CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities:
Net income	$ 188,081	$ 189,694	$ 164,676
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	14,411	15,592	15,963
Amortization of intangible assets	15,214	14,051	14,297
Net accretion on securities, loans and borrowings	(18,738)	(22,501)	(11,353)
Stock-based compensation	7,738	6,334	6,419
Provision for credit losses	14,773	(8,839)	14,212
Provision (benefit) for deferred income taxes	1,309	7,989	(2,336)
Amortization of mortgage servicing rights	801	519	379
Unrealized loss (gain) on equity securities	44	(17)	6
Gain on debt extinguishment	0	0	(421)
Income from bank-owned life insurance policies	(2,147)	(2,012)	(1,915)
Net gain on sale of assets	(655)	(328)	(3,505)
Change in other assets and liabilities	(6,231)	2,064	(16,939)
Net cash provided by operating activities	214,600	202,546	179,483
Investing activities:
Proceeds from maturities, calls and paydowns of available-for-sale investment securities	262,256	423,738	885,549
Proceeds from maturities and redemptions of equity and other securities	4,683	2,946	516
Purchases of available-for-sale investment securities	(1,355,475)	(1,963,884)	(1,114,914)
Purchases of equity and other securities	(35,303)	(353)	(3,234)
Net (increase) decrease in loans	(1,003,741)	49,929	(185,131)
Cash (paid) received for acquisition, net of cash acquired of $84,988, $541, and $55,973, respectively	(668)	(29,329)	34,360
Proceeds from sales of premises and equipment, net	2,432	201	389
Purchases of premises and equipment, net	(12,922)	(13,377)	(14,784)
Real estate limited partnership investments	(247)	(646)	(1,471)
Net cash used in investing activities	(2,138,985)	(1,530,775)	(398,720)
Financing activities:
Net (decrease) increase in deposits	(421,155)	1,686,194	1,713,733
Net increase (decrease) in overnight borrowings	768,400	0	(8,300)
Net increase in securities sold under agreement to repurchase, short-term	21,932	40,711	42,300
Payments on other Federal Home Loan Bank borrowings	(95)	(4,769)	(3,092)
Payments on subordinated debt held by unconsolidated subsidiary trusts	0	(77,320)	(2,062)
Payments on subordinated notes payable	0	0	(10,000)
Proceeds from the issuance of common stock	1,184	9,821	15,792
Purchases of treasury stock	(16,614)	(5,106)	(271)
Proceeds from the sale of treasury stock	0	0	85
Increase in deferred compensation agreements	236	252	271
Cash dividends paid	(93,387)	(91,051)	(87,131)
Withholding taxes paid on share-based compensation	(1,284)	(1,244)	(1,313)
Net cash provided by financing activities	259,217	1,557,488	1,660,012
Change in cash and cash equivalents	(1,665,168)	229,259	1,440,775
Cash and cash equivalents at beginning of year	1,875,064	1,645,805	205,030
Cash and cash equivalents at end of year	209,896	1,875,064	1,645,805
Supplemental disclosures of cash flow information:
Cash paid for interest	23,402	13,752	21,169
Cash paid for income taxes	57,131	41,531	39,578
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	23,762	23,235	22,695
Transfers from loans to other real estate	543	520	1,291
Transfers from premises and equipment, net to other assets	5,795	0	0
Acquisitions:
Common stock issued	0	0	76,942
Fair value of assets acquired, excluding acquired cash and intangibles	490,467	1,339	547,654
Fair value of liabilities assumed	$ 543,452	$ 1,164	$ 529,177