Federal and State Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets [Abstract]
Credit loss reserves	$ 67,339	$ 101,265
Lease liability	48,457	44,794
Deferred compensation	33,945	29,504
Unearned fees	11,368	14,584
Purchased loan discount	7,498	11,537
Share-based compensation	5,989	6,525
Valuation adjustments	1,883	3,834
Other	28,958	29,963
Total deferred tax assets	205,437	242,006
Valuation Allowance [Abstract]
Valuation allowance	0	0
Deferred tax liabilities [Abstract]
Available for sale securities mark to market	21,841	105,769
Right-of-use asset	41,291	38,635
Mortgage servicing rights	31,703	24,182
Acquired identifiable intangible	14,307	18,138
Depreciation	10,939	13,754
Lease financing	11,120	11,828
Other	39,698	39,210
Total deferred tax liabilities	170,899	251,516
Net deferred tax assets, net	34,538
Net deferred liabilities, net		(9,510)
Current income tax expense [Abstract]
Federal	121,196	173,888	$ 110,887
State	21,065	29,889	15,088
Total current income tax expense	142,261	203,777	125,975
Deferred income tax expense [Abstract]
Federal	29,777	(65,989)	3,416
State	7,737	(8,995)	792
Total deferred income tax expense (benefit)	37,514	(74,984)	4,208
Total income tax expense	179,775	128,793	130,183
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Federal statutory tax	167,181	118,412	132,482
Tax exempt revenue	(6,084)	(7,035)	(12,227)
Effect of state income taxes, net of federal benefit	22,489	14,251	12,715
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments	(8,801)	(6,994)	(5,127)
Other, net	4,990	10,159	2,340
Total income tax expense	$ 179,775	$ 128,793	$ 130,183
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory tax (in thousandths)	21.00%	21.00%	21.00%
Tax exempt revenue (in thousandths)	(0.70%)	(1.20%)	(1.90%)
Effect of state income taxes, net of federal benefit (in thousandths)	2.80%	2.50%	2.00%
Utilization of tax credits, net of proportional amortization of low-income housing limited partnership investments (in thousandths)	(1.10%)	(1.20%)	(0.80%)
Other, net (in thousandths)	0.60%	1.70%	0.30%
Total (in thousandths)	22.60%	22.80%	20.60%
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1	$ 22,902	$ 20,465	$ 18,869
Additions for tax for current year positions	3,961	6,384	5,649
Settlements during the period	(1,754)	0	0
Lapses of applicable statute of limitations	(4,017)	(3,947)	(4,053)
Balance as of December 31	21,092	22,902	20,465
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	16,400
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	2,300	2,400	$ 2,200
Unrecognized Tax Benefits, Penalties and Interest Accrued	$ 6,400	$ 5,900
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