Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities
Net Income	$ 111,490	$ 167,770
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Provision for Credit Losses	102,600	11,250
Depreciation and Amortization	14,929	12,685
Amortization of Deferred Loan and Lease Fees	(1,640)	(85)
Amortization and Accretion of Premiums/Discounts on Investment Securities, Net	19,043	15,102
Amortization of Operating Lease Right-of-Use Assets	9,192	9,495
Share-Based Compensation	5,347	6,662
Benefit Plan Contributions	(1,071)	(1,472)
Deferred Income Taxes	(31,725)	(5,805)
Gains on Sale of Premises and Equipment	(1,850)	(558)
Net Gains on Sales of Loans and Leases	(9,779)	(3,705)
Net Losses (Gains) on Sales of Investment Securities	(11,125)	3,080
Proceeds from Sales of Loans Held for Sale	333,770	299,062
Originations of Loans Held for Sale	(316,203)	(322,721)
Net Tax Benefits from Share-Based Compensation	469	693
Net Change in Other Assets and Other Liabilities	(135,753)	(38,710)
Net Cash Provided by Operating Activities	87,694	152,743
Investment Securities Available-for-Sale:
Proceeds from Sales, Prepayments and Maturities	733,619	1,656,241
Purchases	(1,238,926)	(1,203,633)
Investment Securities Held-to-Maturity:
Proceeds from Prepayments and Maturities	1,000,743	518,822
Purchases	(1,170,928)	(1,006,455)
Net Change in Loans and Leases	(782,613)	(441,007)
Purchases of Premises and Equipment	(25,693)	(40,381)
Proceeds from Sale of Premises and Equipment	1,981	639
Net Cash Used in Investing Activities	(1,481,817)	(515,774)
Financing Activities
Net Change in Deposits	1,954,401	313,510
Net Change in Short-Term Borrowings	(2,200)	99,804
Proceeds from Long-Term Debt	50,000	0
Repayments of Long-Term Debt	(75,063)	(25,058)
Proceeds from Issuance of Common Stock	7,684	6,103
Repurchase of Common Stock	(17,897)	(107,875)
Cash Dividends Paid	(80,536)	(78,538)
Net Cash Provided by Financing Activities	1,836,389	207,946
Net Change in Cash and Cash Equivalents	442,266	(155,085)
Cash and Cash Equivalents at Beginning of Period	558,658	525,969
Cash and Cash Equivalents at End of Period	1,000,924	370,884
Supplemental Information
Cash Paid for Interest	42,712	68,284
Cash Paid for Income Taxes	46,949	43,905
Non-Cash Investing and Financing Activities:
Initial Recognition of Operating Lease Right-of-Use Assets	0	106,514
Initial Recognition of Operating Lease Liabilities	0	113,394
Transfer from Investment Securities Held-To-Maturity to Investment Securities Available-For-Sale	0	1,014,859
Transfer from Loans to Foreclosed Real Estate	$ 0	$ 2,070