Loans, Credit Risk Profile Based on Rating Category and Payment Activity and on Performing and Nonperforming Status, Segregated by Class (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Dec. 31, 2018
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		$ 3,189,732	$ 3,208,638
Consumer mortgage loans secured by real estate properties for which formal foreclosure proceedings are in process		3,000	3,300
Commercial [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		1,647,582	1,644,746
Commercial [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		$ 1,438,598	1,441,702
Commercial [Member] | Pass [Member] | Minimum [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Review period for loans		12 months
Commercial [Member] | Pass [Member] | Maximum [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Review period for loans		18 months
Commercial [Member] | Watch [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		$ 105,653	103,890
Commercial [Member] | OAEM [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		26,135	27,063
Commercial [Member] | Substandard [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		77,036	71,924
Commercial [Member] | Doubtful [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		160	167
Commercial [Member] | Construction [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		75,364	82,715
Commercial [Member] | Construction [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		67,224	74,222
Commercial [Member] | Construction [Member] | Watch [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		2,932	3,070
Commercial [Member] | Construction [Member] | OAEM [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		1,823	1,594
Commercial [Member] | Construction [Member] | Substandard [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		3,385	3,829
Commercial [Member] | Construction [Member] | Doubtful [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		0	0
Commercial [Member] | Real Estate [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		1,182,804	1,183,093
Commercial [Member] | Real Estate [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		1,031,325	1,038,309
Commercial [Member] | Real Estate [Member] | Watch [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		75,404	71,834
Commercial [Member] | Real Estate [Member] | OAEM [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		18,501	19,734
Commercial [Member] | Real Estate [Member] | Substandard [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		57,485	53,125
Commercial [Member] | Real Estate [Member] | Doubtful [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		89	91
Commercial [Member] | Equipment Leases [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		1,354	1,740
Commercial [Member] | Equipment Leases [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		1,354	1,740
Commercial [Member] | Equipment Leases [Member] | Watch [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		0	0
Commercial [Member] | Equipment Leases [Member] | OAEM [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		0	0
Commercial [Member] | Equipment Leases [Member] | Substandard [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		0	0
Commercial [Member] | Equipment Leases [Member] | Doubtful [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		0	0
Commercial [Member] | Other [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		388,060	377,198
Commercial [Member] | Other [Member] | Pass [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		338,695	327,431
Commercial [Member] | Other [Member] | Watch [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		27,317	28,986
Commercial [Member] | Other [Member] | OAEM [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		5,811	5,735
Commercial [Member] | Other [Member] | Substandard [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		16,166	14,970
Commercial [Member] | Other [Member] | Doubtful [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		71	76
Residential [Member] | Construction [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		54,013	57,160
Residential [Member] | Construction [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		53,718	57,132
Residential [Member] | Construction [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile	[1]	295	28
Residential [Member] | Real Estate [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		720,292	722,417
Residential [Member] | Real Estate [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		711,398	712,927
Residential [Member] | Real Estate [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile	[1]	8,894	9,490
Residential [Member] | Home Equity [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		108,018	106,299
Residential [Member] | Home Equity [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		107,275	105,576
Residential [Member] | Home Equity [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile	[1]	743	723
Consumer [Member] | Consumer Direct [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		141,855	144,289
Consumer [Member] | Consumer Direct [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		141,825	144,215
Consumer [Member] | Consumer Direct [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile	[1]	30	74
Consumer [Member] | Consumer Indirect [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		517,972	533,727
Consumer [Member] | Consumer Indirect [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		517,582	533,221
Consumer [Member] | Consumer Indirect [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile	[1]	390	506
Residential and Consumer Portfolio Segments [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		1,542,150	1,563,892
Residential and Consumer Portfolio Segments [Member] | Performing [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile		1,531,798	1,553,071
Residential and Consumer Portfolio Segments [Member] | Nonperforming [Member]
Credit Risk Profile, Segregated by Class [Abstract]
Loan portfolio based on credit risk profile	[1]	$ 10,352	$ 10,821

[1] A loan is considered nonperforming if it is 90 days or more past due and/or on nonaccrual.