Alger Spectra Fund Average Annual Total Returns - Class A C 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 A | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 22.60% | 11.64% | 15.61% | |
| Performance Inception Date | Dec. 31, 1974 | |||
| Class A | After Taxes on Distributions | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 20.49% | 9.42% | 13.53% | |
| Class A | After Taxes on Distributions and Sales | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 14.77% | 8.71% | 12.46% | |
| Class C | ||||
| Prospectus [Line Items] | ||||
| Average Annual Return, Percent | 27.39% | 11.99% | 15.53% | |
| Performance Inception Date | Sep. 24, 2008 |