Alger Small Cap Focus Fund Average Annual Total Returns - Class I Shares [Member] |
12 Months Ended | 21 Months Ended | 60 Months Ended | 79 Months Ended | 120 Months Ended | |
|---|---|---|---|---|---|---|
Oct. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| Russell 2000 Growth Index (reflects no deductions for fees, expenses or taxes)[Member] | ||||||
| Prospectus [Line Items] | ||||||
| Average Annual Return, Percent | 13.01% | 3.18% | 9.57% | |||
| S&P 500 Index (reflects no deductions for fees, expenses or taxes)[Member] | ||||||
| Prospectus [Line Items] | ||||||
| Average Annual Return, Percent | 17.88% | 19.32% | 14.42% | 15.89% | 14.82% | |
| Class I | ||||||
| Prospectus [Line Items] | ||||||
| Average Annual Return, Percent | 6.96% | (6.47%) | 8.06% | |||
| Performance Inception Date | Mar. 03, 2008 | |||||
| Class I | After Taxes on Distributions | ||||||
| Prospectus [Line Items] | ||||||
| Average Annual Return, Percent | 6.96% | (6.77%) | 7.76% | |||
| Class I | After Taxes on Distributions and Sales | ||||||
| Prospectus [Line Items] | ||||||
| Average Annual Return, Percent | 4.12% | (4.73%) | 6.57% |