Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
OPERATING ACTIVITIES
Net income	$ 57,169	$ 111,359
Adjustments to reconcile net income to cash provided by operating activities:
Provision (credit) for loan and lease losses	28,355	11,750
Deferred tax expense (benefit)	(11,485)	(7,316)
Net change in current taxes	11,829	37,898
Depreciation	26,879	28,195
Net (decrease) increase in accrued interest payable	(4,624)	3,457
Net (increase) decrease in income earned not collected	(1,914)	(3,909)
Contribution to pension plans	(100,000)	0
Contribution to pension plans	(19,795)	0
Marketable equity securities gain (loss), net	51,408	(11,328)
Origination of loans held for sale	(205,986)	(128,949)
Origination of loans held for sale	201,886	123,047
Gain on sale of loans held for sale	(5,682)	(2,181)
Net writedowns/losses on other real estate	1,419	427
Net accretion of premiums and discounts	4,674	(7,099)
Amortization of intangible assets	6,160	5,943
Net change in mortgage servicing rights	1,384	(698)
Net change in other assets	4,067	31,422
Net change in other liabilities	(28,135)	(51,985)
Net cash provided by operating activities	17,609	140,033
INVESTING ACTIVITIES
Net increase in loans outstanding	(202,667)	68,052
Purchases of investment securities available for sale	(4,305,818)	(593,952)
Purchases of investment securities held to maturity	(724,412)	(116,028)
Purchases of marketable equity securities	(287,014)	(6,076)
Proceeds from maturities/calls of investment securities held to maturity	14,166	88,400
Proceeds from maturities/calls of investment securities available for sale	572,937	587,023
Proceeds from sales of investment securities available for sale	3,156,988	0
Proceeds from sales of marketable equity securities	2,438	119
Net decrease (increase) in overnight investments	454,455	(589,119)
Repayment of FDIC Shared-Loss Payable	(99,468)	0
Proceeds from sales of other real estate	5,265	7,430
Proceeds from sales of premises and equipment	0	54
Purchases of premises and equipment	(26,930)	(23,875)
Business acquisitions, net of cash acquired	(1,235)	0
Net cash used in investing activities	(1,441,295)	(577,972)
FINANCING ACTIVITIES
Net decrease in time deposits	(310,224)	138,640
Net increase in demand and other interest-bearing deposits	1,017,371	387,319
Net decrease in short-term borrowings	(92,871)	(35,428)
Repayments of Other Long-term Debt	(38,583)	(8,688)
Origination of long-term obligations	400,000	0
Proceeds from Debt, Net of Issuance Costs	345,886	0
Proceeds from issuance of preferred stock, net of issuance costs	339,958
Proceeds from Issuance of Preferred Stock and Preference Stock	345,000	0
Repurchase of common stock	(156,094)	(98,077)
Cash dividends paid	(4,256)	(4,668)
Net cash (used in) provided by financing activities	1,501,187	379,098
Change in cash and due from banks	77,501	(58,841)
Cash and due from banks at beginning of period	376,719	327,440
Cash and due from banks at end of period	454,220	268,599
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Dividends declared but not paid	4,141	4,575
Net reclassification of portfolio loans from loans held for sale	(1,304)	(605)
Transfers of premises and equipment to other real estate	4,560	2,613
Property, Plant And Equipment Owned, Transfer To Real Estate Owned	1,427	520
Unsettled common stock repurchases	3,610	2,679
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 1,191	$ 0