Investment in Storage Facilities and Intangible Assets - Additional Information (Detail)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($) $ / shares	Mar. 31, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) Property $ / shares	Jun. 30, 2018 USD ($) $ / shares	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)
Investment Holdings [Line Items]
Number of storage facilities acquired | Property				6
Payments to acquire businesses and interest in affiliates				$ 10,715,000
Consideration paid, Cash Paid				98,526,000
Deposits paid at the time of contract						$ 200,000
Net other liabilities assumed				$ 441,000
Amortization period for in-place customer leases on a straight-line basis				12 months
Amortization expense related to in-place customer leases	$ 500,000		$ 0	$ 900,000	$ 0
Increase in depreciation expense due to facility replacement	$ 100,000			$ 800,000	$ 300,000
Accelerated depreciation reduced basic and diluted earnings per share | $ / shares				$ 0.02	$ 0.01
Maximum [Member]
Investment Holdings [Line Items]
Accelerated depreciation reduced basic and diluted earnings per share | $ / shares	$ 0.01
Scenario, Forecast [Member]
Investment Holdings [Line Items]
Cash payable in future							$ 1,200,000
Review Avenue Partners, LLC [Member]
Investment Holdings [Line Items]
Equity method investment ownership percentage acquired		60.00%		60.00%
Payments to acquire businesses and interest in affiliates		$ 10,700,000		$ 10,700,000