Alger Spectra Fund Average Annual Total Returns - Class Z Shares [Member] |
12 Months Ended | 60 Months Ended | 111 Months Ended | 120 Months Ended | |
|---|---|---|---|---|---|
Oct. 31, 2025 |
Dec. 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% | 15.43% | 14.82% | |
| Class Z | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 29.86% | 13.22% | 16.62% | ||
| Performance Inception Date | Dec. 29, 2010 | ||||
| Class Z | After Taxes on Distributions | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 27.80% | 11.10% | 14.61% | ||
| Class Z | After Taxes on Distributions and Sales | |||||
| Prospectus [Line Items] | |||||
| Average Annual Return, Percent | 19.04% | 10.04% | 13.38% |