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Securities - Sales of Securities Available for Sale (Detail) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
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Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Investments, Debt and Equity Securities [Abstract] |  |  |  |
Proceeds from sales | $ 51,250 | $ 2,346,626 | $ 1,162,352 | $ 3,291,529
Gross realized gains | 0 | 803 | 108,989 | 803
Gross realized losses | 0 | (634) | 0 | (634)
Tax (expense)benefit of securities gains/losses | $ 0 | $ (35) | $ (22,888) | $ (35)

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- Definition This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References No definition available. + Details
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- Definition This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. + References No definition available. + Details
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- Definition The cash inflow associated with the sale of debt and equity securities classified as available-for-sale securities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26853-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585 + Details
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