Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Interest and Loan Fee Income:
Loans	$ 57,558	$ 59,377	$ 58,153
Equity securities	458	419	392
Debt securities available for sale	105,420	91,343	74,147
Debt securities held to maturity	8,875	13,552	18,997
Interest-bearing cash	1,132	1,165	6,993
Total Interest and Loan Fee Income	173,443	165,856	158,682
Interest Expense:
Deposits	1,877	1,770	1,854
Short-term borrowed funds	78	53	34
Other borrowed funds	0	1	0
Total Interest Expense	1,955	1,824	1,888
Net interest income	171,488	164,032	156,794
Provision for Credit Losses	0	4,300	0
Net Interest and Loan Fee Income After Provision For Credit Losses	171,488	159,732	156,794
Noninterest Income:
Gains on sales of real property	0	3,536	0
Life insurance gains	0	0	433
Securities gains	34	71	217
Other noninterest income	2,926	3,998	4,001
Total Noninterest Income	43,345	45,637	47,408
Noninterest Expense:
Salaries and benefits	48,011	50,749	51,054
Occupancy and equipment	19,139	19,637	20,240
Outsourced data processing services	9,601	9,426	9,471
Professional fees	3,253	2,423	2,465
Courier service	2,177	2,001	1,878
Loss contingency	0	0	553
Amortization of identifiable intangibles	269	287	538
Other noninterest expense	15,356	14,043	12,787
Total Noninterest Expense	97,806	98,566	98,986
Income Before Income Taxes	117,027	106,803	105,216
Provision for income taxes	30,518	26,390	24,827
Net Income	$ 86,509	$ 80,413	$ 80,389
Average Common Shares Outstanding (in shares)	26,855	26,942	26,956
Diluted Average Common Shares Outstanding (in shares)	26,870	26,960	27,006
Per Common Share Data:
Basic earnings (in dollars per share)	$ 3.22	$ 2.98	$ 2.98
Diluted earnings (in dollars per share)	3.22	2.98	2.98
Dividends paid per common share (in dollars per share)	$ 1.65	$ 1.64	$ 1.63
Deposit Account [Member]
Noninterest Income:
Noninterest income revenue	$ 13,697	$ 14,149	$ 17,882
Credit Card, Merchant Discount [Member]
Noninterest Income:
Noninterest income revenue	11,998	10,208	10,132
Debit Card [Member]
Noninterest Income:
Noninterest income revenue	6,859	6,181	6,357
Fiduciary and Trust [Member]
Noninterest Income:
Noninterest income revenue	3,311	3,012	2,963
ATM Processing Fees [Member]
Noninterest Income:
Noninterest income revenue	2,280	2,273	2,776
Financial Service, Other [Member]
Noninterest Income:
Noninterest income revenue	1,884	1,837	2,255
Financial Services Commission [Member]
Noninterest Income:
Noninterest income revenue	$ 356	$ 372	$ 392