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 (loss)	$ 524,089	$ 463,215	$ (45,174)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	31,582	29,113	30,128
Provision for credit losses	(28,399)	(77,494)	602,904
(Gain) loss on other real estate and foreclosed assets	(4,382)	(2,280)	9,581
Deferred tax expense (benefit)	(22,166)	10,376	(20,716)
Increase in cash surrender value of life insurance contracts	(7,010)	(23,505)	(19,244)
Impairment of or loss on disposal of assets	259	14,354	3,159
Loss on extinguishment of debt		4,165
Loss (gain) on sale of securities available for sale	87	(333)	(488)
Net (increase) decrease in loans held for sale	61,031	41,157	(77,544)
Net amortization of securities premium/discount	35,490	50,311	43,226
Amortization of intangible assets	14,033	16,665	19,916
Stock-based compensation expense	23,489	22,442	21,107
Net change in derivative collateral liability	64,867	62,670	(80,290)
Increase in interest payable and other liabilities	6,838	20,869	4,687
(Increase) decrease in other assets	176,354	(21,050)	(111,094)
Other, net	(34,141)	(24,985)	(24,967)
Net cash provided by operating activities	842,021	585,690	355,191
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales of securities available for sale	73,219	198,681	211,919
Proceeds from maturities of securities available for sale	502,628	1,073,133	1,001,720
Purchases of securities available for sale	(635,593)	(2,527,272)	(2,371,954)
Proceeds from maturities of securities held to maturity	147,879	116,536	218,205
Purchases of securities held to maturity	(884,427)	(338,089)	(20,884)
Proceeds received upon termination of fair value hedge instruments	90,601
Net redemptions (purchases) of Federal Home Loan Bank stock	(12,095)	52,535	(12,868)
Net (increase) decrease in short-term investments	3,506,845	(2,496,849)	(1,223,557)
Proceeds from sales of loans and leases	30,652	22,485	328,958
Net (increase) decrease in loans	(2,088,836)	670,958	(1,296,136)
Purchases of life insurance contracts	(65,000)	(75,000)
Proceeds from surrender of life insurance contracts		44,045
Purchases of property and equipment	(29,145)	(23,541)	(37,869)
Proceeds from sales of other real estate and foreclosed assets	14,081	15,527	17,923
Other, net	11,549	42,267	7,071
Net cash provided by (used in) investing activities	662,358	(3,224,584)	(3,177,472)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in deposits	(1,395,548)	2,768,020	3,894,302
Net increase (decrease) in short-term borrowings	206,210	(2,452)	(1,047,359)
Repayments of long-term debt	(480)	(153,444)	(308)
Issuance of long-term debt, net of issuance costs	5,629	22,388	166,425
Dividends paid	(94,458)	(95,927)	(95,605)
Payroll tax remitted on net share settlement of equity awards	(7,386)	(7,364)	(4,530)
Cash received under accelerated share repurchase agreement			12,110
Other repurchases of common stock	(58,892)	(21,796)	(12,716)
Proceeds from exercise of stock options	227	492
Proceeds from dividend reinvestment and stock purchase plan	3,577	3,872	4,164
Net cash provided by (used in) financing activities	(1,341,121)	2,513,789	2,916,483
NET INCREASE (DECREASE) IN CASH AND DUE FROM BANKS	163,258	(125,105)	94,202
CASH AND DUE FROM BANKS, BEGINNING	401,201	526,306	432,104
CASH AND DUE FROM BANKS, ENDING	564,459	401,201	526,306
SUPPLEMENTAL INFORMATION
Income taxes paid	135,193	122,594	17,465
Interest paid	80,076	49,995	121,343
SUPPLEMENTAL INFORMATION FOR NON-CASH INVESTING AND FINANCING ACTIVITIES
Assets acquired in settlement of loans	$ 596	$ 2,806	$ 6,420