Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total other comprehensive income (loss)	$ 57,909	$ 163,283	$ 163,216	$ 142,050
Income tax benefit (expense)	(12,161)	(34,289)	(34,275)	(29,830)
Other comprehensive income (loss), net of tax	45,748	128,994	128,941	112,220
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications before tax	235,061	254,296	715,831	734,001
Income tax benefit (expense)	(43,966)	(54,327)	(146,794)	(155,707)
Total reclassifications, net of tax	191,095	199,969	569,037	578,294
Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications before tax	(994)	(3,050)	(15,203)	(16,447)
Income tax benefit (expense)	209	640	3,193	3,453
Total reclassifications, net of tax	(785)	(2,410)	(12,010)	(12,994)
Accumulated other comprehensive income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other comprehensive income (loss), net of tax	45,748	128,994	128,941	112,220
Net unrealized gains and (losses) on available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total other comprehensive income (loss)	56,568	162,601	158,079	140,005
Income tax benefit (expense)	(11,879)	(34,146)	(33,196)	(29,401)
Other comprehensive income (loss), net of tax	44,689	128,455	124,883	110,604
Net unrealized gains and (losses) on available-for-sale securities | Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications before tax	347	(2,368)	(10,066)	(14,402)
Income tax benefit (expense)	(73)	497	2,114	3,024
Total reclassifications, net of tax	274	(1,871)	(7,952)	(11,378)
Net benefit plan assets and (obligations) recognized in shareholders' equity
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total other comprehensive income (loss)	1,341	682	5,137	2,045
Income tax benefit (expense)	(282)	(143)	(1,079)	(429)
Other comprehensive income (loss), net of tax	1,059	539	4,058	1,616
Net benefit plan assets and (obligations) recognized in shareholders' equity | Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications before tax	(1,341)	(682)	(5,137)	(2,045)
Income tax benefit (expense)	282	143	1,079	429
Total reclassifications, net of tax	$ (1,059)	$ (539)	$ (4,058)	$ (1,616)