CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income	$ 30,852	$ 283,743	$ 339,889
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	13,845	14,752	15,977
Provision for credit losses	10,129	4,832	(70,876)
Share-based compensation expense	19,390	18,925	13,264
Loss on sale and disposal of premises and equipment	619	89	234
(Gain) on sale of or write down of other real estate owned	(82)	0	0
Net amortization on securities	12,827	18,618	24,468
Net (accretion) of discounts/premiums for acquired loans and deferred loan fees/costs	(15,298)	(27,310)	(41,162)
Loss (gain) on sale of investment securities available-for-sale	253,927	(1,710)	(16,906)
(Gain) loss on debt extinguishment	(793)	0	180
Originations of loans held for sale, net of principal payments received	(1,386)	(61,237)	(51,098)
Proceeds from the sales of loans held for sale	2,085	73,300	44,734
Gain on sales of loans	(415)	(3,238)	(4,428)
Deferred income tax expense	3,962	5,899	28,807
Net change in accrued expenses and other liabilities	21,204	6,512	(29,038)
Income from bank owned life insurance, net	(11,440)	(10,658)	(9,000)
Amortization of intangible assets	12,303	13,983	15,936
Net change in accrued interest receivable and other assets	(100,749)	74,532	59,234
Net cash provided by operating activities	250,980	411,032	320,215
Cash flows from investing activities:
Net decrease in interest-bearing time deposits with financial institutions	739	482	629
Proceeds from sales of other real estate owned	3,835	0	0
Loan (originations) and payments, net	1,298,976	(431,181)	(1,022,505)
Proceeds from sales of loans previously classified as loans held for investment	116,932	5,800	1,530
Purchase of loans held for investment	0	(797)	0
Purchase of securities held-to-maturity	(23,267)	0	(48,695)
Proceeds from prepayments and maturities of securities held-to-maturity	47,413	20,115	10,334
Purchase of securities available-for-sale	(761,586)	(986,997)	(2,231,699)
Proceeds from prepayments and maturities of securities available-for-sale	253,185	326,980	563,061
Proceeds from sales of securities available-for-sale	1,568,604	936,413	901,137
Proceeds from the sales of premises and equipment	12	0	55
Proceeds from surrender of bank owned life insurance	272	0	1,809
Purchase of bank owned life insurance	0	0	(150,000)
Purchases of premises and equipment	(6,609)	(7,476)	(9,290)
Net change in FHLB, FRB, and other stock	7,926	(10,571)	(62)
Funding of Community Reinvestment Act (“CRA”) investments, net	(34,534)	(12,861)	(24,001)
Net cash provided by (used in) investing activities	2,471,898	(160,093)	(2,007,697)
Cash flows from financing activities:
Net change in deposit accounts	(2,356,775)	236,812	901,412
Net change in short-term borrowings	(200,000)	(358,000)	548,000
Proceeds from long-term borrowings	0	800,000	0
Repayment of long-term borrowings	(199,207)	0	(21,503)
Redemption of subordinated debentures	0	0	(171,153)
Cash dividends paid	(126,265)	(125,160)	(121,887)
Repurchase and retirement of common stock	0	0	(18,067)
Proceeds from exercise of stock options	966	873	1,001
Restricted stock surrendered and canceled	(6,373)	(8,918)	(6,384)
Net cash (used in) provided by financing activities	(2,887,654)	545,607	1,111,419
Net change in cash and cash equivalents	(164,776)	796,546	(576,063)
Cash and cash equivalents, beginning of year	1,101,249	304,703	880,766
Cash and cash equivalents, end of year	936,473	1,101,249	304,703
Supplemental cash flow disclosures:
Interest paid	258,938	59,149	38,761
Income taxes paid	53,135	75,294	86,535
Noncash investing activities during the period:
Transfers from loans held for investment to loans held for sale	117,441	6,399	1,006
Loans held for sale transfer to loans held for investment	2,868	0	0
Other real estate owned transferred from loans held for investment	7,590	0	0
Transfers of investment securities from available-for-sale to held-to-maturity	360,347	1,019,472	319,924
Transfer of CRA investment securities from FHLB, FRB, and other stock to other assets	12,601	0	0
Transfer of investment securities from FHLB, FRB, and other to held-to-maturity	0	7,000	0
Recognition of operating lease right-of-use assets	(7,360)	(1,635)	(5,003)
Recognition of operating lease liabilities	$ 7,437	$ 1,635	$ 5,003