Loans and Leases - Past Due Loans and Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	$ 6,431	$ 5,465
Loans and leases, current	3,497,800	3,408,869
Loans and leases, accruing	3,504,231	3,414,334
Non-accrual loans and leases	19,283	12,820
Total portfolio loans and leases	3,523,514	3,427,154
Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	4,974	3,872
Loans and leases, current	3,011,545	2,872,318
Loans and leases, accruing	3,016,519	2,876,190
Non-accrual loans and leases	15,751	9,061
Total portfolio loans and leases	3,032,270	2,885,251
Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	1,457	1,593
Loans and leases, current	486,255	536,551
Loans and leases, accruing	487,712	538,144
Non-accrual loans and leases	3,532	3,759
Total portfolio loans and leases	491,244	541,903
Administratively Delinquent
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, current		3,200
Commercial mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	1,106	1,072
Loans and leases, current	1,740,031	1,653,796
Loans and leases, accruing	1,741,137	1,654,868
Non-accrual loans and leases	5,558	2,568
Total portfolio loans and leases	1,746,695	1,657,436
Commercial mortgage | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	1,106	1,067
Loans and leases, current	1,432,047	1,326,320
Loans and leases, accruing	1,433,153	1,327,387
Non-accrual loans and leases	3,458	435
Total portfolio loans and leases	1,436,611	1,327,822
Commercial mortgage | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	5
Loans and leases, current	307,984	327,476
Loans and leases, accruing	307,984	327,481
Non-accrual loans and leases	2,100	2,133
Total portfolio loans and leases	310,084	329,614
Home equity loans and lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	520	92
Loans and leases, current	197,367	203,643
Loans and leases, accruing	197,887	203,735
Non-accrual loans and leases	6,904	3,616
Total portfolio loans and leases	204,791	207,351
Home equity loans and lines | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	375	25
Loans and leases, current	172,822	177,891
Loans and leases, accruing	173,197	177,916
Non-accrual loans and leases	6,878	3,590
Total portfolio loans and leases	180,075	181,506
Home equity loans and lines | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	145	67
Loans and leases, current	24,545	25,752
Loans and leases, accruing	24,690	25,819
Non-accrual loans and leases	26	26
Total portfolio loans and leases	24,716	25,845
Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	2,677	2,548
Loans and leases, current	496,839	488,355
Loans and leases, accruing	499,516	490,903
Non-accrual loans and leases	2,863	3,452
Total portfolio loans and leases	502,379	494,355
Residential mortgage | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	1,968	1,545
Loans and leases, current	419,377	406,664
Loans and leases, accruing	421,345	408,209
Non-accrual loans and leases	2,293	2,813
Total portfolio loans and leases	423,638	411,022
Residential mortgage | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	709	1,003
Loans and leases, current	77,462	81,691
Loans and leases, accruing	78,171	82,694
Non-accrual loans and leases	570	639
Total portfolio loans and leases	78,741	83,333
Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Loans and leases, current	159,761	181,078
Loans and leases, accruing	159,761	181,078
Non-accrual loans and leases	0	0
Total portfolio loans and leases	159,761	181,078
Construction | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Loans and leases, current	157,572	174,592
Loans and leases, accruing	157,572	174,592
Non-accrual loans and leases	0	0
Total portfolio loans and leases	157,572	174,592
Construction | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Loans and leases, current	2,189	6,486
Loans and leases, accruing	2,189	6,486
Non-accrual loans and leases	0	0
Total portfolio loans and leases	2,189	6,486
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	764	612
Loans and leases, current	701,972	692,871
Loans and leases, accruing	702,736	693,483
Non-accrual loans and leases	2,965	2,101
Total portfolio loans and leases	705,701	695,584
Commercial and industrial | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	535	612
Loans and leases, current	648,012	622,245
Loans and leases, accruing	648,547	622,857
Non-accrual loans and leases	2,657	1,786
Total portfolio loans and leases	651,204	624,643
Commercial and industrial | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	229	0
Loans and leases, current	53,960	70,626
Loans and leases, accruing	54,189	70,626
Non-accrual loans and leases	308	315
Total portfolio loans and leases	54,497	70,941
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	128	40
Loans and leases, current	47,613	46,666
Loans and leases, accruing	47,741	46,706
Non-accrual loans and leases	80	108
Total portfolio loans and leases	47,821	46,814
Consumer | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	89	40
Loans and leases, current	45,104	44,014
Loans and leases, accruing	45,193	44,054
Non-accrual loans and leases	36	45
Total portfolio loans and leases	45,229	44,099
Consumer | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	39	0
Loans and leases, current	2,509	2,652
Loans and leases, accruing	2,548	2,652
Non-accrual loans and leases	44	63
Total portfolio loans and leases	2,592	2,715
Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	1,236	1,101
Loans and leases, current	154,217	142,460
Loans and leases, accruing	155,453	143,561
Non-accrual loans and leases	913	975
Total portfolio loans and leases	156,366	144,536
Leases | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	901	583
Loans and leases, current	136,611	120,592
Loans and leases, accruing	137,512	121,175
Non-accrual loans and leases	429	392
Total portfolio loans and leases	137,941	121,567
