Other Comprehensive Income (Loss) - Pretax and Related Income Tax Benefit (Expense) Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications	$ 968,709	$ 902,229	$ 1,090,034
Income tax benefit (expense)	(205,715)	(189,280)	(224,685)
Net income	762,994	712,949	865,349
Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications	(17,994)	(41,090)	(26,610)
Income tax benefit (expense)	3,778	8,629	5,588
Net income	(14,216)	(32,461)	(21,022)
Reclassification from Accumulated Other Comprehensive Income | Net unrealized gains and losses on available-for-sale securities
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications	(15,069)	(27,100)	(9,860)
Income tax benefit (expense)	3,164	5,691	2,070
Net income	(11,905)	(21,409)	(7,790)
Reclassification from Accumulated Other Comprehensive Income | Net benefit plan assets and obligations recognized in shareholders' equity
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications	(2,925)	(13,990)	(16,750)
Income tax benefit (expense)	614	2,938	3,518
Net income	$ (2,311)	$ (11,052)	$ (13,232)