Alger Spectra Fund Average Annual Total Returns - Class I Shares [Member] |
12 Months Ended | 60 Months Ended | 120 Months Ended | |
|---|---|---|---|---|
Oct. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| Russell 3000 Growth Index (reflects no deductions for fees, expenses or taxes)[Member] | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 18.15% | 14.59% | 17.59% | |
| 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 | 29.38% | 12.86% | 16.25% | |
| Performance Inception Date | Sep. 24, 2008 | |||
| Class I | After Taxes on Distributions | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 27.20% | 10.65% | 14.19% | |
| Class I | After Taxes on Distributions and Sales | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 18.84% | 9.72% | 13.05% |