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v3.21.1

Investment Securities - Additional Information (Detail) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2021 USD ($) security | Mar. 31, 2020 USD ($) | Dec. 31, 2020 USD ($)
Summary of Investment Holdings [Line Items] |  |  |
Accrued interest receivable | $ 26,100,000 |  | $ 27,000,000.0
Number of securities in security portfolio | security | 1,892 |  |
Number of securities in unrealized loss position | security | 280 |  |
Total investment securities - available-for-sale | $ 6,724,530,000 |  | 5,970,115,000
Unrealized losses | 82,422,000 |  | 11,385,000
Equity securities, at fair value | 2,429,000 |  | 2,547,000
Gains on equity securities | 100,000 | $ 100,000 |
Impairments on equity securities without readily determinable fair value | 0 | 0 |
Other Assets [Member] |  |  |
Summary of Investment Holdings [Line Items] |  |  |
Equity securities without readily determinable fair value | $ 117,200,000 |  | 105,800,000
Pooled trust preferred securities |  |  |
Summary of Investment Holdings [Line Items] |  |  |
Number of pooled trust preferred securities | security | 2 |  |
Total investment securities - available-for-sale | $ 8,210,000 |  | 7,913,000
Unrealized losses | 5,543,000 |  | $ 5,850,000
Other-than-temporary impairment loss | $ 0 | $ 0 |

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