Loans and Leases - Past Due Loans and Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	$ 9,466	$ 5,465
Loans and leases, current	3,513,020	3,408,869
Loans and leases, accruing	3,522,486	3,414,334
Non-accrual loans and leases	12,179	12,820
Total portfolio loans and leases	3,534,665	3,427,154
Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	8,014	3,872
Loans and leases, current	3,072,481	2,872,318
Loans and leases, accruing	3,080,495	2,876,190
Non-accrual loans and leases	8,354	9,061
Total portfolio loans and leases	3,088,849	2,885,251
Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,452	1,593
Loans and leases, current	440,539	536,551
Loans and leases, accruing	441,991	538,144
Non-accrual loans and leases	3,825	3,759
Total portfolio loans and leases	445,816	541,903
Administratively Delinquent
Financing Receivable, Past Due [Line Items]
Loans and leases, current		3,200
Commercial mortgage
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	716	1,072
Loans and leases, current	1,749,010	1,653,796
Loans and leases, accruing	1,749,726	1,654,868
Non-accrual loans and leases	6,072	2,568
Total portfolio loans and leases	1,755,798	1,657,436
Commercial mortgage | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	716	1,067
Loans and leases, current	1,472,300	1,326,320
Loans and leases, accruing	1,473,016	1,327,387
Non-accrual loans and leases	3,324	435
Total portfolio loans and leases	1,476,340	1,327,822
Commercial mortgage | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	5
Loans and leases, current	276,710	327,476
Loans and leases, accruing	276,710	327,481
Non-accrual loans and leases	2,748	2,133
Total portfolio loans and leases	279,458	329,614
Home equity loans and lines
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	310	92
Loans and leases, current	203,493	203,643
Loans and leases, accruing	203,803	203,735
Non-accrual loans and leases	49	3,616
Total portfolio loans and leases	203,852	207,351
Home equity loans and lines | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	310	25
Loans and leases, current	180,356	177,891
Loans and leases, accruing	180,666	177,916
Non-accrual loans and leases	49	3,590
Total portfolio loans and leases	180,715	181,506
Home equity loans and lines | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	67
Loans and leases, current	23,137	25,752
Loans and leases, accruing	23,137	25,819
Non-accrual loans and leases	0	26
Total portfolio loans and leases	23,137	25,845
Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	2,519	2,548
Loans and leases, current	502,873	488,355
Loans and leases, accruing	505,392	490,903
Non-accrual loans and leases	701	3,452
Total portfolio loans and leases	506,093	494,355
Residential mortgage | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,347	1,545
Loans and leases, current	431,127	406,664
Loans and leases, accruing	432,474	408,209
Non-accrual loans and leases	695	2,813
Total portfolio loans and leases	433,169	411,022
Residential mortgage | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,172	1,003
Loans and leases, current	71,746	81,691
Loans and leases, accruing	72,918	82,694
Non-accrual loans and leases	6	639
Total portfolio loans and leases	72,924	83,333
Construction
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,649	0
Loans and leases, current	150,905	181,078
Loans and leases, accruing	152,554	181,078
Non-accrual loans and leases	0	0
Total portfolio loans and leases	152,554	181,078
Construction | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,648	0
Loans and leases, current	147,776	174,592
Loans and leases, accruing	149,424	174,592
Non-accrual loans and leases	0	0
Total portfolio loans and leases	149,424	174,592
Construction | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1	0
Loans and leases, current	3,129	6,486
Loans and leases, accruing	3,130	6,486
Non-accrual loans and leases	0	0
Total portfolio loans and leases	3,130	6,486
Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	3,297	612
Loans and leases, current	696,375	692,871
Loans and leases, accruing	699,672	693,483
Non-accrual loans and leases	4,495	2,101
Total portfolio loans and leases	704,167	695,584
Commercial and industrial | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	3,072	612
Loans and leases, current	647,047	622,245
Loans and leases, accruing	650,119	622,857
Non-accrual loans and leases	3,785	1,786
Total portfolio loans and leases	653,904	624,643
Commercial and industrial | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	225	0
Loans and leases, current	49,328	70,626
Loans and leases, accruing	49,553	70,626
Non-accrual loans and leases	710	315
Total portfolio loans and leases	50,263	70,941
Consumer
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	125	40
Loans and leases, current	49,150	46,666
Loans and leases, accruing	49,275	46,706
Non-accrual loans and leases	60	108
Total portfolio loans and leases	49,335	46,814
Consumer | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	125	40
Loans and leases, current	46,648	44,014
Loans and leases, accruing	46,773	44,054
Non-accrual loans and leases	36	45
Total portfolio loans and leases	46,809	44,099
Consumer | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Loans and leases, current	2,502	2,652
Loans and leases, accruing	2,502	2,652
Non-accrual loans and leases	24	63
Total portfolio loans and leases	2,526	2,715
Leases
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	850	1,101
Loans and leases, current	161,214	142,460
Loans and leases, accruing	162,064	143,561
Non-accrual loans and leases	802	975
Total portfolio loans and leases	162,866	144,536
Leases | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	796	583
Loans and leases, current	147,227	120,592
Loans and leases, accruing	148,023	121,175
Non-accrual loans and leases	465	392
Total portfolio loans and leases	148,488	121,567
Leases | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	54	518
Loans and leases, current	13,987	21,868
Loans and leases, accruing	14,041	22,386
Non-accrual loans and leases	337	583
Total portfolio loans and leases	14,378	22,969
30 – 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	8,515	4,199
