Alger Small Cap Growth Institutional Fund Average Annual Total Returns - Class Z2 Shares [Member] |
12 Months Ended | 60 Months Ended | 111 Months Ended | 113 Months Ended | |
|---|---|---|---|---|---|
Oct. 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% | 9.62% | ||
| S&P 500 Index (reflects no deductions for fees, expenses or taxes)[Member] | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 17.88% | 14.42% | 15.43% | 14.92% | |
| Class Z-2 | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 5.30% | (4.92%) | 9.20% | ||
| Performance Inception Date | Aug. 01, 2016 | ||||
| Class Z-2 | After Taxes on Distributions | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 4.63% | (5.99%) | 7.48% | ||
| Class Z-2 | After Taxes on Distributions and Sales | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 3.60% | (3.55%) | 7.39% |