Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 244,913	$ 195,890
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	14,814	14,352
Provision for credit losses	(32,288)	(22,140)
Gain on other real estate and foreclosed assets	(3,276)	(627)
Loss (gain) on sale of securities	87	(333)
Deferred tax expense	11,634	2,158
Increase in cash surrender value of life insurance contracts	(920)	(15,353)
Impairment of or loss on disposal of assets	539	15,274
Loss on extinguishment of debt		4,165
Net decrease in loans held for sale	43,329	45,414
Net amortization of securities premium/discount	21,311	26,211
Amortization of intangible assets	7,334	8,664
Stock-based compensation expense	11,379	11,646
Net change in derivative collateral liability	96,591	44,441
Decrease in interest payable and other liabilities	(19,009)	(6,229)
Decrease in other assets	108,679	45,301
Other, net	(18,286)	(1,271)
Net cash provided by operating activities	486,831	367,563
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from the sale of available for sale securities	73,219	198,681
Proceeds from maturities of securities available for sale	295,121	593,760
Purchases of securities available for sale	(383,398)	(2,235,723)
Proceeds from maturities of securities held to maturity	77,794	77,197
Purchases of securities held to maturity	(708,439)	(59,362)
Proceeds received upon termination of fair value hedge instruments	49,167
Net (increase) decrease in short-term investments	2,959,439	(869,999)
Net redemptions of Federal Home Loan Bank stock	37,423
Proceeds from sales of loans and leases	26,619	12,312
Net (increase) decrease in loans	(808,525)	670,795
Purchase of life insurance contracts	(65,000)	(75,000)
Proceeds from the surrender of life insurance contracts		44,045
Purchases of property and equipment	(18,212)	(7,636)
Proceeds from sales of other real estate	9,378	5,504
Other, net	4,277	6,549
Net cash provided by (used in) investing activities	1,548,863	(1,638,877)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in deposits	(599,465)	1,575,231
Net decrease in short-term borrowings	(1,035,050)	(151,005)
Proceeds from the issuance of long-term debt		22,388
Repayments of long-term debt	(480)	(153,287)
Dividends paid	(47,365)	(48,044)
Payroll tax remitted on net share settlement of equity awards	(1,799)	(1,082)
Proceeds from exercise of stock options	227	439
Proceeds from dividend reinvestment and stock purchase plans	1,800	1,962
Repurchase of common stock	(56,489)
Net cash provided by (used in) financing activities	(1,738,621)	1,246,602
NET INCREASE (DECREASE) IN CASH AND DUE FROM BANKS	297,073	(24,712)
CASH AND DUE FROM BANKS, BEGINNING	401,201	526,306
CASH AND DUE FROM BANKS, ENDING	698,274	501,594
SUPPLEMENTAL INFORMATION FOR NON-CASH INVESTING AND FINANCING ACTIVITIES
Assets acquired in settlement of loans	$ 118	$ 2,578