Real Estate Assets - Additional Information (Details) - ft²	12 Months Ended
	Dec. 31, 2019	Dec. 31, 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]
Estimate for expansion relating to construction cost		The planning for the Millbrook, NY expansion is underway and the Company is actively evaluating proposals for its construction. As of December 31, 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.
Millbrook, NY | Scenario, Forecast
Real Estate Properties [Line Items]
Gross square feet of traditional drive-up storage units and all-climate-controlled units	16,500