Investment in Joint Ventures - Summary of Company's Unconsolidated Joint Ventures (Parenthetical) (Detail) $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) Property	Sep. 30, 2020 USD ($) Property	Mar. 31, 2021 USD ($) Property	Mar. 31, 2020 USD ($) Property	Dec. 31, 2020 USD ($)
Schedule of Equity Method Investments [Line Items]
Number of storage facilities acquired | Property			16	6
Cash payment for property acquisition			$ 265,197	$ 124,204
Mortgages payable	$ 37,596		$ 37,596		$ 37,777
Ontario, Canada [Member]
Schedule of Equity Method Investments [Line Items]
Number of joint venture developing self-storage facilities | Property	2		2
NY [Member]
Schedule of Equity Method Investments [Line Items]
Number of joint venture developing self-storage facilities | Property	4		4
Tucson, AZ [Member]
Schedule of Equity Method Investments [Line Items]
Number of joint venture developing self-storage facilities | Property	1		1
Sovran HHF Storage Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Excess of investment over net asset due to capitalization of acquisition related costs	$ 1,700		$ 1,700
Total consideration acquired		$ 175,200
Settlement of principal balances with non-recourse loans		34,000
Gain on sale of storage facilities		$ 2,100
Sovran HHF Storage Holdings LLC [Member] | Storage Facilities [Member]
Schedule of Equity Method Investments [Line Items]
Number of storage facilities acquired | Property		17
Sovran HHF Storage Holdings LLC [Member] | Storage Facilities [Member] | Third Party [Member]
Schedule of Equity Method Investments [Line Items]
Total consideration acquired		$ 42,300
Number of properties sold | Property		4
Sovran HHF Storage Holdings II LLC [Member]
Schedule of Equity Method Investments [Line Items]
Total consideration acquired		$ 120,200
Cash has been placed into escrow until non-recourse loans		35,800
Contribution of company to joint venture as share in capital		$ 12,700
Sovran HHF Storage Holdings II LLC [Member] | Storage Facilities [Member]
Schedule of Equity Method Investments [Line Items]
Number of storage facilities acquired | Property		8
Iskalo Office Holdings, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Rent paid during the period			$ 400	300
Life Storage Virtus, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Contribution of company to joint venture as share in capital					$ 1,700
Life Storage Virtus, LLC [Member] | Storage Facilities [Member]
Schedule of Equity Method Investments [Line Items]
Cash payment for property acquisition				21,700
Mortgages payable				$ 14,000
SNL Orix Merrick, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Total consideration acquired	$ 47,900
Joint Ventures with Properties in Development Stage [Member]
Schedule of Equity Method Investments [Line Items]
Number Of joint ventures | Property			7
Joint Ventures with Properties in Development Stage [Member] | Common Stock Shares [Member]
Schedule of Equity Method Investments [Line Items]
Contribution of company to joint venture as share in capital			$ 11,500