Self Administration Transaction - Additional Information (Detail)
 3 Months Ended 9 Months Ended
Jun. 28, 2019
USD ($)
Employee
$ / shares
shares
Sep. 30, 2020
USD ($)
Sep. 30, 2019
USD ($)
Sep. 30, 2020
USD ($)
Sep. 30, 2019
USD ($)
Dec. 31, 2019
USD ($)
Business Acquisition [Line Items]            
Legal fees and fees and expenses of professional and financial advisors       $ 1,600,000    
Estimated fair value of consideration transferred $ 111,300,000          
Gain resulting from acquisition of unconsolidated affiliates   $ 0 $ 0 0 $ 8,017,353  
Incremental assets under management   219,000,000   219,000,000    
Noncontrolling interests in our Operating Partnership   $ 61,270,970   $ 61,270,970   $ 71,988,256
Agreement term 3 years          
Strategic Storage Advisor II, LLC            
Business Acquisition [Line Items]            
Partnership units exchanged | shares 20,000          
Cash proceeds from partnership units exchanged $ 200,000          
Gain (loss) from partners capital account units exchanged 0          
Fair value of operating partnership units and special limited partnership interests contributed 18,800,000          
Noncontrolling interests in our Operating Partnership $ 9,100,000          
Fair Value, Inputs, Level 3            
Business Acquisition [Line Items]            
Alternative investment, measurement input 5.16%          
Minority and Marketability Discount | Fair Value, Inputs, Level 3            
Business Acquisition [Line Items]            
Alternative investment, measurement input 0.05          
Contribution Agreement            
Business Acquisition [Line Items]            
Percentage of fair value of equity interests 50.00%          
Gain resulting from acquisition of unconsolidated affiliates $ 8,000,000.0          
Contribution Agreement | SmartStop Asset Management            
Business Acquisition [Line Items]            
Percentage of voting membership interest 100.00%          
Number of on-site self storage employees | Employee 350          
Cash $ 769,126          
Debt assumption $ 15,000,000          
Contribution Agreement | Class A-1 Units | SmartStop Asset Management            
Business Acquisition [Line Items]            
Number of limited partnership units | shares 8,698,956          
Contribution Agreement | Class A-2 Units | SmartStop Asset Management            
Business Acquisition [Line Items]            
Number of limited partnership units | shares 3,283,302          
Operating Partnership Agreement            
Business Acquisition [Line Items]            
Number of limited partnership units | shares 20,000          
Cash received $ 200,000          
Operating Partnership Agreement | Class A-1 Units            
Business Acquisition [Line Items]            
Lock-up expiration date       Jun. 28, 2021    
Conversion of stock, description       The Class A-1 Units are subject to the general restrictions on transfer contained in the Operating Partnership Agreement. In addition, until June 28, 2021 (the “Lock-Up Expiration”), the Class A-1 Units may not be sold, pledged, or otherwise transferred or encumbered except in certain limited circumstances set forth in the Contribution Agreement.  The Class A-1 Units are otherwise entitled to all rights and duties of the Class A limited partnership units in the Operating Partnership, including cash distributions and the allocation of any profits or losses in the Operating Partnership.  The Class A-2 Units may convert into Class A-1 Units as earnout consideration, as described below.  The Class A-2 Units are not entitled to cash distributions or the allocation of any profits or losses in the Operating Partnership until the Class A-2 Units are converted into Class A-1 Units    
Operating Partnership Agreement | Class A-2 Units            
Business Acquisition [Line Items]            
Earnout unit exchange per share | $ / shares $ 10.66          
Class of unit expiration year 7 years          
Operating Partnership Agreement | Class A-2 Units | Unit Conversion Feature A            
Business Acquisition [Line Items]            
Class of unit conversion percentage 33.33%          
Operating Partnership Agreement | Class A-2 Units | Unit Conversion Feature A | Minimum            
Business Acquisition [Line Items]            
Incremental AUM under operating partnership $ 300,000,000          
Operating Partnership Agreement | Class A-2 Units | Unit Conversion Feature B            
Business Acquisition [Line Items]            
Class of unit conversion percentage 33.33%          
Operating Partnership Agreement | Class A-2 Units | Unit Conversion Feature B | Minimum            
Business Acquisition [Line Items]            
Incremental AUM under operating partnership $ 500,000,000          
Operating Partnership Agreement | Class A-2 Units | Unit Conversion Feature C            
Business Acquisition [Line Items]            
Class of unit conversion percentage 33.33%          
Operating Partnership Agreement | Class A-2 Units | Unit Conversion Feature C | Minimum            
Business Acquisition [Line Items]            
Incremental AUM under operating partnership $ 700,000,000          
Membership Interest Purchase Agreement | Terrace Rd LLC            
Business Acquisition [Line Items]            
Percentage of voting membership interest 100.00%          
Cash $ 2,300,000          
Debt assumption 4,200,000          
Purchase price $ 6,500,000