S000037763 [Member] Expense Example - William Blair International Leaders Fund |
Dec. 31, 2025
USD ($)
|
|---|---|
| Class N | |
| Prospectus [Line Items] | |
| Expense Example, with Redemption, 1 Year | $ 117 |
| Expense Example, with Redemption, 3 Years | 391 |
| Expense Example, with Redemption, 5 Years | 685 |
| Expense Example, with Redemption, 10 Years | 1,523 |
| Class I | |
| Prospectus [Line Items] | |
| Expense Example, with Redemption, 1 Year | 92 |
| Expense Example, with Redemption, 3 Years | 315 |
| Expense Example, with Redemption, 5 Years | 556 |
| Expense Example, with Redemption, 10 Years | 1,248 |
| Class R6 | |
| Prospectus [Line Items] | |
| Expense Example, with Redemption, 1 Year | 87 |
| Expense Example, with Redemption, 3 Years | 284 |
| Expense Example, with Redemption, 5 Years | 498 |
| Expense Example, with Redemption, 10 Years | $ 1,114 |