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Investment Securities - Hedge Funds and Private Equity Funds (Details) $ in Millions | Mar. 31, 2021 USD ($) fund | Dec. 31, 2020 USD ($)
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Private equity funds |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Number of investments | 13 |
Hedge and private equity funds included in other long-term investments |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Largest single fund investment | $ | $ 23.5 | $ 29.1
Hedge funds |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Number of investments | 1 |

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