CONSOLIDATED STATEMENTS OF CASH FLOW - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Cash Flows [Abstract]
Net income	$ 124,934	$ 120,532	$ 118,557
Adjustments to reconcile net income to net cash provided by operating activities:
Provision (recovery of provision) for credit losses	5,866	13,245	(4,303)
Depreciation of premises and equipment	4,452	4,596	5,093
Depreciation - leased equipment	7,093	10,023	13,694
Stock-based compensation	4,891	3,587	4,214
Amortization of investment securities premiums and accretion of discounts, net	3,939	3,951	6,684
Amortization of mortgage servicing rights	845	1,287	2,117
Mortgage servicing rights recoveries	0	0	(812)
Amortization of right of use assets	3,073	3,181	3,095
Deferred income taxes	(9,462)	(9,461)	15,396
Losses on investment securities available-for-sale	2,926	184	680
Originations of loans held for sale, net of principal collected	(43,665)	(86,185)	(261,558)
Proceeds from the sales of loans held for sale	47,060	97,166	268,226
Net gains on sale of loans held for sale	(923)	(1,611)	(7,067)
Net gains on sale of other real estate and repossessions	(123)	(410)	(672)
Change in interest receivable	(5,485)	(6,987)	2,482
Change in interest payable	23,521	4,115	(2,111)
Change in other assets	4,089	413	17,757
Change in other liabilities	17,864	21,910	(14,990)
Other	(2,959)	(4,006)	279
Net change in operating activities	187,936	175,530	166,761
Investing activities:
Proceeds from sales of investment securities available-for-sale	102,437	23,795	99,208
Proceeds from maturities and paydowns of investment securities available-for-sale	145,006	206,426	336,364
Purchases of investment securities available-for-sale	(47,494)	(327,496)	(1,145,697)
Net change in partnership investments	(51,121)	(18,292)	(24,897)
Net change in other investments	218	1,896	240
Loans sold or participated to others	49,603	57,473	54,623
Proceeds from principal payments on direct finance leases	71,044	58,654	40,751
Net change in loans and leases	(628,268)	(784,355)	36,414
Net change in equipment owned under operating leases	4,241	6,710	2,913
Purchases of premises and equipment	(5,980)	(2,380)	(2,886)
Proceeds from disposal of premises and equipment	142	49	129
Purchases of bank owned life insurance policies	0	(10,000)	0
Proceeds from sales of other real estate and repossessions	1,886	2,648	4,279
Net change in investing activities	(358,286)	(784,872)	(598,559)
Financing activities:
Net change in demand deposits and savings accounts	(487,911)	(7,122)	1,016,257
Net change in time deposits	598,227	256,322	(283,220)
Net change in short-term borrowings	96,830	15,502	49,386
Payments on long-term debt	(3,450)	(25,530)	(13,460)
Stock issued under stock purchase plans	78	252	90
Acquisition of treasury stock	(12,469)	(6,836)	(33,136)
Net contributions from (distributions to) noncontrolling interests	18,990	6,466	9,361
Cash dividends paid on common stock	(33,074)	(32,102)	(31,340)
Net change in financing activities	177,221	206,952	713,938
Net change in cash and cash equivalents	6,871	(402,390)	282,140
Cash and cash equivalents, beginning of year	122,797	525,187	243,047
Cash and cash equivalents, end of year	$ 129,668	$ 122,797	$ 525,187