-controlled units		16,500
Estimate for expansion relating to construction cost		The planning for the Millbrook, NY expansion is under development and the Company is actively evaluating proposals for its construction. As of September 30, 2018, development costs for these projects have been capitalized while the projects that are under construction and are reflected in real estate assets, net on the Company’s consolidated balance sheet.