Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net income	$ 86,509	$ 80,413	$ 80,389
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization/accretion	16,617	22,647	20,626
Provision for Credit Losses	0	4,300	0
Net amortization of deferred loan fees	(5,576)	(4,442)	(260)
Stock option compensation expense	1,419	1,875	1,744
Life insurance gains	0	0	(433)
Securities gains	(34)	(71)	(217)
Gains on sales of premises and equipment	0	(3,536)	0
Gain on disposal of premises and equipment	0	(71)	0
Net changes in:
Interest income receivable	(2,499)	(4,225)	(2,963)
Net deferred tax liability	3,899	(246)	3,662
Increase in other assets	(3,534)	(3,528)	(14,806)
Income taxes payable	(1,054)	353	(1,733)
Interest expense payable	(72)	(5)	(9)
Other liabilities	(6,940)	14,280	(5,298)
Net Cash Provided by Operating Activities	88,735	107,744	80,702
Investing Activities:
Net repayments (disbursements) of loans	193,755	(126,682)	79,396
Proceeds from life insurance policies	0	0	1,273
Purchases of debt securities available for sale	(1,909,370)	(2,102,983)	(970,542)
Proceeds from sale/maturity/calls of debt securities available for sale	1,204,455	1,260,846	631,016
Proceeds from maturity/calls of debt securities held to maturity	206,400	218,164	238,450
Proceeds from sale of equity securities	0	0	1,797
Purchases of premises and equipment	(1,324)	(2,200)	(3,994)
Proceeds from sale of premises and equipment	0	3,819	0
Proceeds from sale of foreclosed assets	0	114	307
Net Cash Used in Investing Activities	(306,084)	(748,922)	(22,297)
Financing Activities
Net change in deposits	725,977	875,358	(54,218)
Net change in short-term borrowings	43,701	71,617	(20,319)
Exercise of stock options	3,017	2,838	13,699
Retirement of common stock	(232)	(16,496)	(488)
Common stock dividends paid	(44,304)	(44,285)	(43,942)
Net Cash Provided by (Used in) Financing Activities	728,159	889,032	(105,268)
Net Change In Cash and Due from Banks	510,810	247,854	(46,863)
Cash and Due from Banks at Beginning of Period	621,275	373,421	420,284
Cash and Due from Banks at End of Period	1,132,085	621,275	373,421
Supplemental disclosure of noncash activities:
Right-of-use assets acquired in exchange for operating lease liabilities	5,105	7,697	23,587
Amount recognized upon initial adoption of ASU 2016-02	0	0	15,325
Securities purchases pending settlement	0	29,000	0
Supplemental disclosure of cash flow activities:
Cash paid for amounts included in operating lease liabilities	6,309	6,516	5,123
Interest paid for the period	2,027	1,830	1,898
Income tax payments for the period	$ 27,673	$ 26,462	$ 24,491