Cash and Cash Equivalents and Restricted Cash - Summary of Reconciliation of Cash and Cash Equivalents with Restricted or Segregated Cash (Detail) - USD ($) $ in Thousands |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Cash And Cash Equivalents [Line Items] | ||
| Cash and cash equivalents | $ 377,302 | $ 519,734 |
| Cash segregated for regulatory purposes | 49,053 | 48,722 |
| Total | 548,236 | 675,851 |
| Cash and Cash Equivalents [Member] | ||
| Cash And Cash Equivalents [Line Items] | ||
| Cash and cash equivalents | 377,302 | 519,734 |
| Cash Segregated under Federal Regulations [Member] | ||
| Cash And Cash Equivalents [Line Items] | ||
| Cash segregated for regulatory purposes | 49,053 | 48,722 |
| Receivables from Broker-Dealers, Clearing Organizations and Customers [Member] | ||
| Cash And Cash Equivalents [Line Items] | ||
| Restricted cash deposits with clearing organizations and broker-dealers | 120,471 | 107,223 |
| Prepaid Expenses and Other Assets [Member] | ||
| Cash And Cash Equivalents [Line Items] | ||
| Other restricted cash deposits | $ 1,410 | $ 172 |