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Securities - Schedule of Changes in Equity Securities Without Readily Determinable Fair Values (Detail) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2026 | Mar. 31, 2025
Equity Securities, FV-NI and without Readily Determinable Fair Value [Abstract] |  |
Beginning balance | $ 524,112 | $ 416,750
Acquisition of HTLF |  | 121,769
Purchases of securities | 33,664 | 24,003
Observable upward price adjustments | 3,568 | 1,022
Observable downward price adjustments | (636) | (6,273)
Sales of securities and other activity | (25,382) | (17,341)
Ending balance | $ 535,326 | $ 539,930

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- Definition Equity securities without readily determinable fair value, purchases of securities. + References No definition available. + Details
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- Definition Equity securities without readily determinable fair value, sales of securities and other activity. + References No definition available. + Details
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- Definition Amount of investment in equity security without readily determinable fair value. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 321 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479536/321-10-50-3 + Details
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- Definition Amount of loss from downward price adjustment on investment in equity security without readily determinable fair value. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 321 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479536/321-10-50-3 + Details
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- Definition Amount of gain from upward price adjustment on investment in equity security without readily determinable fair value. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 321 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479536/321-10-50-3 + Details
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