Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating Activities
Net Income	$ 95,838	$ 94,455
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Provision for Credit Losses	8,650	(1,000)
Depreciation and Amortization	6,565	6,596
Amortization of Deferred Loan and Lease Fees	(535)	(773)
Amortization and Accretion of Premiums/Discounts on Investment Securities, Net	20,027	22,277
Share-Based Compensation	3,726	3,314
Benefit Plan Contributions	(741)	(655)
Deferred Income Taxes	3,635	(5,354)
Net Gains on Sales of Loans and Leases	(3,971)	(4,095)
Net Gains on Sales of Investment Securities	(11,613)	(10,868)
Proceeds from Sales of Loans Held for Sale	146,478	67,983
Originations of Loans Held for Sale	(150,414)	(84,660)
Net Tax Benefit from Share-Based Compensation	2,077	0
Excess Tax Benefits from Share-Based Compensation	0	(884)
Net Change in Other Assets and Other Liabilities	(21,803)	(11,956)
Net Cash Provided by Operating Activities	97,919	74,380
Investment Securities Available-for-Sale:
Proceeds from Prepayments and Maturities	191,564	166,334
Proceeds from Sales	11,613	11,094
Purchases	(320,170)	(197,696)
Investment Securities Held-to-Maturity:
Proceeds from Prepayments and Maturities	406,904	352,035
Purchases	(365,498)	(178,347)
Net Change in Loans and Leases	(508,529)	(548,977)
Proceeds from Sales of Loans	112,357	19,055
Premises and Equipment, Net	(12,629)	(5,229)
Net Cash Used in Investing Activities	(484,388)	(381,731)
Financing Activities
Net Change in Deposits	464,409	392,704
Net Change in Short-Term Borrowings	(27,702)	(42,072)
Proceeds from Long-Term Debt	0	75,000
Repayments of Long-Term Debt	0	(50,000)
Excess Tax Benefits from Share-Based Compensation	0	884
Proceeds from Issuance of Common Stock	8,457	5,304
Repurchase of Common Stock	(21,287)	(37,010)
Cash Dividends Paid	(42,788)	(40,130)
Net Cash Provided by Financing Activities	381,089	304,680
Net Change in Cash and Cash Equivalents	(5,380)	(2,671)
Cash and Cash Equivalents at End of Period	874,227	753,050
Cash and Cash Equivalents at Beginning of Period	879,607	755,721
Supplemental Information
Cash Paid for Interest	21,498	19,469
Cash Paid for Income Taxes	32,058	42,229
Non-Cash Investing Activities:
Transfer from Loans to Foreclosed Real Estate	2,207	1,040
Transfers from Loans to Loans Held for Sale	$ 62,727	$ 101,282