Leases | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	335	518
Loans and leases, current	17,606	21,868
Loans and leases, accruing	17,941	22,386
Non-accrual loans and leases	484	583
Total portfolio loans and leases	18,425	22,969
30 – 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	5,623	4,199
30 – 59 Days Past Due | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	4,312	3,051
30 – 59 Days Past Due | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	1,311	1,148
30 – 59 Days Past Due | Commercial mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	1,106	821
30 – 59 Days Past Due | Commercial mortgage | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	1,106	816
30 – 59 Days Past Due | Commercial mortgage | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	5
30 – 59 Days Past Due | Home equity loans and lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	376	92
30 – 59 Days Past Due | Home equity loans and lines | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	231	25
30 – 59 Days Past Due | Home equity loans and lines | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	145	67
30 – 59 Days Past Due | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	2,357	2,330
30 – 59 Days Past Due | Residential mortgage | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	1,735	1,545
30 – 59 Days Past Due | Residential mortgage | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	622	785
30 – 59 Days Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
30 – 59 Days Past Due | Construction | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
30 – 59 Days Past Due | Construction | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
30 – 59 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	749	280
30 – 59 Days Past Due | Commercial and industrial | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	520	280
30 – 59 Days Past Due | Commercial and industrial | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	229	0
30 – 59 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	64	35
30 – 59 Days Past Due | Consumer | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	25	35
30 – 59 Days Past Due | Consumer | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	39	0
30 – 59 Days Past Due | Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	971	641
30 – 59 Days Past Due | Leases | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	695	350
30 – 59 Days Past Due | Leases | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	276	291
60 – 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	808	1,266
60 – 89 Days Past Due | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	662	821
60 – 89 Days Past Due | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	146	445
60 – 89 Days Past Due | Commercial mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	251
60 – 89 Days Past Due | Commercial mortgage | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	251
60 – 89 Days Past Due | Commercial mortgage | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Home equity loans and lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	144	0
60 – 89 Days Past Due | Home equity loans and lines | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	144	0
60 – 89 Days Past Due | Home equity loans and lines | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	320	218
60 – 89 Days Past Due | Residential mortgage | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	233	0
60 – 89 Days Past Due | Residential mortgage | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	87	218
60 – 89 Days Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Construction | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Construction | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	15	332
60 – 89 Days Past Due | Commercial and industrial | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	15	332
60 – 89 Days Past Due | Commercial and industrial | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	64	5
60 – 89 Days Past Due | Consumer | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	64	5
60 – 89 Days Past Due | Consumer | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	265	460
60 – 89 Days Past Due | Leases | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	206	233
60 – 89 Days Past Due | Leases | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	59	227
Over 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial mortgage | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial mortgage | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Home equity loans and lines
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Home equity loans and lines | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Home equity loans and lines | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Residential mortgage | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Residential mortgage | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Construction | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Construction | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial and industrial | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial and industrial | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Consumer | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Consumer | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Leases | Originated
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Leases | Acquired
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, past due	$ 0	0
Originated Loans | Administratively Delinquent
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, current		2,000
Acquired Loans | Administratively Delinquent
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases, current		$ 1,200