v3.26.1
Average Annual Total Returns
 12 Months Ended 60 Months Ended 120 Months Ended
Jul. 29, 2026
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Russell 3000® Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Russell 3000® Index(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent   17.15% 13.15% 14.29%
Russell 1000® Growth Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] [1] Russell 1000® Growth Index*(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent [1]   18.56% 15.32% 18.13%
Russell 2000® Growth Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] [2] Russell 2000® Growth Index*(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent   13.01% [3] 3.18% [2] 9.57% [3]
Russell 3000® Growth Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] [4] Russell 3000® Growth Index*(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent [4]   18.15% 14.59% 17.59%
Russell 1000® Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] [5] Russell 1000® Index*(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent [5]   17.37% 13.59% 14.59%
Bloomberg Universal Bond Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Bloomberg U.S. Universal Bond Index(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent   7.58% 0.06% 2.44%
ICE BofA US High Yield® Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] [6] ICE BofA US High Yield Index*(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent [6]   8.59% 4.55% 6.48%
FTSE Global All Cap ex US Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] FTSE Global All Cap ex US Index(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent   32.37% 8.38% 8.88%
FTSE All-World ex US Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] [7] FTSE All-World ex US Index*(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent [7]   32.59% 8.54% 9.01%
Russell Midcap® Growth Index (reflects no deduction for fees, expenses or taxes)        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] [8] Russell Midcap® Growth Index*(reflects no deduction for fees, expenses, or taxes)      
Average Annual Return, Percent   8.66% [9] 6.65% [9] 12.49% [8]
Buffalo Blue Chip Growth Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   16.25% 13.62% 15.42%
Buffalo Blue Chip Growth Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   14.46% 11.76% 14.02%
Buffalo Blue Chip Growth Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   10.82% 10.50% 12.60%
Buffalo Blue Chip Growth Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   16.42% 13.76% 15.58%
Buffalo Early Stage Growth Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   3.12% (1.89%) 9.33%
Buffalo Early Stage Growth Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   1.91% (3.00%) 7.08%
Buffalo Early Stage Growth Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   2.68% (1.52%) 6.96%
Buffalo Early Stage Growth Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   3.28% (1.78%) 9.48%
Buffalo Flexible Allocation Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   10.39% 12.07% 9.04%
Buffalo Flexible Allocation Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   8.15% 10.72% 7.84%
Buffalo Flexible Allocation Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   7.72% 9.48% 7.11%
Buffalo Flexible Allocation Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   10.51% 12.23% 9.19%
Buffalo Growth Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   13.92% 11.26% 14.09%
Buffalo Growth Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   12.37% 9.53% 11.42%
Buffalo Growth Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   9.37% 8.65% 10.77%
Buffalo Growth Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   14.04% 11.39% 14.24%
Buffalo Growth & Income Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   8.40% 11.53% 12.43%
Buffalo Growth & Income Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   8.06% 11.04% 11.89%
Buffalo Growth & Income Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   5.18% 9.09% 10.21%
Buffalo Growth & Income Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   8.54% 11.69% 12.60%
Buffalo High Yield Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   5.11% 5.13% 5.70%
Buffalo High Yield Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   2.28% 2.24% 3.23%
Buffalo High Yield Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   3.01% 2.70% 3.34%
Buffalo High Yield Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   5.26% 5.28% 5.85%
Buffalo International Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   17.08% 4.68% 8.83%
Buffalo International Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   17.00% 4.54% 8.73%
Buffalo International Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   10.43% 3.74% 7.35%
Buffalo International Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   17.28% 4.84% 8.99%
Buffalo Mid Cap Discovery Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   (1.80%) 0.54% 8.40%
Buffalo Mid Cap Discovery Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   (5.83%) (1.90%) 6.08%
Buffalo Mid Cap Discovery Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   1.89% 0.20% 6.41%
Buffalo Mid Cap Discovery Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   (1.65%) 0.68% 8.56%
Buffalo Mid Cap Growth Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   (1.66%) 1.99% 8.59%
Buffalo Mid Cap Growth Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   (3.83%) 0.15% 6.33%
Buffalo Mid Cap Growth Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   0.59% 1.42% 6.48%
Buffalo Mid Cap Growth Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   (1.52%) 2.12% 8.74%
Buffalo Small Cap Growth Fund Investor Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   (0.13%) (4.02%) 9.28%
Buffalo Small Cap Growth Fund Investor Class | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions      
Average Annual Return, Percent   (0.13%) (4.75%) 6.55%
Buffalo Small Cap Growth Fund Investor Class | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return After Taxes on Distributions and Sale of Fund Shares      
Average Annual Return, Percent   (0.08%) (3.06%) 6.75%
Buffalo Small Cap Growth Fund Institutional Class        
Prospectus [Line Items]        
Average Annual Return, Label [Optional Text] Return Before Taxes      
Average Annual Return, Percent   (0.07%) (3.92%) 9.42%
[1] A secondary performance benchmark is provided to show how the Fund’s performance compares with the returns of an index that is more appropriate given the holdings of the Fund.
[2] A secondary performance benchmark is provided to show how the Fund’s performance compares with the returns of an index that is more appropriate given the holdings of the Fund.
[3] A secondary performance benchmark is provided to show how the Fund’s performance compares with the returns of an index that is more appropriate given the holdings of the Fund.
[4] A secondary performance benchmark is provided to show how the Fund’s performance compares with the returns of an index that is more appropriate given the holdings of the Fund.
[5] A secondary performance benchmark is provided to show how the Fund’s performance compares with the returns of an index that is more appropriate given the holdings of the Fund.
[6] A secondary performance benchmark is provided to show how the Fund’s performance compares with the returns of an index that is more appropriate given the holdings of the Fund.
[7] A secondary performance benchmark is provided to show how the Fund’s performance compares with the returns of an index that is more appropriate given the holdings of the Fund.
[8] A secondary performance benchmark is provided to show how the Fund’s performance compares with the returns of an index that is more appropriate given the holdings of the Fund.
[9] A secondary performance benchmark is provided to show how the Fund’s performance compares with the returns of an index that is more appropriate given the holdings of the Fund.