Consolidated Condensed Statements Of Income - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Interest and dividend income:
Interest and fees on loans	$ 72,416,000	$ 78,737,000
Interest and dividends on:
Obligations of U.S. Government, its agencies and other securities	6,130,000	4,256,000
Interest Income, Securities, State and Municipal	2,447,000	2,037,000
Other interest income	153,000	143,000
Total interest and dividend income	81,146,000	85,173,000
Interest on deposits:
Demand and savings deposits	351,000	386,000
Time deposits	720,000	1,584,000
Interest on borrowings:
Short-term borrowings	244,000	183,000
Long-term debt	2,145,000	2,286,000
Total interest expense	3,460,000	4,439,000
Net interest income	77,686,000	80,734,000
Recovery of credit losses	(4,605,000)	(4,855,000)
Net interest income after provision for credit losses	82,291,000	85,589,000
Noninterest Income [Abstract]
Debit card fee income	6,126,000	6,086,000
Bank owned life insurance income	1,175,000	1,165,000
ATM Fees	532,000	530,000
Gains (Losses) on Sales of Other Real Estate	0	(33,000)
Gain on equity securities, net	2,353,000	1,810,000
Other components of net periodic benefit income	3,027,000	2,038,000
Other	2,753,000	2,649,000
Total other income	31,656,000	34,089,000
Other expense:
Salaries and employee benefits	30,521,000	29,896,000
Employee Benefits and Share-based Compensation	10,499,000	10,201,000
Occupancy expense	3,214,000	3,640,000
Furniture and equipment expense	2,937,000	2,610,000
Data processing fees	7,504,000	7,712,000
Professional fees and services	5,858,000	5,664,000
Marketing	1,317,000	1,491,000
Insurance	1,405,000	1,691,000
Communication	890,000	1,122,000
Excise and Sales Taxes	1,192,000	1,108,000
Amortization of Intangible Assets	402,000	479,000
Other expense	1,634,000	2,251,000
Total other expense	67,373,000	67,865,000
Income before income taxes	46,574,000	51,813,000
Income taxes	7,699,000	8,982,000
Net income	$ 38,875,000	$ 42,831,000
Net income available to common shareholders
Basic	$ 2.40	$ 2.63
Diluted	$ 2.38	$ 2.61
Weighted average common shares outstanding
Basic	16,219,889	16,314,987
Diluted	16,331,031	16,439,920
Quarterly Dividend
Weighted average common shares outstanding
Cash dividends declared	$ 1.04	$ 1.03
Special Dividend
Weighted average common shares outstanding
Cash dividends declared	$ 0	$ 0.20
Fiduciary and Trust [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 8,797,000	$ 8,173,000
Deposit Account [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	2,074,000	2,054,000
Bank Servicing [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 4,819,000	$ 9,617,000