Allowance for Loan and Lease Losses (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Allowance for loan losses [Roll Forward]
Beginning balance	$ 36,151	$ 35,933	$ 35,933
Provision charged to expense	946	1,229	7,521
Losses charged off	(2,977)	(2,491)	(11,085)
Recoveries	1,069	1,042	3,782
Ending balance	35,189	35,713	36,151
Ending balance [Abstract]
Individually evaluated for impairment	739	952	991
Collectively evaluated for impairment	34,450	34,761	35,160
Loans ending balance [Abstract]
Individually evaluated for impairment	48,185	50,300	47,412
Collectively evaluated for impairment	3,070,056	2,919,565	3,075,528
Commercial [Member] | Construction [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	686	884	884
Provision charged to expense	(14)	(242)	(237)
Losses charged off	0	(4)	(10)
Recoveries	14	6	49
Ending balance	686	644	686
Ending balance [Abstract]
Individually evaluated for impairment	0	25	25
Collectively evaluated for impairment	686	619	661
Loans ending balance [Abstract]
Individually evaluated for impairment	4,009	5,119	4,584
Collectively evaluated for impairment	74,638	64,658	71,895
Commercial [Member] | Real Estate [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	14,509	14,191	14,191
Provision charged to expense	(191)	189	2,281
Losses charged off	(210)	(210)	(2,038)
Recoveries	25	7	75
Ending balance	14,133	14,177	14,509
Ending balance [Abstract]
Individually evaluated for impairment	739	927	966
Collectively evaluated for impairment	13,394	13,250	13,543
Loans ending balance [Abstract]
Individually evaluated for impairment	33,389	32,452	31,465
Collectively evaluated for impairment	1,158,239	1,070,534	1,157,215
Commercial [Member] | Equipment Lease Financing [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	18	42	42
Provision charged to expense	5	(2)	(24)
Losses charged off	0	0	0
Recoveries	0	0	0
Ending balance	23	40	18
Ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	23	40	18
Loans ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	2,683	5,443	3,042
Commercial [Member] | Other [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	5,039	4,656	4,656
Provision charged to expense	(651)	419	1,744
Losses charged off	(236)	(419)	(1,893)
Recoveries	77	80	532
Ending balance	4,229	4,736	5,039
Ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	4,229	4,736	5,039
Loans ending balance [Abstract]
Individually evaluated for impairment	9,183	10,927	9,481
Collectively evaluated for impairment	329,452	339,579	341,553
Residential [Member] | Construction [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	660	629	629
Provision charged to expense	(4)	(58)	31
Losses charged off	(23)	0	0
Recoveries	0	0	0
Ending balance	633	571	660
Ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	633	571	660
Loans ending balance [Abstract]
Individually evaluated for impairment	318	0	318
Collectively evaluated for impairment	63,575	55,746	67,040
Residential [Member] | Real Estate [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	5,688	6,027	6,027
Provision charged to expense	435	(148)	189
Losses charged off	(193)	(66)	(615)
Recoveries	6	64	87
Ending balance	5,936	5,877	5,688
Ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	5,936	5,877	5,688
Loans ending balance [Abstract]
Individually evaluated for impairment	1,286	1,802	1,564
Collectively evaluated for impairment	717,472	702,753	708,006
Residential [Member] | Home Equity [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	857	774	774
Provision charged to expense	5	(15)	257
Losses charged off	(1)	(4)	(178)
Recoveries	1	2	4
Ending balance	862	757	857
Ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	862	757	857
Loans ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	99,593	91,330	99,356
Consumer [Member] | Consumer Direct [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	1,863	1,885	1,885
Provision charged to expense	80	94	418
Losses charged off	(216)	(270)	(965)
Recoveries	71	135	525
Ending balance	1,798	1,844	1,863
Ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	1,798	1,844	1,863
Loans ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	136,576	132,201	137,754
Consumer [Member] | Consumer Indirect [Member]
Allowance for loan losses [Roll Forward]
Beginning balance	6,831	6,845	6,845
Provision charged to expense	1,281	992	2,862
Losses charged off	(2,098)	(1,518)	(5,386)
Recoveries	875	748	2,510
Ending balance	6,889	7,067	6,831
Ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	6,889	7,067	6,831
Loans ending balance [Abstract]
Individually evaluated for impairment	0	0	0
Collectively evaluated for impairment	$ 487,828	$ 457,321	$ 489,667