Debt - Additional Information (Detail) $ in Millions																1 Months Ended	9 Months Ended
		Sep. 28, 2023 USD ($)	Jun. 15, 2023 USD ($)	May 19, 2023 CAD ($)	May 10, 2023 CAD ($)	May 04, 2023 CAD ($)	Apr. 13, 2023 USD ($)	Jan. 31, 2023 USD ($)	Dec. 20, 2022 USD ($)	Sep. 20, 2022 CAD ($)	May 26, 2022 USD ($)	May 17, 2022 USD ($)	Apr. 26, 2022 USD ($)	Dec. 30, 2021 USD ($)	Nov. 30, 2021 USD ($) SpecialEntity	May 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 15, 2023 CAD ($)	Jan. 31, 2023 CAD ($)	Dec. 20, 2022 CAD ($)	Dec. 19, 2022 USD ($)	Sep. 21, 2022 USD ($)	Jul. 08, 2022 USD ($)	Jul. 08, 2021 USD ($)
Line Of Credit Facility [Line Items]
Weighted average interest rate																	7.89%
Payments of interest on loan																	$ 50,000,000	$ 30,608,851
CDOR
Line Of Credit Facility [Line Items]
Notional amount	[1]																$ 25,000,000
SmartStop Delayed Draw Mezzanine Loan Agreement
Line Of Credit Facility [Line Items]
Repaid outstanding balance																$ 50,000,000
SmartStop Delayed Draw Mezzanine Loan Agreement | St. John Property
Line Of Credit Facility [Line Items]
Additional borrowings from credit facility																								$ 7,200,000
SmartStop Delayed Draw Mezzanine Loan Agreement | Oxford Property
Line Of Credit Facility [Line Items]
Additional borrowings from credit facility																							$ 11,000,000
Huntington Credit Facility
Line Of Credit Facility [Line Items]
Number of Special Purpose Entities | SpecialEntity															3
Line of credit facility, maximum borrowing capacity							$ 107,600,000								$ 50,000,000
Term loan maturity date		Nov. 30, 2025					Nov. 30, 2025										Nov. 30, 2025
Applicable interest rate	[2]																7.93%
Line of credit facility, amount borrowed							$ 12,500,000						$ 12,900,000	$ 14,700,000	$ 22,400,000
Debt Instrument, Interest Rate, Effective Percentage																	7.93%
Huntington Credit Facility | Floor
Line Of Credit Facility [Line Items]
Applicable interest rate		3.25%
Huntington Credit Facility | Secured Overnight Financing Rate
Line Of Credit Facility [Line Items]
Debt instrument variable interest rate		2.61%
Interest rate term																	1 month Term
Huntington Credit Facility | Second Amendment
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity												$ 100,000,000
Line of credit facility, amount borrowed											$ 30,600,000	14,500,000
Line of credit, additional borrowing capacity												$ 50,000,000
Huntington Credit Facility | Interest Rate Swap Agreement
Line Of Credit Facility [Line Items]
Notional amount							$ 60,000,000
Huntington Credit Facility | Interest Rate Swap Agreement | Secured Overnight Financing Rate
Line Of Credit Facility [Line Items]
Applicable interest rate							4.01%
Huntington Credit Facility | Interest Rate Cap
Line Of Credit Facility [Line Items]
Notional amount		$ 47,600,000					$ 47,600,000
Huntington Credit Facility | Interest Rate Cap | Secured Overnight Financing Rate
Line Of Credit Facility [Line Items]
Applicable interest rate		1.10%					2.60%
Huntington Bridge Loan
Line Of Credit Facility [Line Items]
Debt instrument carrying amount													$ 30,600,000
Debt instrument maturity date													Jul. 25, 2022
Huntington Bridge Loan | Floor
Line Of Credit Facility [Line Items]
Applicable interest rate													3.25%
Huntington Bridge Loan | Secured Overnight Financing Rate
Line Of Credit Facility [Line Items]
Debt instrument variable interest rate													2.61%
Skymar Loan
Line Of Credit Facility [Line Items]
Term loan maturity date																	Aug. 01, 2024								Aug. 01, 2024
Applicable interest rate																	4.125%								4.125%
Mortgage loan, amount																									$ 4,800,000
