Commitment and Contingencies - Additional Information (Detail) $ in Thousands			3 Months Ended
	May 05, 2021 USD ($) Property	May 03, 2021 USD ($) Property	Mar. 31, 2021 USD ($) Property	Mar. 31, 2020 USD ($) Property	Dec. 31, 2020 USD ($)
Commitment And Contingencies [Line Items]
Operating lease, aggregate right-of-use assets			$ 19,900		$ 20,300
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]			us-gaap:OtherAssetsMember		us-gaap:OtherAssetsMember
Operating lease liabilities			$ 19,700		$ 19,900
Operating Lease, Liability, Statement of Financial Position [Extensible List]			us-gaap:AccountsPayableAndAccruedLiabilitiesMember		us-gaap:AccountsPayableAndAccruedLiabilitiesMember
Operating lease expenses			$ 600	$ 500
Weighted average remaining lease term			11 years 2 months 12 days
Weighted average discount rate			4.67%
Operating lease commitments			$ 25,672
Number of storage facilities acquired | Property			16	6
Purchase Price			$ 266,215
Expansion and enhancement contracts			33,800
Self-storage Facilities [Member]
Commitment And Contingencies [Line Items]
Purchase price of business to be acquired			$ 106,500
Number of storage facilities acquired | Property			6
Self-storage Facilities [Member] | Subsequent Event [Member]
Commitment And Contingencies [Line Items]
Number of storage facilities acquired | Property	11	1
Purchase Price	$ 159,200	$ 16,500