Alger Mid Cap Growth Institutional Fund Average Annual Total Returns - Class I R Shares [Member] |
12 Months Ended | 60 Months Ended | 120 Months Ended | |
|---|---|---|---|---|
Oct. 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% | 12.49% | |
| S&P 500 Index (reflects no deductions for fees, expenses or taxes)[Member] | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 17.88% | 14.42% | 14.82% | |
| Class I | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 17.01% | 3.09% | 11.63% | |
| Performance Inception Date | Nov. 08, 1993 | |||
| Class I | After Taxes on Distributions | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 17.01% | 0.20% | 9.19% | |
| Class I | After Taxes on Distributions and Sales | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 10.07% | 1.61% | 8.84% | |
| Class R | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 16.24% | 2.56% | 11.05% | |
| Performance Inception Date | Jan. 27, 2003 |