Investment Securities - Amortized cost and fair value for available for sale securities (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Investment securities held-to-maturity
Amortized cost	$ 2,145,991	$ 2,254,670
Gross Unrealized Losses	(364,243)	(420,143)
Fair Value	1,781,748	1,834,527
Investment securities available for sale
Amortized cost	6,426,702	5,129,216
Gross Unrealized Gains	22,281	701
Gross Unrealized Losses	(521,116)	(809,324)
Fair Value	5,927,867	4,320,593
U.S. Treasuries
Investment securities available for sale
Amortized cost		10,654
Gross Unrealized Gains		2
Fair Value		10,656
U.S. Government agencies
Investment securities held-to-maturity
Amortized cost	132,910	147,272
Gross Unrealized Losses	(19,050)	(23,498)
Fair Value	113,860	123,774
Investment securities available for sale
Amortized cost		169,207
Gross Unrealized Losses		(18,789)
Fair Value		150,418
Residential mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Investment securities held-to-maturity
Amortized cost	1,226,097	1,297,543
Gross Unrealized Losses	(209,197)	(241,204)
Fair Value	1,016,900	1,056,339
Investment securities available for sale
Amortized cost	1,687,317	1,659,851
Gross Unrealized Gains	3,839	97
Gross Unrealized Losses	(167,277)	(282,423)
Fair Value	1,523,879	1,377,525
Residential collateralized mortgage-obligations issued by U.S. government agencies or sponsored enterprises
Investment securities held-to-maturity
Amortized cost	395,349	411,721
Gross Unrealized Losses	(62,090)	(72,057)
Fair Value	333,259	339,664
Investment securities available for sale
Amortized cost	2,336,853	557,288
Gross Unrealized Gains	15,927	19
Gross Unrealized Losses	(55,809)	(98,212)
Fair Value	2,296,971	459,095
Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Investment securities held-to-maturity
Amortized cost	343,953	348,338
Gross Unrealized Losses	(64,067)	(72,391)
Fair Value	279,886	275,947
Investment securities available for sale
Amortized cost	661,425	1,234,573
Gross Unrealized Gains	1,787	562
Gross Unrealized Losses	(81,720)	(194,580)
Fair Value	581,492	1,040,555
State and municipal obligations
Investment securities available for sale
Amortized cost	1,108,538	1,117,330
Gross Unrealized Gains	92	2
Gross Unrealized Losses	(186,213)	(171,609)
Fair Value	922,417	945,723
Small Business Administration loan-backed securities
Investment securities held-to-maturity
Amortized cost	47,682	49,796
Gross Unrealized Losses	(9,839)	(10,993)
Fair Value	37,843	38,803
Investment securities available for sale
Amortized cost	604,070	351,814
Gross Unrealized Gains	636	19
Gross Unrealized Losses	(28,192)	(41,721)
Fair Value	576,514	310,112
Corporate securities
Investment securities available for sale
Amortized cost	28,499	28,499
Gross Unrealized Losses	(1,905)	(1,990)
Fair Value	$ 26,594	$ 26,509

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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Amount, before tax, of unrealized loss 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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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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