Loans from SmartStop OP, L.P. | SmartStop Delayed Draw Mezzanine Loan Agreement | Bradenton Property and Apopka Property
Line Of Credit Facility [Line Items]
Commitment fee percentage														1.00%
Line of credit facility, amount borrowed														$ 6,800,000
Loans from SmartStop OP, L.P. | SmartStop Delayed Draw Mezzanine Loan Agreement | Cambridge Property
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity									$ 55,000,000													$ 45,000,000
Line of credit facility, amount borrowed									$ 10,000,000
Loans from SmartStop OP, L.P. | SmartStop Delayed Draw Mezzanine Loan Agreement | Edmonton Property
Line Of Credit Facility [Line Items]
Additional borrowings from credit facility								$ 15,000,000
Loans from SmartStop OP, L.P. | SmartStop Delayed Draw Mezzanine Loan Agreement | Secured Overnight Financing Rate | Cambridge Property
Line Of Credit Facility [Line Items]
Debt instrument, description of variable rate basis									SOFR plus 3%
Loans from SmartStop OP, L.P. | SmartStop Bridge Loan Agreement | Ontario Portfolio
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			$ 15,000,000
Commitment fee percentage			1.00%
Applicable interest rate																	8.31%
Extension fee payment			$ 37,500
Increase to interest rate			1.00%
Debt instrument maturity date			Dec. 31, 2023
Loans from SmartStop OP, L.P. | SmartStop Bridge Loan Agreement | Secured Overnight Financing Rate | Ontario Portfolio
Line Of Credit Facility [Line Items]
Debt instrument, description of variable rate basis			SOFR plus 3.00%
Debt instrument variable interest rate			3.00%
Loans from SmartStop OP, L.P. | Maximum | SmartStop Delayed Draw Mezzanine Loan Agreement | Bradenton Property and Apopka Property
Line Of Credit Facility [Line Items]
Loan in connection with acquisition of Bradenton Property and Apopka Property														$ 45,000,000
National Bank of Canada Loan | Acquisition of North York Property
Line Of Credit Facility [Line Items]
Debt instrument carrying amount																				$ 25.0
National Bank of Canada Loan | CDOR | Acquisition of North York Property
Line Of Credit Facility [Line Items]
Debt instrument variable interest rate								2.40%
Interest rate term								one month
National Bank of Canada Loan | Interest Rate Swap Agreement | Acquisition of North York Property
Line Of Credit Facility [Line Items]
Notional amount																				$ 25.0
Debt instrument maturity date								Jan. 31, 2025
Debt instrument, frequency of payment								monthly
Debt instrument amortization period								25 years
National Bank of Canada Loan | Interest Rate Swap Agreement | CDOR | Acquisition of North York Property
Line Of Credit Facility [Line Items]
Applicable interest rate								3.79%												3.79%
National Bank of Canada | Cambridge Property
Line Of Credit Facility [Line Items]
Repaid outstanding balance					$ 0.4
Term loan																					$ 15.5
National Bank of Canada | Burlington Property
Line Of Credit Facility [Line Items]
Term loan										$ 16.5
National Bank of Canada | CDOR | Cambridge Property
Line Of Credit Facility [Line Items]
Debt instrument variable interest rate									2.25%
Interest rate term									one month
National Bank of Canada | CDOR | Burlington Property
Line Of Credit Facility [Line Items]
Debt instrument variable interest rate										2.25%
Interest rate term										one month
National Bank of Canada | Interest Rate Swap Agreement | Cambridge Property
Line Of Credit Facility [Line Items]
Notional amount																					$ 15.5
Debt instrument maturity date									Dec. 20, 2025
Debt instrument, frequency of payment									monthly
Debt instrument amortization period									25 years
National Bank of Canada | Interest Rate Swap Agreement | Burlington Property
