v3.26.3
Shareholder Report, Line Graph (Details) - USD ($)
 5 Months Ended 11 Months Ended 12 Months Ended 17 Months Ended 23 Months Ended
Sep. 27, 2024
Feb. 28, 2025
Aug. 31, 2025
Aug. 31, 2026
Feb. 28, 2026
Aug. 31, 2026
American Funds® U.S. Small and Mid Cap Equity Fund - Class A            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class A (with sales charge)    
Accumulated Value $ 9,425 $ 9,496 $ 10,506   $ 11,479 $ 11,962
American Funds® U.S. Small and Mid Cap Equity Fund - Class C            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class C (with sales charge)    
Accumulated Value 10,000 10,075 11,147   12,179 12,691
American Funds® U.S. Small and Mid Cap Equity Fund - Class F-1            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class F-1    
Accumulated Value 10,000 10,075 11,147   12,182 12,694
American Funds® U.S. Small and Mid Cap Equity Fund - Class F-2            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class F-2    
Accumulated Value 10,000 10,075 11,147   12,180 12,691
American Funds® U.S. Small and Mid Cap Equity Fund - Class F-3            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class F-3    
Accumulated Value 10,000 10,082 11,175   12,229 12,752
American Funds® U.S. Small and Mid Cap Equity Fund - Class 529-A            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class 529-A (with sales charge)    
Accumulated Value 9,650 9,721 10,755   11,745 12,229
American Funds® U.S. Small and Mid Cap Equity Fund - Class 529-C            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class 529-C (with sales charge)    
Accumulated Value 10,000 10,074 11,145   12,171 12,672
American Funds® U.S. Small and Mid Cap Equity Fund - Class 529-E            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class 529-E    
Accumulated Value 10,000 10,074 11,145   12,171 12,672
American Funds® U.S. Small and Mid Cap Equity Fund - Class 529-F-2            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class 529-F-2    
Accumulated Value 10,000 10,074 11,145   12,168 12,670
American Funds® U.S. Small and Mid Cap Equity Fund - Class 529-F-3            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class 529-F-3    
Accumulated Value 10,000 10,081 11,173   12,221 12,734
American Funds® U.S. Small and Mid Cap Equity Fund - Class R-1            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class R-1    
Accumulated Value 10,000 10,082 11,174   12,227 12,750
American Funds® U.S. Small and Mid Cap Equity Fund - Class R-2            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class R-2    
Accumulated Value 10,000 10,075 11,167   12,221 12,744
American Funds® U.S. Small and Mid Cap Equity Fund - Class R-2E            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class R-2E    
Accumulated Value 10,000 10,079 11,171   12,226 12,749
American Funds® U.S. Small and Mid Cap Equity Fund - Class R-3            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class R-3    
Accumulated Value 10,000 10,081 11,173   12,227 12,751
American Funds® U.S. Small and Mid Cap Equity Fund - Class R-4            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class R-4    
Accumulated Value 10,000 10,081 11,174   12,227 12,751
American Funds® U.S. Small and Mid Cap Equity Fund - Class R-5E            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class R-5E    
Accumulated Value 10,000 10,081 11,173   12,227 12,751
American Funds® U.S. Small and Mid Cap Equity Fund - Class R-5            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class R-5    
Accumulated Value 10,000 10,082 11,174   12,227 12,751
American Funds® U.S. Small and Mid Cap Equity Fund - Class R-6            
Account Value [Line Items]            
Line Graph and Table Measure Name       American Funds U.S. Small and Mid Cap Equity Fund — Class R-6    
Accumulated Value 10,000 10,083 11,175   12,232 12,755
Russell 3000 Index [Member]            
Account Value [Line Items]            
Line Graph and Table Measure Name       Russell 3000 Index    
Accumulated Value 10,000 10,425 11,393   12,199 13,684
Russell Midcap Index [Member]            
Account Value [Line Items]            
Line Graph and Table Measure Name       Russell Midcap Index    
Accumulated Value 10,000 10,207 11,029   11,924 13,008
Russell 2500 Index [Member]            
Account Value [Line Items]            
Line Graph and Table Measure Name       Russell 2500 Index    
Accumulated Value $ 10,000 $ 9,946 $ 10,860   $ 12,131 $ 13,634