Consolidated Condensed Statements Of Income - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest and dividend income:
Interest and fees on loans	$ 78,737,000	$ 80,687,000
Interest and dividends on:
Obligations of U.S. Government, its agencies and other securities	4,256,000	5,531,000
Interest Income, Securities, State and Municipal	2,037,000	2,200,000
Other interest income	143,000	491,000
Total interest and dividend income	85,173,000	88,909,000
Interest on deposits:
Demand and savings deposits	386,000	6,342,000
Time deposits	1,584,000	4,285,000
Interest on borrowings:
Short-term borrowings	183,000	462,000
Long-term debt	2,286,000	1,537,000
Total interest expense	4,439,000	12,626,000
Net interest income	80,734,000	76,283,000
(Recovery of) provision for credit losses	(4,855,000)	5,153,000
Net interest income after provision for credit losses	85,589,000	71,130,000
Noninterest Income [Abstract]
Debit card fee income	6,086,000	4,960,000
Bank owned life insurance income	1,165,000	1,248,000
ATM Fees	530,000	412,000
Gains (Losses) on Sales of Other Real Estate	(33,000)	(196,000)
(Gain) loss on equity securities, net	1,810,000	(973,000)
Other components of net periodic benefit income	2,038,000	1,988,000
Other	2,649,000	1,640,000
Total other income	34,089,000	22,486,000
Other expense:
Salaries and employee benefits	29,896,000	28,429,000
Employee Benefits and Share-based Compensation	10,201,000	10,043,000
Occupancy expense	3,640,000	3,480,000
Furniture and equipment expense	2,610,000	4,319,000
Data processing fees	7,712,000	2,492,000
Professional fees and services	5,664,000	7,066,000
Marketing	1,491,000	1,486,000
Insurance	1,691,000	1,550,000
Communication	1,122,000	1,155,000
Excise and Sales Taxes	1,108,000	1,145,000
Amortization of Intangible Assets	479,000	606,000
Other expense	2,251,000	4,505,000
Total other expense	67,865,000	66,276,000
Income before income taxes	51,813,000	27,340,000
Income taxes	8,982,000	4,968,000
Net income	$ 42,831,000	$ 22,372,000
Net income available to common shareholders
Basic	$ 2.63	$ 1.37
Diluted	$ 2.61	$ 1.36
Weighted average common shares outstanding
Basic	16,314,987	16,303,602
Diluted	16,439,920	16,425,881
Cash dividends declared	$ 1.23	$ 1.22
Fiduciary and Trust [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 8,173,000	$ 7,113,000
Deposit Account [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	2,054,000	2,528,000
Bank Servicing [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 9,617,000	$ 3,766,000