Debt - Additional Information (Detail)
3 Months Ended 9 Months Ended
Aug. 03, 2020
USD ($)
Jun. 07, 2019
USD ($)
Jan. 24, 2019
USD ($)
Property
Extension
Oct. 11, 2018
CAD ($)
Property
Extension
SpecialPurposeEntity
Sep. 30, 2020
USD ($)
Sep. 30, 2019
USD ($)
Sep. 30, 2020
USD ($)
Sep. 30, 2019
USD ($)
Sep. 30, 2020
CAD ($)
May 08, 2020
USD ($)
Dec. 31, 2019
USD ($)
Oct. 29, 2019
USD ($)
Jul. 08, 2019
CAD ($)
Jan. 29, 2019
USD ($)
Jan. 25, 2019
CAD ($)
Oct. 01, 2018
USD ($)
Debt Instrument [Line Items]                                
Weighted average interest rate on debt         3.73%   3.73%   3.73%              
Loss on extinguishment of debt         $ 0 $ 0 $ 0 $ (1,487,867)                
Debt Instrument Carrying Amount         717,069,469   $ 717,069,469                  
Line of credit facility, number of extension options | Extension     2                          
Line of credit facility, term of extension options     1 year                          
Derivative, notional amount                         $ 95,000,000 $ 161,200,000 $ 90,000,000  
Debt instrument face amount     $ 500,178,000                          
Minimum | Secured Loan Amendment                                
Debt Instrument [Line Items]                                
Amendment to secured loan with secured lenders                   $ 10,000,000            
Maximum | Secured Loan Amendment                                
Debt Instrument [Line Items]                                
Amendment to secured loan with secured lenders                   $ 15,000,000            
Fixed Rate Secured Debt                                
Debt Instrument [Line Items]                                
Debt instrument, description of variable rate basis             LIBOR plus 2.5%                  
Debt instrument, basis spread on variable rate     2.50%                          
Derivative, notional amount     $ 89,200,000                          
Debt instrument, interest rate     2.60%                          
Debt instrument face amount     $ 89,178,000                          
Fixed Rate Secured Debt                                
Debt Instrument [Line Items]                                
Number of wholly owned properties | Property     16                          
Debt Instrument Maturity Date             Jan. 24, 2022                  
Line of credit facility, number of extension options | Extension     1                          
Line of credit facility, term of extension options     1 year                          
Debt instrument face amount     $ 89,200,000                          
LIBOR | Minimum | Secured Loan Amendment                                
Debt Instrument [Line Items]                                
Debt Instrument, Interest Rate                   0.50%            
Interest Rate Cap                                
Debt Instrument [Line Items]                                
Debt Instrument Maturity Date Aug. 02, 2021                              
Derivative, notional amount $ 80,000,000                              
Debt instrument, interest rate 0.50%                              
Interest Rate Cap | LIBOR                                
Debt Instrument [Line Items]                                
Debt instrument, interest rate 0.50%                              
Interest Rate Swap | Fixed Rate Secured Debt | Termination                                
Debt Instrument [Line Items]                                
Derivative, notional amount                       $ 85,500,000        
KeyBank and Citi Real Estate Funding                                
Debt Instrument [Line Items]                                
Debt Instrument Carrying Amount     235,000,000                          
CMBS SASB Mortgage Loan                                
Debt Instrument [Line Items]                                
Debt Instrument Carrying Amount     $ 180,000,000                          
Number of wholly owned properties | Property     29                          
Debt Instrument Maturity Date             Feb. 09, 2022                  
Derivative, notional amount     $ 180,000,000                          
Derivative, inception date             Jan. 24, 2019                  
CMBS SASB Mortgage Loan | Interest Rate Cap                                
Debt Instrument [Line Items]                                
Derivative, notional amount   $ 180,000,000                            
CMBS SASB Mezzanine Loan                                
Debt Instrument [Line Items]                                
Debt Instrument Carrying Amount     $ 55,000,000                          
Number of special purpose entities | Property     29                          
Debt Instrument Maturity Date             Feb. 09, 2022                  
Derivative, notional amount     $ 55,000,000                          
Derivative, inception date             Jan. 24, 2019                  
CMBS SASB Mezzanine Loan | Interest Rate Cap                                
Debt Instrument [Line Items]                                
Derivative, notional amount   $ 55,000,000                            
CMBS SASB Loan                                
Debt Instrument [Line Items]                                
Debt instrument, description             (a) the borrower with respect to the CMBS SASB Mortgage Loan has purchased an interest rate cap with a notional amount of $180 million, with an effective date of January 24, 2019, whereby LIBOR is capped at 3% through February 15, 2022 and (b) the borrower with respect to the CMBS SASB Mezzanine Loan has purchased an interest rate cap with a notional amount of $55 million, with an effective date of January 24, 2019, whereby LIBOR is capped at 3% through February 15, 2022. On June 7, 2019, to effectively terminate our $180 million and $55 million existing interest rate caps, we sold an offsetting interest rate cap with a notional amount of $235 million, whereby LIBOR is capped at 3% through February 15, 2022.  We simultaneously entered into an interest rate swap with a notional amount of $235 million, whereby LIBOR is fixed at 1.79% through February 15, 2022. None of the CMBS SASB Loan may be prepaid, in whole or in part, without satisfying certain conditions as set forth in the respective CMBS SASB Loan Agreements, such as the payment of a spread maintenance premium if the prepayment is made within the first two years. Thereafter the CMBS SASB Loan may be prepaid in whole or in part at par without penalty                  
