Loans and Leases - Allowance for Loan and Lease Losses by Method of Impairment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	$ 462	$ 258
Collectively evaluated for impairment	18,964	17,267
Allowance on loans and leases	19,426	17,525	$ 17,486
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	21,377	13,940
Collectively evaluated for impairment	3,393,473	3,241,069
Total portfolio loans and leases	3,427,154	3,285,858
Originated
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	365	208
Collectively evaluated for impairment	18,964	17,267
Allowance on loans and leases	19,329	17,475
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	17,337	8,878
Collectively evaluated for impairment	2,867,914	2,478,418
Total portfolio loans and leases	2,885,251	2,487,296
Acquired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	97	50
Collectively evaluated for impairment	0	0
Allowance on loans and leases	97	50
Acquired
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	4,040	5,062
Collectively evaluated for impairment	525,559	762,651
Total portfolio loans and leases	541,903	798,562
Purchased credit impaired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance on loans and leases	0	0
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total portfolio loans and leases	12,304	30,849
Commercial mortgage
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	7,567	7,550
Allowance on loans and leases	7,567	7,550	6,227
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	7,008	2,128
Collectively evaluated for impairment	1,642,117	1,503,825
Total portfolio loans and leases	1,657,436	1,523,377
Commercial mortgage | Originated
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	7,567	7,550
Allowance on loans and leases	7,567	7,550
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	4,874	1,345
Collectively evaluated for impairment	1,322,948	1,120,982
Total portfolio loans and leases	1,327,822	1,122,327
Commercial mortgage | Acquired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	0	0
Allowance on loans and leases	0	0
Commercial mortgage | Acquired
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	2,134	783
Collectively evaluated for impairment	319,169	382,843
Total portfolio loans and leases	329,614	401,050
Commercial mortgage | Purchased credit impaired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance on loans and leases	0	0
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total portfolio loans and leases	8,311	17,424
Home equity lines and loans
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	162	19
Collectively evaluated for impairment	841	1,067
Allowance on loans and leases	1,003	1,086	1,255
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	4,998	2,162
Collectively evaluated for impairment	201,841	215,604
Total portfolio loans and leases	207,351	218,275
Home equity lines and loans | Originated
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	162	19
Collectively evaluated for impairment	841	1,067
Allowance on loans and leases	1,003	1,086
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	4,972	1,902
Collectively evaluated for impairment	176,534	181,381
Total portfolio loans and leases	181,506	183,283
Home equity lines and loans | Acquired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	0	0
Allowance on loans and leases	0	0
Home equity lines and loans | Acquired
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	26	260
Collectively evaluated for impairment	25,307	34,223
Total portfolio loans and leases	25,845	34,992
Home equity lines and loans | Purchased credit impaired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance on loans and leases	0	0
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total portfolio loans and leases	512	509
Residential mortgage
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	272	230
Collectively evaluated for impairment	1,541	1,696
Allowance on loans and leases	1,813	1,926	1,917
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	6,608	7,726
Collectively evaluated for impairment	487,747	451,160
Total portfolio loans and leases	494,355	458,886
Residential mortgage | Originated
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	175	180
Collectively evaluated for impairment	1,541	1,696
Allowance on loans and leases	1,716	1,876
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	5,106	4,418
Collectively evaluated for impairment	405,916	356,517
Total portfolio loans and leases	411,022	360,935
Residential mortgage | Acquired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	97	50
Collectively evaluated for impairment	0	0
Allowance on loans and leases	97	50
Residential mortgage | Acquired
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	1,502	3,308
Collectively evaluated for impairment	81,831	94,643
Total portfolio loans and leases	83,333	97,951
Residential mortgage | Purchased credit impaired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance on loans and leases	0	0
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total portfolio loans and leases	0	0
Construction
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,485	937
Allowance on loans and leases	1,485	937	2,233
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	178,673	204,088
Total portfolio loans and leases	181,078	212,454
Construction | Originated
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,485	937
Allowance on loans and leases	1,485	937
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	174,592	128,266
Total portfolio loans and leases	174,592	128,266
Construction | Acquired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	0	0
Allowance on loans and leases	0	0
Construction | Acquired
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	4,081	75,822
Total portfolio loans and leases	6,486	84,188
Construction | Purchased credit impaired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance on loans and leases	0	0
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total portfolio loans and leases	2,405	8,366
Commercial and industrial
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	5
Collectively evaluated for impairment	5,461	5,033
Allowance on loans and leases	5,461	5,038	5,142
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	2,629	1,897
Collectively evaluated for impairment	691,879	712,865
Total portfolio loans and leases	695,584	719,312
Commercial and industrial | Originated
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	5
Collectively evaluated for impairment	5,461	5,033
Allowance on loans and leases	5,461	5,038
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	2,314	1,186
Collectively evaluated for impairment	622,329	588,118
Total portfolio loans and leases	624,643	589,304
Commercial and industrial | Acquired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	0	0
Allowance on loans and leases	0	0
Commercial and industrial | Acquired
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	315	711
Collectively evaluated for impairment	69,550	124,747
Total portfolio loans and leases	70,941	130,008
Commercial and industrial | Purchased credit impaired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance on loans and leases	0	0
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total portfolio loans and leases	1,076	4,550
Consumer
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	28	4
Collectively evaluated for impairment	201	242
Allowance on loans and leases	229	246	153
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	134	27
Collectively evaluated for impairment	46,680	38,126
Total portfolio loans and leases	46,814	38,153
Consumer | Originated
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	28	4
Collectively evaluated for impairment	201	242
Allowance on loans and leases	229	246
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	71	27
Collectively evaluated for impairment	44,028	35,119
Total portfolio loans and leases	44,099	35,146
Consumer | Acquired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	0	0
Allowance on loans and leases	0	0
Consumer | Acquired
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	63	0
Collectively evaluated for impairment	2,652	3,007
Total portfolio loans and leases	2,715	3,007
Consumer | Purchased credit impaired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance on loans and leases	0	0
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total portfolio loans and leases	0	0
Leases
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,868	742
Allowance on loans and leases	1,868	742	$ 559
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	144,536	115,401
Total portfolio loans and leases	144,536	115,401
Leases | Originated
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	1,868	742
Allowance on loans and leases	1,868	742
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	121,567	68,035
Total portfolio loans and leases	121,567	68,035
Leases | Acquired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	0	0
Allowance on loans and leases	0	0
Leases | Acquired
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	22,969	47,366
Total portfolio loans and leases	22,969	47,366
Leases | Purchased credit impaired
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance on loans and leases	0	0
Loans and Leases Receivable, Gross, Carrying Amount [Abstract]
Total portfolio loans and leases	$ 0	$ 0