Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Activities
Net Income	$ 58,799	$ 54,040
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Provision for Credit Losses	3,000	4,125
Depreciation and Amortization	3,996	3,339
Amortization of Deferred Loan and Lease Fees	(381)	(151)
Amortization and Accretion of Premiums/Discounts on Investment Securities, Net	5,290	8,966
Amortization of Operating Lease Right-of-Use Assets	3,185	0
Share-Based Compensation	2,274	1,867
Benefit Plan Contributions	(372)	(375)
Deferred Income Taxes	(2,363)	(138)
Gain (Loss) on Sale of Premises and Equipment	(558)	0
Net Gains on Sales of Loans and Leases	(1,065)	(573)
Net Losses (Gains) on Sales of Investment Securities	835	666
Proceeds from Sales of Loans Held for Sale	56,453	66,003
Originations of Loans Held for Sale	(63,014)	(70,290)
Net Tax Benefit from Share-Based Compensation	530	767
Net Change in Other Assets and Other Liabilities	(49,491)	6,632
Net Cash Provided by Operating Activities	17,118	74,878
Investment Securities Available-for-Sale:
Proceeds from Sales, Prepayments and Maturities	495,824	89,399
Purchases	(341,234)	(59,160)
Investment Securities Held-to-Maturity:
Proceeds from Prepayments and Maturities	177,841	195,199
Purchases	(367,178)	(59,598)
Net Change in Loans and Leases	(104,120)	(124,225)
Purchases of Premises and Equipment	(11,583)	(9,614)
Proceeds from Sale of Premises and Equipment	639	0
Net Cash Provided by (Used in) Investing Activities	(149,811)	32,001
Financing Activities
Net Change in Deposits	240,068	73,165
Net Change in Short-Term Borrowings	(196)	0
Repayments of Long-Term Debt	(25,019)	(25,000)
Proceeds from Issuance of Common Stock	1,994	1,959
Repurchase of Common Stock	(43,189)	(17,541)
Cash Dividends Paid	(25,646)	(22,087)
Net Cash Provided by Financing Activities	148,012	10,496
Net Change in Cash and Cash Equivalents	15,319	117,375
Cash and Cash Equivalents at End of Period	541,288	565,226
Cash and Cash Equivalents at Beginning of Period	525,969	447,851
Supplemental Information
Cash Paid for Interest	20,583	11,908
Cash Paid for Income Taxes	2,764	961
Non-Cash Investing and Financing Activities:
Transfer from Loans to Foreclosed Real Estate	1,869	1,728
Initial Recognition of Operating Lease Right-of-Use Assets	104,166	0
Initial Recognition of Operating Lease Liabilities	$ 111,230	$ 0