Consolidated Statements of Equity (Unaudited) - USD ($)
Total
SSGT Mergers
Self Administration Transaction
Redeemable Common Stock
Common Stock
Class A Common stock
Common Stock
Class T Common stock
Additional Paid-in Capital
Distributions
Accumulated Deficit
Accumulated Other Comprehensive Income (Loss)
Total SmartStop Self Storage REIT, Inc. Equity
Noncontrolling Interests
Noncontrolling Interests
SSGT Mergers
Noncontrolling Interests
Self Administration Transaction
Preferred Equity
Beginning Balance at Dec. 31, 2018 $ 345,256,897     $ 32,226,815 $ 50,437 $ 7,534 $ 500,474,807 $ (94,248,326) $ (62,340,153) $ 1,390,354 $ 345,334,653 $ (77,756)      
Beginning Balance (in shares) at Dec. 31, 2018         50,437,059 7,533,790                  
Offering costs (2,418)           (2,418)       (2,418)        
Issuance of limited partnership units in our Operating Partnership in connection with the SSGT Mergers/Self Administration Transaction   $ 4,217,399                     $ 4,217,399    
Changes to redeemable common stock (3,963,393)     3,963,393     (3,963,393)       (3,963,393)        
Redemptions of common stock (141)     (2,044,001) $ (120) $ (21)         (141)        
Redemptions of common stock (in shares)         (120,000) (21,291)                  
Distributions (8,411,426)             (8,411,426)     (8,411,426)        
Distributions to noncontrolling interests (46,584)                     (46,584)      
Issuance of shares for distribution reinvestment plan 3,963,766       $ 323 $ 50 3,963,393       3,963,766        
Issuance of shares for distribution reinvestment plan (in shares)         322,580 49,604                  
Equity based compensation expense 21,957           21,957       21,957        
Net loss attributable to SmartStop Self Storage REIT, Inc. stockholders (8,891,558)               (8,891,558)   (8,891,558)        
Net loss attributable to the noncontrolling interests in our Operating Partnership (56,759)                     (56,759)      
Foreign currency translation adjustment 867,261                 867,261 867,261        
Foreign currency hedge contract gain (loss) (846,581)                 (846,581) (846,581)        
Interest rate swap and cap contract gains (losses) (1,315,092)                 (1,315,092) (1,315,092)        
Ending Balance at Mar. 31, 2019 330,793,328     34,146,207 $ 50,640 $ 7,563 500,494,346 (102,659,752) (71,231,711) 95,942 326,757,028 4,036,300      
Ending Balance (in shares) at Mar. 31, 2019         50,639,639 7,562,103                  
Beginning Balance at Dec. 31, 2018 345,256,897     32,226,815 $ 50,437 $ 7,534 500,474,807 (94,248,326) (62,340,153) 1,390,354 345,334,653 (77,756)      
Beginning Balance (in shares) at Dec. 31, 2018         50,437,059 7,533,790                  
Net loss attributable to SmartStop Self Storage REIT, Inc. stockholders (19,318,829)                            
Net loss attributable to the noncontrolling interests in our Operating Partnership (1,455,039)                            
Interest rate swap and cap contract gains (losses) (4,000,275)                            
Ending Balance at Sep. 30, 2019 360,622,181     39,839,496 $ 51,149 $ 7,650 491,272,437 (119,904,285) (81,658,982) (3,172,074) 286,595,895 74,026,286      
Ending Balance (in shares) at Sep. 30, 2019         51,148,541 7,649,856                  
Beginning Balance at Dec. 31, 2018 345,256,897     32,226,815 $ 50,437 $ 7,534 500,474,807 (94,248,326) (62,340,153) 1,390,354 345,334,653 (77,756)      
Beginning Balance (in shares) at Dec. 31, 2018         50,437,059 7,533,790                  
Ending Balance at Dec. 31, 2019 345,813,823     43,391,362 $ 51,435 $ 7,700 491,433,240 (128,642,787) (87,090,486) (1,955,335) 273,803,767 72,010,056     $ 146,426,164
Ending Balance (in shares) at Dec. 31, 2019         51,435,124 7,699,893                  
