Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
OPERATING ACTIVITIES
Net income	$ 424,177	$ 353,639
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	(31,697)	52,949
Deferred tax expense (benefit)	9,266	16,227
Net change in current taxes	(774,212)	(38,878)
Depreciation and amortization	80,293	81,169
Net (decrease) increase in accrued interest payable	(2,855)	(7,620)
Net decrease (increase) in income earned not collected	12,783	(28,025)
Contribution to pension plans	0	(100,000)
Realized gains on investment securities available for sale, net	(33,119)	(54,972)
Marketable equity securities gains, net	(31,015)	(10,461)
Origination of loans held for sale	(911,995)	(775,900)
Proceeds from Sale of Loans Held-for-sale	808,172	743,508
Gain on sale of loans	(26,789)	(25,728)
Net (gains) losses on other real estate owned	(2,971)	2,360
Net accretion of premiums and discounts	5,017	4,599
Amortization of intangible assets	16,408	18,589
Origination of mortgage servicing rights, net of change in valuation allowance	(9,775)	(1,332)
Net change in other assets	14,233	(6,394)
Net change in other liabilities	(7,692)	(7,472)
Net cash provided by operating activities	(461,771)	216,258
INVESTING ACTIVITIES
Net increase in loans outstanding	325,209	(3,876,578)
Purchases of investment securities available for sale	(3,620,680)	(7,608,380)
Purchases of investment securities held to maturity	(1,199,419)	(856,047)
Purchases of marketable equity securities	(1,563)	(333,126)
Proceeds from maturities/calls of investment securities held to maturity	605,664	134,736
Proceeds from maturities/calls of investment securities available for sale	1,968,339	1,909,462
Proceeds from sales of investment securities available for sale	1,366,909	3,889,386
Proceeds from sales of marketable equity securities	1,111	332,762
Net increase in overnight investments	(5,527,727)	(1,994,972)
Cash paid to FDIC for settlement of shared-loss agreement	(16,103)	(99,468)
Proceeds from sales of other real estate	29,666	19,683
Proceeds from sales of premises and equipment	1,194	46
Purchases of premises and equipment	(72,463)	(98,490)
Business acquisitions, net of cash acquired	0	(59,999)
Other investing activities	(18,940)	0
Net cash used in investing activities	(6,158,803)	(8,640,985)
FINANCING ACTIVITIES
Net decrease in time deposits	(314,004)	(759,491)
Net increase in demand and other interest-bearing deposits	6,949,598	8,556,808
Net decrease in short-term borrowings	22,088	(44,344)
Repayments of Other Long-term Debt	(29,343)	(82,747)
Origination of long-term obligations	0	745,849
Net proceeds from preferred stock issuance	0	339,937
Repurchase of common stock	0	(333,755)
Cash dividends paid	(32,363)	(21,830)
Net cash (used in) provided by financing activities	6,595,976	8,400,427
Change in cash and due from banks	(24,598)	(24,300)
Cash and due from banks at beginning of period	362,048	376,719
Cash and due from banks at end of period	337,450	352,419
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Interest	48,926	85,344
Income taxes	871,327	117,716
Transfers of loans to other real estate	7,861	10,295
Dividends declared but not paid	0	3,926
Unsettled call of investment securities	15,000	0
Loans held for sale exchanged for investment securities	177,301	0
Reclassification of portfolio loans to loans held for sale	22,655	(3,464)
Transfers of premises and equipment to other real estate	$ 8,593	$ 8,133