Federal and State Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets [Abstract]
Available for sale securities mark to market	$ 255,244	$ 0
Credit loss reserves	69,385	67,339
Lease liability	49,839	48,457
Deferred compensation	34,645	33,945
Unearned fees	12,915	11,368
Purchased loan discount	4,955	7,498
Share-based compensation	4,625	5,989
Valuation adjustments	5,792	1,883
Other	42,808	28,958
Total deferred tax assets	480,208	205,437
Valuation Allowance [Abstract]
Valuation allowance	0	0
Deferred tax liabilities [Abstract]
Right-of-use asset	40,741	41,291
Mortgage servicing rights	49,001	31,703
Available for sale securities mark to market	0	21,841
Acquired identifiable intangible	11,280	14,307
Depreciation	7,163	10,939
Lease financing	12,333	11,120
Other	38,357	39,698
Total deferred tax liabilities	158,875	170,899
Net deferred tax assets, net	321,333	34,538
Current income tax expense [Abstract]
Federal	127,144	121,196	$ 173,888
State	18,185	21,065	29,889
Total current income tax expense	145,329	142,261	203,777
Deferred income tax expense [Abstract]
Federal	(4,700)	29,777	(65,989)
State	(765)	7,737	(8,995)
Total deferred income tax expense (benefit)	(5,465)	37,514	(74,984)
Total income tax expense	139,864	179,775	128,793
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory tax	138,633	167,181	118,412
Tax exempt revenue	(5,714)	(6,084)	(7,035)
Effect of state income taxes, net of federal benefit	13,490	22,489	14,251
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	(8,883)	(8,801)	(6,994)
Other, net	2,338	4,990	10,159
Total income tax expense	$ 139,864	$ 179,775	$ 128,793
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory tax (in thousandths)	21.00%	21.00%	21.00%
Tax exempt revenue (in thousandths)	(0.80%)	(0.70%)	(1.20%)
Effect of state income taxes, net of federal benefit (in thousandths)	2.00%	2.80%	2.50%
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments (in thousandths)	(1.40%)	(1.10%)	(1.20%)
Other, net (in thousandths)	0.40%	0.60%	1.70%
Total (in thousandths)	21.20%	22.60%	22.80%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1	$ 21,092	$ 22,902	$ 20,465
Additions for tax for current year positions	3,465	3,961	6,384
Settlements during the period	0	(1,754)	0
Lapses of applicable statute of limitations	(4,974)	(4,017)	(3,947)
Balance as of December 31	19,583	21,092	22,902
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	15,300
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	1,800	2,300	$ 2,400
Unrecognized Tax Benefits, Penalties and Interest Accrued	$ 6,000	$ 6,400
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, Federal	3
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, State, Minimum	3
Unrecognized Tax Benefits, Number of Reporting Periods Open for Examination, State, Maximum	6