Beginning Balance at Mar. 31, 2019 330,793,328     34,146,207 $ 50,640 $ 7,563 500,494,346 (102,659,752) (71,231,711) 95,942 326,757,028 4,036,300      
Beginning Balance (in shares) at Mar. 31, 2019         50,639,639 7,562,103                  
Offering costs (1,559)           (1,559)       (1,559)        
Issuance of limited partnership units in our Operating Partnership in connection with the SSGT Mergers/Self Administration Transaction     $ 63,643,000                     $ 63,643,000  
Issuance of limited partnership units in our Operating Partnership in exchange for special limited partnership interest 18,800,000           9,687,035       9,687,035 9,112,965      
Contribution of special limited partnership interest in exchange for limited partnership interests in our Operating Partnership (18,800,000)           (18,800,000)       (18,800,000)        
Noncontrolling interests related to the consolidated Tenant Programs joint ventures 21,800                     21,800      
Redemption of limited partnership interests held by our Former Advisor (200,000)           (291,103)       (291,103) 91,103      
Changes to redeemable common stock (4,049,066)     4,049,066     (4,049,066)       (4,049,066)        
Redemptions of common stock (211)     (2,052,078) $ (200) $ (11)         (211)        
Redemptions of common stock (in shares)         (199,883) (10,242)                  
Issuance of restricted stock 232       $ 232           232        
Issuance of restricted stock (in shares)         232,176                    
Distributions (8,533,201)             (8,533,201)     (8,533,201)        
Distributions to noncontrolling interests (105,140)                     (105,140)      
Issuance of shares for distribution reinvestment plan 4,049,444       $ 328 $ 50 4,049,066       4,049,444        
Issuance of shares for distribution reinvestment plan (in shares)         328,392 50,757                  
Equity based compensation expense 25,136           25,136       25,136        
Net loss attributable to SmartStop Self Storage REIT, Inc. stockholders (2,212,445)               (2,212,445)   (2,212,445)        
Net loss attributable to the noncontrolling interests in our Operating Partnership (71,527)                     (71,527)      
Foreign currency translation adjustment 1,192,459                 1,192,459 1,192,459        
Foreign currency hedge contract gain (loss) (1,039,585)                 (1,039,585) (1,039,585)        
Interest rate swap and cap contract gains (losses) (1,861,933)                 (1,861,933) (1,861,933)        
Ending Balance at Jun. 30, 2019 381,650,732     36,143,195 $ 51,000 $ 7,602 491,113,855 (111,192,953) (73,444,156) (1,613,117) 304,922,231 76,728,501      
Ending Balance (in shares) at Jun. 30, 2019         51,000,324 7,602,618                  
Offering costs (2,276)           (2,276)       (2,276)        
Changes to redeemable common stock (4,046,001)     4,046,001     (4,046,001)       (4,046,001)        
Redemptions of common stock (200)     (349,700) $ (197) $ (3)         (200)        
Redemptions of common stock (in shares)         (197,470) (3,546)                  
Issuance of restricted stock 17       $ 17           17        
Issuance of restricted stock (in shares)         16,886                    
Distributions (8,711,332)             (8,711,332)     (8,711,332)        
Distributions to noncontrolling interests (1,375,462)                     (1,375,462)      
Issuance of shares for distribution reinvestment plan 4,046,381       $ 329 $ 51 4,046,001       4,046,381        
Issuance of shares for distribution reinvestment plan (in shares)         328,801 50,784                  
Equity based compensation expense 160,858           160,858       160,858        
Net loss attributable to SmartStop Self Storage REIT, Inc. stockholders (8,214,826)               (8,214,826)   (8,214,826)        
