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Financial Instruments Owned and Financial Instruments Sold, But Not Yet Purchased (Components of Trading Securities Owned and Trading Securities Sold, But Not Yet Purchased) (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
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Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | $ 1,540,478 | $ 1,169,008
Securities Sold, But Not yet Purchased [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 1,540,478 | 1,169,008
Securities Sold, But Not yet Purchased [Member] | Corporate Fixed Income Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Fixed income securities |  | 153,144 | 174,425
Securities Sold, But Not yet Purchased [Member] | Corporate Equity Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 116,835 | 34,437
Securities Sold, But Not yet Purchased [Member] | Syndicated Loans [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 1,235 | 1,090
Securities Sold, But Not yet Purchased [Member] | U.S. Government Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | 366,214 | 370,373
Securities Sold, But Not yet Purchased [Member] | Mortgage-Backed Securities [Member] | Agency Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | 168,692 | 65,946
Securities Owned [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Asset-backed securities |  | 60,135 | 113,033
Other | [1] | 66,208 | 69,486
Financial instruments owned, at fair value |  | 806,120 | 646,271
Securities Owned [Member] | U.S. Government Agency Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | 275,046 | 149,479
Securities Owned [Member] | Corporate Fixed Income Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Fixed income securities |  | 311,339 | 274,207
Securities Owned [Member] | Corporate Equity Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 123,932 | 50,787
Securities Owned [Member] | State and Municipal Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
State and municipal securities |  | 241,755 | 229,342
Securities Owned [Member] | U.S. Government Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | 15,370 | 20,045
Securities Owned [Member] | Mortgage-Backed Securities [Member] | Agency Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | $ 446,693 | $ 262,629
[1] | Includes syndicated loans, non-agency mortgage-backed securities, and sovereign debt.

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- Definition Investments in notes or bonds that are collateralized by a specific group of underlying assets owned by the issuer of the notes or bonds which are short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months. + References No definition available. + Details
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- Definition Fair value of firm holdings in securities classified as other. Includes pledged and unpledged holdings. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 940 -SubTopic 320 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479035/940-320-45-2 + Details
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- Definition Fair value of obligations arising from corporate debt obligations sold short. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 940 -SubTopic 320 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479035/940-320-45-2 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6B -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6B + Details
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