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Investment Securities (Amortized Cost, Unrealized Gains And Losses, And Fair Value Of Investment Securities) (Details) - USD ($) $ in Thousands | Mar. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Debt and Equity Securities, FV-NI [Line Items] |  |
Available-for-sale securities, amortized cost | $ 9,172,126 | $ 9,262,777
Available-for-sale securities, unrealized gains | 12,306 | 55,201
Available-for-sale securities, unrealized losses | (567,887) | (488,108)
Available for sale, at fair value | 8,616,545 | 8,829,870
Investment securities held to maturity | 2,247 | 2,300
Held-to-maturity securities, unrealized gains | 692 | 725
Held-to-maturity securities, unrealized losses | 0 | 0
Held-to-maturity securities, fair value | 2,939 | 3,025
U.S. Treasury and agencies |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Available-for-sale securities, amortized cost | 1,552,240 | 1,551,074
Available-for-sale securities, unrealized gains | 1,132 | 6,192
Available-for-sale securities, unrealized losses | (85,979) | (78,874)
Available for sale, at fair value | 1,467,393 | 1,478,392
Obligations of states and political subdivisions |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Available-for-sale securities, amortized cost | 1,068,290 | 1,073,264
Available-for-sale securities, unrealized gains | 8,788 | 20,451
Available-for-sale securities, unrealized losses | (25,149) | (21,610)
Available for sale, at fair value | 1,051,929 | 1,072,105
Mortgage-backed securities and collateralized mortgage obligations |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Available-for-sale securities, amortized cost | 6,551,596 | 6,638,439
Available-for-sale securities, unrealized gains | 2,386 | 28,558
Available-for-sale securities, unrealized losses | (456,759) | (387,624)
Available for sale, at fair value | 6,097,223 | 6,279,373
Investment securities held to maturity | 2,247 | 2,300
Held-to-maturity securities, unrealized gains | 692 | 725
Held-to-maturity securities, unrealized losses | 0 | 0
Held-to-maturity securities, fair value | $ 2,939 | $ 3,025

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 + Details
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