Alger Mid 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 Midcap Growth Index (reflects no deductions for fees, expenses or taxes)[Member] | ||||||
| Prospectus [Line Items] | ||||||
| Average Annual Return, Percent | 8.66% | 6.65% | 11.56% | |||
| 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 | 14.95% | 3.96% | 13.64% | |||
| Performance Inception Date | Jun. 14, 2019 | |||||
| Class I | After Taxes on Distributions | ||||||
| Prospectus [Line Items] | ||||||
| Average Annual Return, Percent | 14.95% | 3.14% | 12.88% | |||
| Class I | After Taxes on Distributions and Sales | ||||||
| Prospectus [Line Items] | ||||||
| Average Annual Return, Percent | 8.85% | 2.72% | 10.80% |