Commitments and Contingencies - Additional Information (Detail) $ in Millions		1 Months Ended	12 Months Ended
	Feb. 19, 2021 Property	Jan. 31, 2021 USD ($) Property	Dec. 31, 2020 USD ($) Property	Dec. 31, 2019 Property
Commitment And Contingencies [Line Items]
Operating lease commitments			$ 26.1
Number of storage facilities acquired | Property			40	30
Expansion and enhancement contracts			$ 24.0
Self-storage Facilities [Member]
Commitment And Contingencies [Line Items]
Purchase price of business to be acquired			$ 111.3
Number of storage facilities acquired | Property			10
Self-storage Facilities [Member] | Subsequent Event [Member]
Commitment And Contingencies [Line Items]
Purchase price of business to be acquired		$ 26.3
Number of storage facilities acquired | Property	1	2