Shareholder Report, Line Graph (Details) 462680_Jacob Small Cap Growth Fund_Investor Class_TSR Annual {Investor Class} - USD ($) |
12 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Aug. 31, 2025 |
Aug. 31, 2024 |
Aug. 31, 2023 |
Aug. 31, 2022 |
Aug. 31, 2021 |
Aug. 31, 2020 |
Aug. 31, 2019 |
Aug. 31, 2018 |
Aug. 31, 2017 |
Aug. 31, 2016 |
Aug. 31, 2026 |
|
| Investor Class | |||||||||||
| Account Value [Line Items] | |||||||||||
| Accumulated Value | $ 22,537 | $ 15,581 | $ 13,492 | $ 13,996 | $ 30,361 | $ 18,788 | $ 14,256 | $ 17,043 | $ 10,986 | $ 10,000 | $ 20,045 |
| S&P 500 TR [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | S&P 500 TR | ||||||||||
| Accumulated Value | 34,718 | 29,960 | 23,566 | 20,325 | 22,895 | 17,455 | 14,315 | 13,909 | 11,623 | 10,000 | $ 41,793 |
| Bloomberg US 2000 Growth Total Return Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Bloomberg US 2000 Growth Total Return Index | ||||||||||
| Accumulated Value | $ 22,786 | $ 20,665 | $ 17,590 | $ 16,955 | $ 22,594 | $ 15,550 | $ 13,526 | $ 15,129 | $ 11,519 | $ 10,000 | $ 28,368 |