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	$ 234,983	$ 265,685	$ 265,735
Adjustments to reconcile net income to net cash provided by operating activities:
Provision (benefit) for credit losses	26,630	1,392	(39,000)
Depreciation, amortization and accretion, net	42,767	56,747	51,844
Deferred income tax (benefit) provision	(13,656)	22,138	14,120
Stock-based compensation	9,609	10,298	13,106
Other (gains) losses	(5,834)	2,822	(4,143)
Originations of loans held for sale	(21,324)	(15,694)	(87,336)
Proceeds from sales of loans held for sale	22,240	15,234	100,499
Net gains on investment securities	(792)		(102)
Change in assets and liabilities:
Net (increase) decrease in other assets	(40,156)	18,469	(8,211)
Net increase in other liabilities	559	53,523	110,613
Net cash provided by operating activities	255,026	430,614	417,125
Available-for-sale securities:
Proceeds from maturities and principal repayments	431,535	873,747	1,814,514
Proceeds from calls and sales	510,837	1,080	11,115
Purchases		(938,268)	(4,428,656)
Held-to-maturity securities:
Proceeds from maturities and principal repayments	311,195	350,593
Proceeds from calls	8,290	585
Purchases		(79,470)
Other investments:
Proceeds from sales	131,288	7,967	28,483
Purchases	(133,212)	(31,087)	(80,464)
Loans:
Net increase in loans and leases resulting from originations and principal repayments	(177,923)	(914,318)	594,642
Proceeds from sales of loans originated for investment		288	2,200
Purchases of loans	(57,879)	(235,884)	(309,760)
Proceeds from bank-owned life insurance	8,486		7,903
Purchases of premises, equipment and software	(15,988)	(13,295)	(20,458)
Proceeds from sales of premises and equipment	8,509	17,304	4,021
Other	34	(4,342)	141
Net cash provided by (used in) investing activities	1,025,172	(965,100)	(2,376,319)
Cash flows from financing activities
Net (decrease) increase in deposits	(356,372)	(127,117)	2,588,423
Net (decrease) increase in short-term borrowings	(75,000)	75,000
Proceeds from long-term borrowings	500,000
Repayment of long-term borrowings			(200,010)
Dividends paid	(132,646)	(132,588)	(134,133)
Stock tendered for payment of withholding taxes	(3,215)	(3,555)	(3,108)
Proceeds from employee stock purchase plan	308	379	547
Common stock repurchased		(9,478)	(75,000)
Net cash provided by financing activities	(66,925)	(197,359)	2,176,719
Net increase (decrease) in cash and cash equivalents	1,213,273	(731,845)	217,525
Cash and cash equivalents at beginning of year	526,624	1,258,469	1,040,944
Cash and cash equivalents at end of year	1,739,897	526,624	1,258,469
Supplemental disclosures
Interest paid	262,186	44,325	23,001
Income taxes paid, net of income tax refunds	54,021	24,692	55,354
Noncash investing and financing activities:
Transfers from loans and leases and other assets to other real estate owned		226	316
Operating lease right-of-use assets obtained in exchange for new lease obligations	4,775	4,676	31,792
Transfers to loans and leases from loans held for sale		546
Transfers to loans held for sale from loans and leases	1,133		1,616
Obligation to fund low-income housing partnerships	$ 63,086	7,569	$ 35,721
Transfers of securities from available-for-sale to held-to-maturity		$ 4,550,748