Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Deferred tax assets:
Allowance for credit losses	$ 157,629	$ 128,717
Employee benefits	41,808	41,190
Investment securities	48,652	42,361
Net operating loss carryforwards	9,078	11,037
Purchase accounting	42,637	53,980
FDIC special assessment	10,673	13,894
Other	23,744	24,362
Total deferred tax assets	334,221	315,541
Deferred tax liabilities:
Pension plans	52,783	37,194
Depreciation	12,314	20,963
Other investments	17,088	11,175
Core deposit intangibles	21,287	28,237
Other	25,876	22,319
Total deferred tax liabilities	129,348	119,888
Valuation allowance	1,263	424
Net deferred tax asset (included in other assets)	$ 203,610	$ 195,229