Loans and Leases - Reserve for Loan and Lease Losses Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 32,600	$ 25,652	$ 29,364	$ 21,555
Charge-offs	(844)	(1,139)	(2,769)	(15,304)
Recoveries	376	113	776	913
Provision (recovery of provision)	1,524	2,744	6,284	20,205
Provision for acquired credit impaired loans	6	1	7	2
Ending balance	33,662	27,371	33,662	27,371
Commercial, Financial and Agricultural [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	9,129	7,258	7,983	6,742
Charge-offs	(283)	(904)	(1,769)	(14,553)
Recoveries	182	22	283	271
Provision (recovery of provision)	222	813	2,753	14,729
Provision for acquired credit impaired loans	0	0	0	0
Ending balance	9,250	7,189	9,250	7,189
Real Estate Commercial And Construction [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	15,478	12,327	13,903	9,839
Charge-offs	(251)	0	(325)	(40)
Recoveries	1	1	92	74
Provision (recovery of provision)	593	906	2,151	3,361
Provision for acquired credit impaired loans	0	0	0	0
Ending balance	15,821	13,234	15,821	13,234
Real Estate-Residential Secured For Business Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,478	2,004	2,236	1,661
Charge-offs	0	(30)	0	(30)
Recoveries	98	8	108	266
Provision (recovery of provision)	103	72	335	157
Provision for acquired credit impaired loans	6	0	6	0
Ending balance	2,685	2,054	2,685	2,054
Residential And Home Equity Secured For Personal Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,518	2,494	3,199	1,754
Charge-offs	(183)	0	(198)	0
Recoveries	4	6	16	71
Provision (recovery of provision)	273	527	594	1,201
Provision for acquired credit impaired loans	0	1	1	2
Ending balance	3,612	3,028	3,612	3,028
Loans to Individuals [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	481	447	484	373
Charge-offs	(73)	(82)	(209)	(253)
Recoveries	20	25	58	71
Provision (recovery of provision)	47	82	142	281
Provision for acquired credit impaired loans	0	0	0	0
Ending balance	475	472	475	472
Lease Financings [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,241	1,071	1,288	1,132
Charge-offs	(54)	(123)	(268)	(428)
Recoveries	71	51	219	160
Provision (recovery of provision)	(24)	138	(5)	273
Provision for acquired credit impaired loans	0	0	0	0
Ending balance	1,234	1,137	1,234	1,137
Unallocated Financing Receivables [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	275	51	271	54
Provision (recovery of provision)	310	206	314	203
Provision for acquired credit impaired loans	0	0	0	0
Ending balance	$ 585	$ 257	$ 585	$ 257