Line Of Credit Facility [Line Items]
Notional amount										$ 16.5
Debt instrument maturity date										Sep. 20, 2025
Debt instrument, frequency of payment										monthly
Debt instrument amortization period										25 years
National Bank of Canada | Interest Rate Swap Agreement | CDOR | Cambridge Property
Line Of Credit Facility [Line Items]
Applicable interest rate									3.83%												3.83%
National Bank of Canada | Interest Rate Swap Agreement | CDOR | Burlington Property
Line Of Credit Facility [Line Items]
Applicable interest rate										4.02%
Bank of Montreal Loan
Line Of Credit Facility [Line Items]
Debt instrument carrying amount						$ 21.6
Debt instrument maturity date						May 04, 2025
Debt instrument, initial term						2 years
Extension option period						1 year
Bank of Montreal Loan | CDOR
Line Of Credit Facility [Line Items]
Debt instrument variable interest rate						2.50%
Interest rate term						one-month
Bank of Montreal Loan | Interest Rate Swap Agreement
Line Of Credit Facility [Line Items]
Notional amount						$ 21.6
Bank of Montreal Loan | Interest Rate Swap Agreement | CDOR
Line Of Credit Facility [Line Items]
Applicable interest rate						4.47%
First National Loan
Line Of Credit Facility [Line Items]
Term loan maturity date																	May 18, 2025
Applicable interest rate	[3]																9.10%
Debt instrument carrying amount				$ 8.8
Debt instrument maturity date				May 18, 2025
Debt instrument, initial term				2 years
First National Loan | Royal Bank of Canada Prime Rate
Line Of Credit Facility [Line Items]
Debt instrument variable interest rate				1.90%
National Bank of Canada - Ontario Loan
Line Of Credit Facility [Line Items]
Debt instrument carrying amount																			$ 127.2
Debt instrument maturity date			Jun. 15, 2025
Debt instrument, frequency of payment			monthly
Debt instrument amortization period			25 years
National Bank of Canada - Ontario Loan | CDOR
Line Of Credit Facility [Line Items]
Debt instrument variable interest rate			2.60%
Interest rate term			one month
National Bank of Canada - Ontario Loan | Minimum
Line Of Credit Facility [Line Items]
Debt service coverage ratio			0.01
National Bank of Canada - Ontario Loan | Maximum
Line Of Credit Facility [Line Items]
Debt service coverage ratio			0.013
National Bank of Canada - Ontario Loan | Interest Rate Swap Agreement
Line Of Credit Facility [Line Items]
Notional amount																			$ 127.2
National Bank of Canada - Ontario Loan | Interest Rate Swap Agreement | CDOR
Line Of Credit Facility [Line Items]
Applicable interest rate			4.73%																4.73%
Extended Maturity | Huntington Credit Facility
Line Of Credit Facility [Line Items]
Term loan maturity date		Nov. 30, 2027
Extended Maturity | Loans from SmartStop OP, L.P. | SmartStop Delayed Draw Mezzanine Loan Agreement | Cambridge Property
Line Of Credit Facility [Line Items]
Debt instrument maturity date									Dec. 30, 2023
Extended Maturity | Loans from SmartStop OP, L.P. | SmartStop Bridge Loan Agreement | Ontario Portfolio
Line Of Credit Facility [Line Items]
Debt instrument maturity date			Dec. 31, 2024

[1] Notional amount is denominated in CAD and has been designated as a cash flow hedge.

[2] This variable rate loan encumbers 12 properties (Phoenix I, Phoenix II, Surprise, Bradenton, Apopka, Vancouver WA, Portland, Newark, Levittown, Chandler, St. Johns and Oxford). We entered into interest rate swap agreements and an interest rate cap that fixes SOFR at 2.72% until the maturity of the loan.

[3] This variable rate loan encumbers our Edmonton, AB property and the amount shown above is in USD based on the foreign exchange rate in effect as of September 30, 2023.