CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net income	$ 265,685	$ 265,735	$ 185,754
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	1,392	(39,000)	121,718
Depreciation, amortization and accretion, net	56,747	51,844	63,071
Deferred income tax provision (benefits)	22,138	14,120	(19,396)
Stock-based compensation	10,298	13,106	10,028
Other losses (gains)	2,658	(1,437)	(4)
Originations of loans held for sale	(15,694)	(87,336)	(327,076)
Proceeds from sales of loans held for sale	15,234	100,499	326,785
Net losses (gains) on sales of loans originated for investment and held for sale	164	(2,706)	(18,995)
Net (gains) losses on investment securities		(102)	114
Change in assets and liabilities:
Net decrease (increase) in other assets	18,469	(8,211)	(17,880)
Net increase (decrease) in other liabilities	53,523	110,613	(114,613)
Net cash provided by operating activities	430,614	417,125	209,506
Available-for-sale securities:
Proceeds from maturities and principal repayments	873,747	1,814,514	1,474,587
Proceeds from calls and sales	1,080	11,115	644,983
Purchases	(938,268)	(4,428,656)	(4,045,871)
Held-to-maturity securities:
Proceeds from maturities and principal repayments	350,593
Proceeds from calls	585
Purchases	(79,470)
Other investments:
Proceeds from sales	7,967	28,483	34,822
Purchases	(31,087)	(80,464)	(77,927)
Loans:
Net (increase) decrease in loans and leases resulting from originations and principal repayments	(914,318)	594,642	(217,530)
Proceeds from sales of loans originated for investment	288	2,200	153,647
Purchases of loans	(235,884)	(309,760)	(41,146)
Proceeds from bank-owned life insurance		7,903	3,089
Purchases of premises, equipment and software	(13,295)	(20,458)	(33,390)
Proceeds from sales of premises and equipment	17,304	4,021
Proceeds from sales of other real estate owned	337	141	787
Other	(4,679)		186
Net cash used in investing activities	(965,100)	(2,376,319)	(2,103,763)
Cash flows from financing activities
Net (decrease) increase in deposits	(127,117)	2,588,423	2,782,729
Proceeds (repayments) of short-term borrowings	75,000		(400,000)
Repayment of long-term borrowings		(200,010)	(9)
Dividends paid	(132,588)	(134,133)	(135,099)
Stock tendered for payment of withholding taxes	(3,555)	(3,108)	(1,749)
Proceeds from employee stock purchase plan	379	547	312
Common stock repurchased	(9,478)	(75,000)	(5,000)
Net cash provided by (used in) financing activities	(197,359)	2,176,719	2,241,184
Net (decrease) increase in cash and cash equivalents	(731,845)	217,525	346,927
Cash and cash equivalents at beginning of year	1,258,469	1,040,944	694,017
Cash and cash equivalents at end of year	526,624	1,258,469	1,040,944
Supplemental disclosures
Interest paid	44,325	23,001	52,865
Income taxes paid, net of income tax refunds	24,692	55,354	53,272
Noncash investing and financing activities:
Transfers from loans and leases and other assets to other real estate owned	226	316	437
Operating lease right-of-use assets obtained in exchange for new lease obligations	4,676	31,792	3,796
Transfers (to) from loans and leases (from) to loans held for sale		1,616	145,036
Transfers to loans and leases from loans held for sale	(546)
Obligation to fund low-income housing partnerships	7,569	$ 35,721	$ 13,767
Transfers of securities from available-for-sale to held-to-maturity	$ 4,550,748