Financial Instruments with Off-Balance Sheet Risk (Details) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended |
|---|---|---|
Mar. 31, 2024 |
Dec. 31, 2023 |
|
| Financial Instruments with Off-Balance Sheet Risk [Abstract] | ||
| Margin loans extended | $ 352.0 | $ 338.1 |
| Receivables from customers | 74.7 | 72.8 |
| Unsettled customer transactions |