Loans and Leases - Allowance for Loan and Lease Losses by Method of Impairment (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Allowance on loans and leases:
Individually evaluated for impairment	$ 460		$ 462
Collectively evaluated for impairment	20,722		18,964
Allowance on loans and leases	21,182	$ 20,616	19,426	$ 19,398	$ 17,662	$ 17,525
Carrying value of loans and leases:
Individually evaluated for impairment	16,290		21,377
Collectively evaluated for impairment	3,507,530		3,393,473
Portfolio loans and leases	3,534,665		3,427,154
Purchased credit-impaired
Allowance on loans and leases:
Allowance on loans and leases	0		0
Carrying value of loans and leases:
Portfolio loans and leases	10,845		12,304
Originated
Allowance on loans and leases:
Individually evaluated for impairment	357		365
Collectively evaluated for impairment	20,719		18,964
Allowance on loans and leases	21,076		19,329
Carrying value of loans and leases:
Individually evaluated for impairment	11,931		17,337
Collectively evaluated for impairment	3,076,918		2,867,914
Portfolio loans and leases	3,088,849		2,885,251
Acquired
Carrying value of loans and leases:
Individually evaluated for impairment	4,359		4,040
Collectively evaluated for impairment	430,612		525,559
Portfolio loans and leases	445,816		541,903
Financial Asset Acquired With and Without Credit Deterioration
Allowance on loans and leases:
Individually evaluated for impairment	103		97
Collectively evaluated for impairment	3		0
Allowance on loans and leases	106		97
Commercial mortgage
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	8,958		7,567
Allowance on loans and leases	8,958	8,241	7,567	8,033	7,174	7,550
Carrying value of loans and leases:
Individually evaluated for impairment	6,071		7,008
Collectively evaluated for impairment	1,742,871		1,642,117
Portfolio loans and leases	1,755,798		1,657,436
Commercial mortgage | Purchased credit-impaired
Allowance on loans and leases:
Allowance on loans and leases	0		0
Carrying value of loans and leases:
Portfolio loans and leases	6,856		8,311
Commercial mortgage | Originated
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	8,958		7,567
Allowance on loans and leases	8,958		7,567
Carrying value of loans and leases:
Individually evaluated for impairment	3,323		4,874
Collectively evaluated for impairment	1,473,017		1,322,948
Portfolio loans and leases	1,476,340		1,327,822
Commercial mortgage | Acquired
Carrying value of loans and leases:
Individually evaluated for impairment	2,748		2,134
Collectively evaluated for impairment	269,854		319,169
Portfolio loans and leases	279,458		329,614
Commercial mortgage | Financial Asset Acquired With and Without Credit Deterioration
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	0		0
Allowance on loans and leases	0		0
Home equity loans and lines
Allowance on loans and leases:
Individually evaluated for impairment	153		162
Collectively evaluated for impairment	890		841
Allowance on loans and leases	1,043	1,038	1,003	933	1,045	1,086
Carrying value of loans and leases:
Individually evaluated for impairment	1,493		4,998
Collectively evaluated for impairment	201,843		201,841
Portfolio loans and leases	203,852		207,351
Home equity loans and lines | Purchased credit-impaired
Allowance on loans and leases:
Allowance on loans and leases	0		0
Carrying value of loans and leases:
Portfolio loans and leases	516		512
Home equity loans and lines | Originated
Allowance on loans and leases:
Individually evaluated for impairment	153		162
Collectively evaluated for impairment	890		841
Allowance on loans and leases	1,043		1,003
Carrying value of loans and leases:
Individually evaluated for impairment	1,493		4,972
Collectively evaluated for impairment	179,222		176,534
Portfolio loans and leases	180,715		181,506
Home equity loans and lines | Acquired
Carrying value of loans and leases:
Individually evaluated for impairment	0		26
Collectively evaluated for impairment	22,621		25,307
Portfolio loans and leases	23,137		25,845
Home equity loans and lines | Financial Asset Acquired With and Without Credit Deterioration
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	0		0
Allowance on loans and leases	0		0
Residential mortgage
Allowance on loans and leases:
Individually evaluated for impairment	264		272
Collectively evaluated for impairment	1,629		1,541
Allowance on loans and leases	1,893	1,891	1,813	1,933	1,898	1,926
Carrying value of loans and leases:
Individually evaluated for impairment	3,736		6,608
Collectively evaluated for impairment	502,355		487,747
Portfolio loans and leases	506,093		494,355
Residential mortgage | Purchased credit-impaired
Allowance on loans and leases:
Allowance on loans and leases	0		0
Carrying value of loans and leases:
Portfolio loans and leases	2		0
Residential mortgage | Originated
Allowance on loans and leases:
Individually evaluated for impairment	167		175
Collectively evaluated for impairment	1,629		1,541
Allowance on loans and leases	1,796		1,716
Carrying value of loans and leases:
Individually evaluated for impairment	2,878		5,106
Collectively evaluated for impairment	430,291		405,916
Portfolio loans and leases	433,169		411,022
