Consolidated Condensed Statements Of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest and dividend income:
Interest and fees on loans	$ 64,496	$ 61,222	$ 128,898	$ 121,130
Interest and dividends on:
Obligations of U.S. Government, its agencies and other securities	7,746	6,892	14,513	14,030
Interest Income, Securities, State and Municipal	2,178	1,664	4,352	3,124
Other interest income	271	698	642	947
Total interest and dividend income	74,691	70,476	148,405	139,231
Interest on deposits:
Demand and savings deposits	4,107	2,291	7,397	3,905
Time deposits	2,886	2,457	5,437	4,618
Interest on borrowings:
Short-term borrowings	420	184	995	419
Long-term debt	2,536	5,766	4,984	11,559
Total interest expense	9,949	10,698	18,813	20,501
Net interest income	64,742	59,778	129,592	118,730
Provision for loan losses	1,386	4,581	1,646	5,457
Net interest income after provision for loan losses	63,356	55,197	127,946	113,273
Noninterest Income [Abstract]
Checkcard fee income	4,382	4,040	8,384	7,801
Bank owned life insurance income	1,031	1,114	2,040	2,217
ATM Fees	510	561	1,034	1,103
OREO valuation adjustments	(114)	(272)	(321)	(345)
Gain on sale of OREO, net	(147)	53	4,174	153
Gain (Loss) on Sale of Investments	0	0	(2,271)	0
Unrealized gain loss on equity securities	304	0	3,793	0
Other components of net periodic benefit income	1,705	1,448	3,410	2,896
Other	2,607	1,127	3,449	1,744
Total other income	23,242	20,699	50,145	39,654
Other expense:
Salaries and employee benefits	24,103	23,001	49,423	45,718
Employee Benefits and Share-based Compensation	7,630	6,206	14,659	12,674
Occupancy expense	2,570	2,565	5,506	5,200
Furniture and equipment expense	4,013	3,640	8,162	7,258
Data processing fees	1,902	1,676	3,675	3,641
Professional fees and services	6,123	6,018	12,313	10,847
Marketing	1,185	1,084	2,403	2,140
Insurance	1,196	1,517	2,624	3,087
Communication	1,189	1,155	2,439	2,488
Excise and Sales Taxes	958	943	2,063	2,006
Other expense	1,665	1,749	3,575	3,405
Total other expense	52,534	49,554	106,842	98,464
Income before income taxes	34,064	26,342	71,249	54,463
Income taxes	5,823	7,310	11,885	15,164
Net income	28,241	19,032	59,364	39,299
Net income available to common shareholders	$ 28,241	$ 19,032	$ 59,364	$ 39,299
Net income available to common shareholders
Basic	$ 1.85	$ 1.24	$ 3.88	$ 2.57
Diluted	$ 1.83	$ 1.24	$ 3.85	$ 2.55
Weighted average common shares outstanding
Basic	15,285,532	15,297,085	15,286,932	15,304,572
Diluted	15,417,607	15,398,865	15,424,585	15,415,765
Cash dividends declared	$ 1.21	$ 0.94	$ 2.15	$ 1.88
Fiduciary and Trust [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 6,666	$ 6,025	$ 13,061	$ 11,539
Deposit Account [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	2,826	3,156	5,748	6,295
Bank Servicing [Member]
Noninterest Income [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	3,472	3,447	7,644	6,251
Other	$ 3,500	$ 3,500	$ 7,600	$ 6,300