Securities - Amortized cost and fair value for available for sale securities (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Investment securities held-to-maturity
Amortized cost	$ 2,195,980	$ 2,254,670
Gross Unrealized Losses	(375,507)	(420,143)
Fair Value	1,820,473	1,834,527
Investment securities available for sale
Amortized cost	6,358,427	5,129,216
Gross Unrealized Gains	13,016	701
Gross Unrealized Losses	(518,074)	(809,324)
Fair Value	5,853,369	4,320,593
U.S. Treasuries
Investment securities available for sale
Amortized cost	18,294	10,654
Gross Unrealized Gains		2
Gross Unrealized Losses	(1)
Fair Value	18,293	10,656
U.S. Government agencies
Investment securities held-to-maturity
Amortized cost	132,908	147,272
Gross Unrealized Losses	(20,361)	(23,498)
Fair Value	112,547	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	1,262,776	1,297,543
Gross Unrealized Losses	(214,924)	(241,204)
Fair Value	1,047,852	1,056,339
Investment securities available for sale
Amortized cost	1,613,205	1,659,851
Gross Unrealized Gains	3,570	97
Gross Unrealized Losses	(169,659)	(282,423)
Fair Value	1,447,116	1,377,525
Residential collateralized mortgage-obligations issued by U.S. government agencies or sponsored enterprises
Investment securities held-to-maturity
Amortized cost	405,003	411,721
Gross Unrealized Losses	(63,798)	(72,057)
Fair Value	341,205	339,664
Investment securities available for sale
Amortized cost	2,397,132	557,288
Gross Unrealized Gains	7,758	19
Gross Unrealized Losses	(57,756)	(98,212)
Fair Value	2,347,134	459,095
Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises
Investment securities held-to-maturity
Amortized cost	346,083	348,338
Gross Unrealized Losses	(66,345)	(72,391)
Fair Value	279,738	275,947
Investment securities available for sale
Amortized cost	643,484	1,234,573
Gross Unrealized Gains	1,396	562
Gross Unrealized Losses	(84,246)	(194,580)
Fair Value	560,634	1,040,555
State and municipal obligations
Investment securities available for sale
Amortized cost	1,085,891	1,117,330
Gross Unrealized Gains	22	2
Gross Unrealized Losses	(175,264)	(171,609)
Fair Value	910,649	945,723
Small Business Administration loan-backed securities
Investment securities held-to-maturity
Amortized cost	49,210	49,796
Gross Unrealized Losses	(10,079)	(10,993)
Fair Value	39,131	38,803
Investment securities available for sale
Amortized cost	571,923	351,814
Gross Unrealized Gains	270	19
Gross Unrealized Losses	(29,640)	(41,721)
Fair Value	542,553	310,112
Corporate securities
Investment securities available for sale
Amortized cost	28,498	28,499
Gross Unrealized Losses	(1,508)	(1,990)
Fair Value	$ 26,990	$ 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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