Net loss attributable to the noncontrolling interests in our Operating Partnership (1,326,753)                     (1,326,753)      
Foreign currency translation adjustment (651,011)                 (651,011) (651,011)        
Foreign currency hedge contract gain (loss) (84,696)                 (84,696) (84,696)        
Interest rate swap and cap contract gains (losses) (823,250)                 (823,250) (823,250)        
Ending Balance at Sep. 30, 2019 360,622,181     39,839,496 $ 51,149 $ 7,650 491,272,437 (119,904,285) (81,658,982) (3,172,074) 286,595,895 74,026,286      
Ending Balance (in shares) at Sep. 30, 2019         51,148,541 7,649,856                  
Net loss attributable to SmartStop Self Storage REIT, Inc. stockholders (5,431,504)                            
Ending Balance at Dec. 31, 2019 345,813,823     43,391,362 $ 51,435 $ 7,700 491,433,240 (128,642,787) (87,090,486) (1,955,335) 273,803,767 72,010,056     146,426,164
Ending Balance (in shares) at Dec. 31, 2019         51,435,124 7,699,893                  
Offering costs (28,822)           (28,822)       (28,822)        
Preferred equity issuance costs                             (46,456)
Changes to redeemable common stock (3,979,539)     3,979,539     (3,979,539)       (3,979,539)        
Redemptions of common stock (42)       $ (42)           (42)        
Redemptions of common stock (in shares)         (42,040)                    
Issuance of restricted stock 48       $ 48           48        
Issuance of restricted stock (in shares)         47,842                    
Distributions (8,668,726)             (8,668,726)     (8,668,726)        
Distributions to noncontrolling interests (1,356,799)                     (1,356,799)      
Issuance of shares for distribution reinvestment plan 3,979,539       $ 322 $ 50 3,979,167       3,979,539        
Issuance of shares for distribution reinvestment plan (in shares)         322,411 50,046                  
Equity based compensation expense 219,603           219,603       219,603        
Net loss attributable to SmartStop Self Storage REIT, Inc. stockholders (35,073,951)               (35,073,951)   (35,073,951)        
Net loss attributable to the noncontrolling interests in our Operating Partnership (5,031,652)                     (5,031,652)      
Foreign currency translation adjustment (4,567,120)                 (3,959,904) (3,959,904) (607,216)      
Foreign currency hedge contract gain (loss) 4,566,795                 3,959,594 3,959,594 607,201      
Interest rate swap and cap contract gains (losses) (5,475,549)                 (4,747,520) (4,747,520) (728,029)      
Ending Balance at Mar. 31, 2020 290,397,608     47,370,901 $ 51,763 $ 7,750 491,623,649 (137,311,513) (122,164,437) (6,703,165) 225,504,047 64,893,561     146,379,708
Ending Balance (in shares) at Mar. 31, 2020         51,763,337 7,749,939                  
Beginning Balance at Dec. 31, 2019 345,813,823     43,391,362 $ 51,435 $ 7,700 491,433,240 (128,642,787) (87,090,486) (1,955,335) 273,803,767 72,010,056     146,426,164
Beginning Balance (in shares) at Dec. 31, 2019         51,435,124 7,699,893                  
Ending Balance at Jun. 30, 2020 271,955,685     51,374,754 $ 52,119 $ 7,801 491,870,566 (146,094,279) (130,655,858) (6,096,431) 209,083,918 62,871,767     146,379,708
Ending Balance (in shares) at Jun. 30, 2020         52,118,882 7,801,216                  
Beginning Balance at Dec. 31, 2019 345,813,823     43,391,362 $ 51,435 $ 7,700 491,433,240 (128,642,787) (87,090,486) (1,955,335) 273,803,767 72,010,056     146,426,164
Beginning Balance (in shares) at Dec. 31, 2019         51,435,124 7,699,893                  
Net loss attributable to SmartStop Self Storage REIT, Inc. stockholders (49,824,486)                            
Net loss attributable to the noncontrolling interests in our Operating Partnership (6,550,455)                            