30 – 59 Days Past Due | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	7,376	3,051
30 – 59 Days Past Due | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,139	1,148
30 – 59 Days Past Due | Commercial mortgage
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	645	821
30 – 59 Days Past Due | Commercial mortgage | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	645	816
30 – 59 Days Past Due | Commercial mortgage | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	5
30 – 59 Days Past Due | Home equity loans and lines
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	60	92
30 – 59 Days Past Due | Home equity loans and lines | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	60	25
30 – 59 Days Past Due | Home equity loans and lines | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	67
30 – 59 Days Past Due | Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	2,404	2,330
30 – 59 Days Past Due | Residential mortgage | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,319	1,545
30 – 59 Days Past Due | Residential mortgage | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,085	785
30 – 59 Days Past Due | Construction
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,649	0
30 – 59 Days Past Due | Construction | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1,648	0
30 – 59 Days Past Due | Construction | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1	0
30 – 59 Days Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	3,072	280
30 – 59 Days Past Due | Commercial and industrial | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	3,072	280
30 – 59 Days Past Due | Commercial and industrial | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
30 – 59 Days Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	96	35
30 – 59 Days Past Due | Consumer | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	96	35
30 – 59 Days Past Due | Consumer | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
30 – 59 Days Past Due | Leases
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	589	641
30 – 59 Days Past Due | Leases | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	536	350
30 – 59 Days Past Due | Leases | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	53	291
60 – 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	951	1,266
60 – 89 Days Past Due | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	638	821
60 – 89 Days Past Due | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	313	445
60 – 89 Days Past Due | Commercial mortgage
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	71	251
60 – 89 Days Past Due | Commercial mortgage | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	71	251
60 – 89 Days Past Due | Commercial mortgage | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Home equity loans and lines
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	250	0
60 – 89 Days Past Due | Home equity loans and lines | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	250	0
60 – 89 Days Past Due | Home equity loans and lines | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	115	218
60 – 89 Days Past Due | Residential mortgage | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	28	0
60 – 89 Days Past Due | Residential mortgage | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	87	218
60 – 89 Days Past Due | Construction
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Construction | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Construction | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	225	332
60 – 89 Days Past Due | Commercial and industrial | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	332
60 – 89 Days Past Due | Commercial and industrial | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	225	0
60 – 89 Days Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	29	5
60 – 89 Days Past Due | Consumer | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	29	5
60 – 89 Days Past Due | Consumer | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
60 – 89 Days Past Due | Leases
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	261	460
60 – 89 Days Past Due | Leases | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	260	233
60 – 89 Days Past Due | Leases | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	1	227
Over 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial mortgage
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial mortgage | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial mortgage | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Home equity loans and lines
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Home equity loans and lines | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Home equity loans and lines | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Residential mortgage
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Residential mortgage | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Residential mortgage | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Construction
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Construction | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Construction | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial and industrial | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Commercial and industrial | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Consumer
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Consumer | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Consumer | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Leases
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Leases | Originated
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	0	0
Over 89 Days Past Due | Leases | Acquired
Financing Receivable, Past Due [Line Items]
Loans and leases, past due	$ 0	0
Originated Loans | Administratively Delinquent
Financing Receivable, Past Due [Line Items]
Loans and leases, current		2,000
Acquired Loans | Administratively Delinquent
Financing Receivable, Past Due [Line Items]
Loans and leases, current		$ 1,200