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Securities - Schedule of Components of Investment Securities (Losses) Gains, Net (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Available-for-sale debt securities: |  |  |  |
Gains realized on sales | $ 1,060 | $ 311 | $ 5,080 | $ 5,715
Losses realized on sales | (2) |  | (2) | (171)
Equity securities with readily determinable fair values: |  |  |  |
Fair value adjustments, net | (4,427) | 84 | (9,607) | 84
Equity securities without readily determinable fair values: |  |  |  |
Fair value adjustments, net | (141) | (870) | 8,138 | 1,996
Total investment securities (losses) gains, net | $ (3,510) | $ (475) | $ 3,609 | $ 7,624

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