Interest rate swap and cap contract gains (losses) (3,509,682)                            
Ending Balance at Sep. 30, 2020 256,678,555     54,116,173 $ 52,454 $ 7,853 492,156,465 (155,013,319) (136,914,972) (4,902,696) 195,385,785 61,292,770     146,379,708
Ending Balance (in shares) at Sep. 30, 2020         52,453,575 7,852,830                  
Beginning Balance at Mar. 31, 2020 290,397,608     47,370,901 $ 51,763 $ 7,750 491,623,649 (137,311,513) (122,164,437) (6,703,165) 225,504,047 64,893,561     146,379,708
Beginning Balance (in shares) at Mar. 31, 2020         51,763,337 7,749,939                  
Offering costs (22)           (22)       (22)        
Changes to redeemable common stock (4,011,353)     4,011,353     (4,011,353)       (4,011,353)        
Redemptions of common stock (1)     (7,500) $ (1)           (1)        
Redemptions of common stock (in shares)         (750)                    
Issuance of restricted stock 24       $ 24           24        
Issuance of restricted stock (in shares)         23,725                    
Distributions (8,782,766)             (8,782,766)     (8,782,766)        
Distributions to noncontrolling interests (1,356,800)                     (1,356,800)      
Issuance of shares for distribution reinvestment plan 4,011,353       $ 333 $ 51 4,010,969       4,011,353        
Issuance of shares for distribution reinvestment plan (in shares)         332,570 51,277                  
Equity based compensation expense 423,383           247,323       247,323 176,060      
Net loss attributable to SmartStop Self Storage REIT, Inc. stockholders (8,491,421)               (8,491,421)   (8,491,421)        
Net loss attributable to the noncontrolling interests in our Operating Partnership (933,443)                     (933,443)      
Foreign currency translation adjustment 1,959,220                 1,700,259 1,700,259 258,961      
Foreign currency hedge contract gain (loss) (1,932,451)                 (1,677,000) (1,677,000) (255,451)      
Interest rate swap and cap contract gains (losses) 672,354                 583,475 583,475 88,879      
Ending Balance at Jun. 30, 2020 271,955,685     51,374,754 $ 52,119 $ 7,801 491,870,566 (146,094,279) (130,655,858) (6,096,431) 209,083,918 62,871,767     146,379,708
Ending Balance (in shares) at Jun. 30, 2020         52,118,882 7,801,216                  
Offering costs (4,966)           (4,966)       (4,966)        
Changes to redeemable common stock (4,011,063)     4,011,063     (4,011,063)       (4,011,063)        
Redemptions of common stock       (1,269,644)                      
Distributions (8,919,040)             (8,919,040)     (8,919,040)        
Distributions to noncontrolling interests (1,406,034)                     (1,406,034)      
Issuance of shares for distribution reinvestment plan 4,011,063       $ 335 $ 52 4,010,676       4,011,063        
Issuance of shares for distribution reinvestment plan (in shares)         334,693 51,614                  
Equity based compensation expense 523,031           291,252       291,252 231,779      
Net loss attributable to SmartStop Self Storage REIT, Inc. stockholders (6,259,114)               (6,259,114)   (6,259,114)        
Net loss attributable to the noncontrolling interests in our Operating Partnership (585,360)                     (585,360)      
Foreign currency translation adjustment 1,069,449                 928,902 928,902 140,547      
Foreign currency hedge contract gain (loss) (988,609)                 (858,687) (858,687) (129,922)      
Interest rate swap and cap contract gains (losses) 1,293,513                 1,123,520 1,123,520 169,993      
Ending Balance at Sep. 30, 2020 $ 256,678,555     $ 54,116,173 $ 52,454 $ 7,853 $ 492,156,465 $ (155,013,319) $ (136,914,972) $ (4,902,696) $ 195,385,785 $ 61,292,770     $ 146,379,708
Ending Balance (in shares) at Sep. 30, 2020         52,453,575 7,852,830