Debt instrument face amount     $ 235,000,000                          
CMBS SASB Loan | LIBOR                                
Debt Instrument [Line Items]                                
Debt instrument, description of variable rate basis     LIBOR plus 3%                          
Debt instrument, basis spread on variable rate     3.00%                          
CMBS SASB Loan | Interest Rate Cap                                
Debt Instrument [Line Items]                                
Debt Instrument Maturity Date   Feb. 15, 2022                            
Derivative, notional amount   $ 235,000,000                            
Debt instrument, interest rate   3.00%                            
CMBS SASB Loan | Interest Rate Swap                                
Debt Instrument [Line Items]                                
Debt Instrument Maturity Date   Feb. 15, 2022                            
Derivative, notional amount   $ 235,000,000                            
Debt instrument, interest rate   1.79%                            
KeyBank CMBS Loan                                
Debt Instrument [Line Items]                                
Debt Instrument Carrying Amount     $ 104,000,000                          
Number of wholly owned properties | Property     10                          
Debt Instrument Maturity Date     Feb. 01, 2029                          
Debt instrument, interest rate     5.00%                          
Minimum Number of Years to Defease the Loan     2 years                          
Secured Loan                                
Debt Instrument [Line Items]                                
Debt Instrument Carrying Amount [1],[2]         $ 85,512,000   $ 85,512,000       $ 85,512,000          
Debt Instrument Maturity Date [1],[2]             Jan. 24, 2022                  
Debt Instrument, Interest Rate [1],[2]         3.00%   3.00%   3.00%              
Number of properties encumbered         16   16                  
Secured Loan | Fixed Rate Secured Debt                                
Debt Instrument [Line Items]                                
Outstanding balance on credit facility         $ 85,500,000   $ 85,500,000       $ 85,500,000          
Secured Loan | Interest Rate Cap | LIBOR                                
Debt Instrument [Line Items]                                
Debt instrument, interest rate                           2.60%    
Secured Loan | Interest Rate Swap                                
Debt Instrument [Line Items]                                
Derivative, notional amount                       $ 85,500,000        
Canadian CitiBank | Canadian Debt Refinancing                                
Debt Instrument [Line Items]                                
Number of special purpose entities | SpecialPurposeEntity       10                        
Line of credit facility, number of extension options | Extension       3                        
Line of credit facility, term of extension options       1 year     1 year                  
Derivative, notional amount       $ 112,000,000         $ 111,300,000              
Debt instrument, interest rate       3.00%                        
Debt instrument, interest rate       0.25%                        
Number of properties encumbered | Property       10                        
Maximum borrowings under credit facility       $ 112,000,000                        
Proceeds from line of credit       $ 99,300,000                        
Line of credit facility, description             The CitiBank Loan Agreement is a term loan, the original maturity date was October 9, 2020. The loan may, in certain circumstances, be extended at our option for three consecutive terms of one year each. We exercised the first one year extension option, extending the maturity date to October 9, 2021.  Monthly payments due under the CitiBank Loan Agreement are interest-only, with the full principal amount becoming due and payable on the maturity date.                  
Line of credit facility, maturity date       Oct. 09, 2020                        
Line of credit facility extended expiration date             Oct. 09, 2021                  
Line of credit, interest rate description             The amounts outstanding under the CitiBank Loan Agreement bear interest at a rate equal to the sum of the “CDOR” (as defined in the CitiBank Loan Agreement) and 2.25%.                  
Canadian CitiBank | Maximum | Canadian Debt Refinancing                                
Debt Instrument [Line Items]                                
Line of credit facility, Additional borrowing capacity                 $ 700,000              
Strategic Storage Growth Trust, Inc                                
Debt Instrument [Line Items]                                
Loss on extinguishment of debt     $ 1,500,000                          
Debt Instrument Carrying Amount                               $ 19,000,000
Debt instrument face amount     $ 500,000,000                          
[1] On January 29, 2019, we entered into a $161.2 million notional interest rate swap whereby LIBOR was fixed at approximately 2.6% until August 1, 2020. On October 29, 2019, in connection with the pay off of the Senior Term Loan, we terminated approximately $75.7 million of this interest rate swap which required a settlement payment of approximately $0.6 million. The remaining $85.5 million of the interest rate swap effectively fixed the interest rate on the Secured Loan at 5.1% until August 1, 2020. To continue hedging our interest rate risk related to this loan, we purchased an interest rate cap on August 3, 2020 with a notional amount of $80 million that effectively caps LIBOR at 0.5% through August 2, 2021.
[2] This variable rate loan encumbers 16 properties (Colorado Springs, Aurora, Phoenix, 3173 Sweeten Creek Rd - Asheville, Elk Grove, Garden Grove, Deaverview Rd - Asheville, Highland Center Blvd - Asheville, Sarasota, Mount Pleasant, Pembroke Pines, Riverview, Eastlake, McKinney, Hualapai Way - Las Vegas, Gilbert). The separate assets of these encumbered properties are not available to pay our other debts.