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Collateralized Transactions - Additional Information (Detail) - USD ($) | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Securities Financing Transaction [Line Items] |  |
Securities loaned |  | $ 13,902,000
CF & Co [Member] |  |
Securities Financing Transaction [Line Items] |  |
Repurchase agreements | $ 0 | 0
Securities loaned | $ 0 | $ 13,900,000
Stated interest rate |  | 2.45%
CF & Co [Member] | Securities Financing Transaction, Fair Value [Member] |  |
Securities Financing Transaction [Line Items] |  |
Securities loaned |  | $ 13,900,000
CF & Co [Member] | Securities Financing Transaction, Fair Value [Member] | Fair Value [Member] |  |
Securities Financing Transaction [Line Items] |  |
Securities loaned |  | $ 13,900,000

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