Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
OPERATING ACTIVITIES
Net income	$ 353,639	$ 355,497
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	52,949	23,714
Deferred tax expense (benefit)	16,227	43,939
Net change in current taxes	(38,878)	(33,433)
Depreciation	81,169	77,024
Net (decrease) increase in accrued interest payable	(7,620)	14,147
Net (increase) decrease in income earned not collected	(28,025)	(3,567)
Contribution to pension plans	(100,000)	(3,500)
Contribution to pension plans	(54,972)	(6,855)
Marketable equity securities gain (loss), net	(10,461)	(13,505)
Origination of loans held for sale	(775,900)	(518,894)
Origination of loans held for sale	743,508	490,261
Gain on sale of loans held for sale	(25,728)	(10,607)
Net writedowns/losses on other real estate	2,360	1,924
Net accretion of premiums and discounts	4,599	(24,769)
Amortization of intangible assets	18,589	17,934
Net change in mortgage servicing rights	(1,332)	(3,770)
Net change in other assets	(6,394)	2,536
Net change in other liabilities	(7,472)	(8,916)
Net cash provided by operating activities	216,258	399,160
INVESTING ACTIVITIES
Net increase in loans outstanding	(3,876,578)	(629,705)
Purchases of investment securities available for sale	(7,608,380)	(3,706,949)
Purchases of investment securities held to maturity	(856,047)	(223,353)
Purchases of marketable equity securities	(333,126)	(23,238)
Proceeds from maturities/calls of investment securities held to maturity	134,736	305,479
Proceeds from maturities/calls of investment securities available for sale	1,909,462	1,690,277
Proceeds from sales of investment securities available for sale	3,889,386	1,746,099
Proceeds from sales of marketable equity securities	332,762	12,739
Net increase in overnight investments	(1,994,972)	(150,006)
Proceeds from sales of portfolio loans	0	24,247
Repayment of FDIC Shared-Loss Payable	(99,468)	0
Proceeds from sales of other real estate	19,683	18,892
Proceeds from sales of premises and equipment	46	128
Purchases of premises and equipment	(98,490)	(89,219)
Business acquisitions, net of cash acquired	(59,999)	(73,792)
Net cash used in investing activities	(8,640,985)	(1,098,401)
FINANCING ACTIVITIES
Net decrease in time deposits	(759,491)	376,596
Net increase in demand and other interest-bearing deposits	8,556,808	701,426
Net decrease in short-term borrowings	(44,344)	(138,741)
Repayments of Other Long-term Debt	(82,747)	(43,545)
Origination of long-term obligations	400,000	100,000
Proceeds from Debt, Net of Issuance Costs	345,849	0
Proceeds from issuance of preferred stock, net of issuance costs	339,937
Proceeds from Issuance of Preferred Stock and Preference Stock	345,000	0
Repurchase of common stock	(333,755)	(321,263)
Cash dividends paid	(21,830)	(13,739)
Net cash (used in) provided by financing activities	8,400,427	660,734
Change in cash and due from banks	(24,300)	(38,507)
Cash and due from banks at beginning of period	376,719	327,440
Cash and due from banks at end of period	352,419	288,933
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Transfers of loans to other real estate	10,295	13,242
Dividends declared but not paid	3,926	4,397
Net reclassification of portfolio loans (to) from loans held for sale	(3,464)	22,758
Transfers of premises and equipment to other real estate	8,133	2,184
Unsettled common stock repurchases	$ 0	$ 4,653