Alger Mid 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 Midcap Growth Index (reflects no deductions for fees, expenses or taxes)[Member] | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 8.66% | 6.65% | 13.18% | ||
| 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 | 17.28% | 3.44% | 13.24% | ||
| Performance Inception Date | Oct. 14, 2016 | ||||
| Class Z-2 | After Taxes on Distributions | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 17.28% | 0.59% | 10.60% | ||
| Class Z-2 | After Taxes on Distributions and Sales | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 10.23% | 1.88% | 10.12% |