Residential mortgage | Acquired
Carrying value of loans and leases:
Individually evaluated for impairment	858		1,502
Collectively evaluated for impairment	72,064		81,831
Portfolio loans and leases	72,924		83,333
Residential mortgage | Financial Asset Acquired With and Without Credit Deterioration
Allowance on loans and leases:
Individually evaluated for impairment	97		97
Collectively evaluated for impairment	0		0
Allowance on loans and leases	97		97
Construction
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	1,086		1,485
Allowance on loans and leases	1,086	1,186	1,485	1,158	844	937
Carrying value of loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	150,107		178,673
Portfolio loans and leases	152,554		181,078
Construction | Purchased credit-impaired
Allowance on loans and leases:
Allowance on loans and leases	0		0
Carrying value of loans and leases:
Portfolio loans and leases	2,447		2,405
Construction | Originated
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	1,086		1,485
Allowance on loans and leases	1,086		1,485
Carrying value of loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	149,424		174,592
Portfolio loans and leases	149,424		174,592
Construction | Acquired
Carrying value of loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	683		4,081
Portfolio loans and leases	3,130		6,486
Construction | Financial Asset Acquired With and Without Credit Deterioration
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	0		0
Allowance on loans and leases	0		0
Commercial and industrial
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	5,700		5,461
Allowance on loans and leases	5,700	5,888	5,461	5,672	5,361	5,038
Carrying value of loans and leases:
Individually evaluated for impairment	4,886		2,629
Collectively evaluated for impairment	698,257		691,879
Portfolio loans and leases	704,167		695,584
Commercial and industrial | Purchased credit-impaired
Allowance on loans and leases:
Allowance on loans and leases	0		0
Carrying value of loans and leases:
Portfolio loans and leases	1,024		1,076
Commercial and industrial | Originated
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	5,700		5,461
Allowance on loans and leases	5,700		5,461
Carrying value of loans and leases:
Individually evaluated for impairment	4,176		2,314
Collectively evaluated for impairment	649,728		622,329
Portfolio loans and leases	653,904		624,643
Commercial and industrial | Acquired
Carrying value of loans and leases:
Individually evaluated for impairment	710		315
Collectively evaluated for impairment	48,529		69,550
Portfolio loans and leases	50,263		70,941
Commercial and industrial | Financial Asset Acquired With and Without Credit Deterioration
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	0		0
Allowance on loans and leases	0		0
Consumer
Allowance on loans and leases:
Individually evaluated for impairment	43		28
Collectively evaluated for impairment	210		201
Allowance on loans and leases	253	328	229	289	291	246
Carrying value of loans and leases:
Individually evaluated for impairment	104		134
Collectively evaluated for impairment	49,231		46,680
Portfolio loans and leases	49,335		46,814
Consumer | Purchased credit-impaired
Allowance on loans and leases:
Allowance on loans and leases	0		0
Carrying value of loans and leases:
Portfolio loans and leases	0		0
Consumer | Originated
Allowance on loans and leases:
Individually evaluated for impairment	37		28
Collectively evaluated for impairment	210		201
Allowance on loans and leases	247		229
Carrying value of loans and leases:
Individually evaluated for impairment	61		71
Collectively evaluated for impairment	46,748		44,028
Portfolio loans and leases	46,809		44,099
Consumer | Acquired
Carrying value of loans and leases:
Individually evaluated for impairment	43		63
Collectively evaluated for impairment	2,483		2,652
Portfolio loans and leases	2,526		2,715
Consumer | Financial Asset Acquired With and Without Credit Deterioration
Allowance on loans and leases:
Individually evaluated for impairment	6		0
Collectively evaluated for impairment	0		0
Allowance on loans and leases	6		0
Leases
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	2,249		1,868
Allowance on loans and leases	2,249	$ 2,044	1,868	$ 1,380	$ 1,049	$ 742
Carrying value of loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	162,866		144,536
Portfolio loans and leases	162,866		144,536
Leases | Purchased credit-impaired
Allowance on loans and leases:
Allowance on loans and leases	0		0
Carrying value of loans and leases:
Portfolio loans and leases	0		0
Leases | Originated
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	2,246		1,868
Allowance on loans and leases	2,246		1,868
Carrying value of loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	148,488		121,567
Portfolio loans and leases	148,488		121,567
Leases | Acquired
Carrying value of loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	14,378		22,969
Portfolio loans and leases	14,378		22,969
Leases | Financial Asset Acquired With and Without Credit Deterioration
Allowance on loans and leases:
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	3		0
Allowance on loans and leases	$ 3		$ 0