Regulatory Capital Requirements (Narrative) (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Our Other Broker-Dealer Subsidiaries | ||
| Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] | ||
| Ratio of indebtedness to net capital | 15 | |
| Stifel Nicolaus [Member] | ||
| Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] | ||
| Aggregate debit balances | 51.50% | 37.70% |
| Net capital | $ 814.8 | $ 559.5 |
| Excess of minimum required net capital | 783.2 | $ 529.8 |
| Stifel Financial Corp. [Member] | ||
| Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] | ||
| Net capital under the alternative method | $ 1.0 | |
| Aggregate debit balances | 2.00% |