Commitment and Contingencies - Additional Information (Detail) $ in Thousands		1 Months Ended		3 Months Ended		9 Months Ended
	Oct. 01, 2022 USD ($) Property	Oct. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) Property	Sep. 30, 2021 USD ($) Property	Dec. 31, 2021 USD ($)
Commitment And Contingencies [Line Items]
Operating lease, aggregate right-of-use assets			$ 17,700	$ 17,700		$ 17,700		$ 19,500
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]			Other assets	Other assets		Other assets		Other assets
Operating lease liabilities			$ 17,200	$ 17,200		$ 17,200		$ 19,200
Operating Lease, Liability, Statement of Financial Position [Extensible List]			us-gaap:AccountsPayableAndAccruedLiabilitiesMember	us-gaap:AccountsPayableAndAccruedLiabilitiesMember		us-gaap:AccountsPayableAndAccruedLiabilitiesMember		us-gaap:AccountsPayableAndAccruedLiabilitiesMember
Operating lease expenses				$ 700	$ 600	$ 2,000	$ 1,800
Weighted average remaining lease term			9 years 7 months 6 days	9 years 7 months 6 days		9 years 7 months 6 days
Weighted average discount rate			4.59%	4.59%		4.59%
Operating lease commitments			$ 22,347	$ 22,347		$ 22,347
Purchase price of business to be acquired			$ 59,000
Number of storage facilities acquired | Property						43	62
Purchase Price						$ 860,638
Expansion and enhancement contracts						48,200
Self-storage Facilities [Member]
Commitment And Contingencies [Line Items]
Purchase price of business to be acquired	$ 142,000					$ 280,300
Number of storage facilities acquired | Property	7					15
Self-storage Facilities [Member] | Corporate Joint Venture [Member]
Commitment And Contingencies [Line Items]
Purchase price of business to be acquired	$ 59,000					$ 81,500
Number of storage facilities acquired | Property	3					4
Business combination share value owned	$ 11,800
Self-storage Facilities [Member] | Facility Acquired [Member]
Commitment And Contingencies [Line Items]
Purchase Price		$ 67,500