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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, 2021 | Dec. 31, 2020
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Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | $ 1,199,386 | $ 694,028
U.S. Government Agency Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 182,636 | 56,450
Corporate Fixed Income Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 318,288 | 194,575
Corporate Equity Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 91,874 | 67,593
State and Municipal Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 162,821 | 96,150
Loans [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 18,854 |
U.S. Government Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 16,829 | 46,900
Sovereign Debt [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 9,920 |
Securities Sold, But Not yet Purchased [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Financial instruments owned, at fair value |  | 721,028 | 437,978
Other | [1] | 8,147 | 11,303
Securities Sold, But Not yet Purchased [Member] | U.S. Government Agency Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | 44,638 |
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 |  | 161,529 | 162,626
Securities Sold, But Not yet Purchased [Member] | Corporate Equity Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Equity securities |  | 30,813 | 30,848
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 |  | 366,014 | 91,974
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 |  | 109,887 | 141,227
Securities Owned [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Asset-backed securities |  | 74,783 | 3,394
Financial instruments owned, at fair value |  | 1,199,386 | 694,028
Securities Owned [Member] | U.S. Government Agency Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | 182,636 | 56,450
Securities Owned [Member] | Corporate Fixed Income Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Fixed income securities |  | 318,288 | 194,575
Securities Owned [Member] | Corporate Equity Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Equity securities |  | 91,874 | 67,593
Securities Owned [Member] | State and Municipal Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
State and municipal securities |  | 162,821 | 96,150
Securities Owned [Member] | Loans [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Fixed income securities |  | 18,854 | 11,275
Securities Owned [Member] | U.S. Government Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | 16,829 | 46,900
Securities Owned [Member] | Mortgage-Backed Securities [Member] | Agency Securities [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | 303,684 | 216,434
Securities Owned [Member] | Mortgage-Backed Securities [Member] | Non-Agency [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Trading securities owned |  | 19,697 | 107
Securities Owned [Member] | Sovereign Debt [Member] |  |  |
Schedule Of Trading Securities And Other Trading Assets [Line Items] |  |  |
Sovereign debt |  | $ 9,920 | $ 1,150
[1] | Includes sovereign debt and state and municipal securities

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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 Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
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