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Debt Securities (Amortized Cost, Unrealized Gains And Losses, And Fair Value Of Investment Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Debt and Equity Securities, FV-NI [Line Items]
Available-for-sale securities, amortized cost	$ 8,682,214	$ 8,858,329
Available-for-sale securities, unrealized gains	28,998	7,808
Available-for-sale securities, unrealized losses	(482,407)	(591,522)
Available for sale, at fair value	8,228,805	8,274,615
Investment securities held to maturity	2,057	2,101
Held-to-maturity securities, unrealized gains	588	602
Held-to-maturity securities, unrealized losses	0	0
Held-to-maturity securities, fair value	2,645	2,703
U.S. Treasury and agencies
Debt and Equity Securities, FV-NI [Line Items]
Available-for-sale securities, amortized cost	1,426,351	1,495,542
Available-for-sale securities, unrealized gains	4,536	1,092
Available-for-sale securities, unrealized losses	(57,854)	(73,847)
Available for sale, at fair value	1,373,033	1,422,787
Obligations of states and political subdivisions
Debt and Equity Securities, FV-NI [Line Items]
Available-for-sale securities, amortized cost	1,051,171	1,055,535
Available-for-sale securities, unrealized gains	2,735	2,779
Available-for-sale securities, unrealized losses	(33,064)	(32,261)
Available for sale, at fair value	1,020,842	1,026,053
Mortgage-backed securities and collateralized mortgage obligations
Debt and Equity Securities, FV-NI [Line Items]
Available-for-sale securities, amortized cost	6,204,692	6,307,252
Available-for-sale securities, unrealized gains	21,727	3,937
Available-for-sale securities, unrealized losses	(391,489)	(485,414)
Available for sale, at fair value	5,834,930	5,825,775
Investment securities held to maturity	2,057	2,101
Held-to-maturity securities, unrealized gains	588	602
Held-to-maturity securities, unrealized losses	0	0
Held-to-maturity securities, fair value	$ 2,645	$ 2,703

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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).

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