Investments in Unconsolidated Real Estate Entities - Additional Information (Details) $ in Thousands		1 Months Ended	12 Months Ended
	Apr. 30, 2018 USD ($) store	Jan. 31, 2019 USD ($) store	Dec. 31, 2020 USD ($) store	Dec. 31, 2019 USD ($) store	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Contributions joint ventures			$ 14,792
Number of operating stores acquired | store			1
Number of stores acquired at certificate of occupancy | store			5
Number of stores acquired | store			23	21
Cash paid to acquire properties			$ 254,111	$ 279,313
Loans assumed			0	17,157	$ 87,500
Amortization amount of excess purchase price included in equity earnings			$ 25,251
Amortization period of excess purchase price included in equity earnings			40 years
Management fee revenues			$ 15,657	$ 14,624	$ 12,650
East Space West One LLC and East Space West Two LLC
Schedule of Equity Method Investments [Line Items]
Number of stores acquired | store		12
Cash paid to acquire properties		$ 172,505
Ownership interest held by entity (as a percent)		100.00%
WCOT Self Storage LLC
Schedule of Equity Method Investments [Line Items]
Number of stores acquired | store	14
Cash paid to acquire properties	$ 115,797
Loans assumed	$ 87,500