CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities:
Net income	$ 131,924	$ 188,081	$ 189,694
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	12,991	14,411	15,592
Amortization of intangible assets	14,511	15,214	14,051
Net amortization (accretion) on securities, loans and borrowings	5,838	(18,738)	(22,501)
Stock-based compensation	9,269	7,738	6,334
Gain on debt extinguishment	(242)	0	0
Provision for credit losses	11,203	14,773	(8,839)
Provision for deferred income taxes	(7,503)	1,309	7,989
Amortization of mortgage servicing rights	849	801	519
Loss on sales of investment securities	52,329	0	0
Unrealized loss (gain) on equity securities	47	44	(17)
Income from bank-owned life insurance policies	(2,412)	(2,147)	(2,012)
Net gain on sale of assets	(1,490)	(655)	(328)
Change in other assets and liabilities	1,106	(6,231)	2,064
Net cash provided by operating activities	228,420	214,600	202,546
Investing activities:
Proceeds from maturities, calls and paydowns of available-for-sale investment securities	597,823	262,256	423,738
Proceeds from maturities, calls and paydowns of held-to-maturity investment securities	208	0	0
Proceeds from maturities and redemptions of equity and other investment securities, net	14,945	4,683	2,946
Proceeds from sales of available-for-sale investment securities	733,789	0	0
Purchases of available-for-sale investment securities	0	(1,355,475)	(1,963,884)
Purchases of held-to-maturity investment securities	(63,284)	0	0
Purchases of equity and other securities	(4,796)	(35,303)	(353)
Net (increase) decrease in loans	(923,280)	(1,003,741)	49,929
Cash paid for acquisitions, net of cash acquired of $0, $84,988, and $541, respectively	(8,517)	(668)	(29,329)
Proceeds from sales of premises, equipment and other assets	7,473	2,432	201
Purchases of premises and equipment	(18,585)	(12,922)	(13,377)
Real estate limited partnership investments	0	(247)	(646)
Net cash provided by (used in) investing activities	335,776	(2,138,985)	(1,530,775)
Financing activities:
Net (decrease) increase in deposits	(84,187)	(421,155)	1,686,194
Net (decrease) increase in overnight borrowings	(715,400)	768,400	0
Net (decrease) increase in securities sold under agreement to repurchase, short-term	(42,058)	21,932	40,711
Proceeds from other Federal Home Loan Bank borrowings	400,000	0	0
Payments on and maturities of other Federal Home Loan Bank borrowings	(11,971)	(95)	(4,769)
Payments of contingent consideration for acquisitions	(1,214)	0	0
Payments on subordinated debt held by unconsolidated subsidiary trusts	0	0	(77,320)
Redemption of subordinated notes payable	(3,000)	0	0
Proceeds from the issuance of common stock	1,015	1,184	9,821
Purchases of treasury stock	(30,233)	(16,614)	(5,106)
Increase in deferred compensation agreements	217	236	252
Cash dividends paid	(95,102)	(93,387)	(91,051)
Withholding taxes paid on share-based compensation	(1,197)	(1,284)	(1,244)
Net cash (used in) provided by financing activities	(583,130)	259,217	1,557,488
Change in cash and cash equivalents	(18,934)	(1,665,168)	229,259
Cash and cash equivalents at beginning of year	209,896	1,875,064	1,645,805
Cash and cash equivalents at end of year	190,962	209,896	1,875,064
Supplemental disclosures of cash flow information:
Cash paid for interest	100,040	23,402	13,752
Cash paid for income taxes	41,661	57,131	41,531
Supplemental disclosures of noncash financing and investing activities:
Dividends declared and unpaid	24,168	23,762	23,235
Transfers from loans to other real estate	1,051	543	520
Transfers from premises and equipment, net to other assets	2,899	5,795	0
Acquisitions:
Fair value of assets acquired, excluding acquired cash and intangibles	243	490,637	1,339
Fair value of liabilities assumed	18	543,541	1,164
Contingent consideration in exchange for acquired assets	$ 1,450	$ 0	$ 2,900