Loans and Leases - Reserve for Loan and Lease Losses Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 25,652		$ 20,910	$ 21,555	$ 17,499
Charge-offs	(1,139)		(3,587)	(15,304)	(6,002)
Recoveries	113		531	913	1,146
Provision (recovery of provision)	2,744		2,690	20,205	7,899
Provision for acquired credit impaired loans	1		(1)	2	1
Ending balance	27,371	$ 25,652	20,543	27,371	20,543
Commercial, Financial and Agricultural [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	7,258		8,313	6,742	7,037
Charge-offs	(904)	(12,700)	(290)	(14,553)	(576)
Recoveries	22		325	271	722
Provision (recovery of provision)	813		(1,732)	14,729	(567)
Provision for acquired credit impaired loans	0		0	0	0
Ending balance	7,189	7,258	6,616	7,189	6,616
Real Estate-Commercial and Construction [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	12,327		8,468	9,839	7,505
Charge-offs	0		0	(40)	(30)
Recoveries	1		1	74	4
Provision (recovery of provision)	906		787	3,361	1,777
Provision for acquired credit impaired loans	0		0	0	0
Ending balance	13,234	12,327	9,256	13,234	9,256
Real Estate-Residential Secured for Business Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,004		1,129	1,661	774
Charge-offs	(30)		(56)	(30)	(1,237)
Recoveries	8		29	266	47
Provision (recovery of provision)	72		204	157	1,722
Provision for acquired credit impaired loans	0		(1)	0	(1)
Ending balance	2,054	2,004	1,305	2,054	1,305
Real Estate-Residential and Home Equity Secured for Personal Purpose [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,494		974	1,754	993
Charge-offs	0		(83)	0	(177)
Recoveries	6		68	71	89
Provision (recovery of provision)	527		756	1,201	808
Provision for acquired credit impaired loans	1		0	2	2
Ending balance	3,028	2,494	1,715	3,028	1,715
Loans to Individuals [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	447		329	373	364
Charge-offs	(82)		(61)	(253)	(301)
Recoveries	25		35	71	116
Provision (recovery of provision)	82		51	281	175
Provision for acquired credit impaired loans	0		0	0	0
Ending balance	472	447	354	472	354
Lease Financings [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,071		1,660	1,132	788
Charge-offs	(123)		(3,097)	(428)	(3,681)
Recoveries	51		73	160	168
Provision (recovery of provision)	138		2,654	273	4,015
Provision for acquired credit impaired loans	0		0	0	0
Ending balance	1,137	1,071	1,290	1,137	1,290
Unallocated Financing Receivables [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	51		37	54	38
Provision (recovery of provision)	206		(30)	203	(31)
Provision for acquired credit impaired loans	0		0	0	0
Ending balance	$ 257	$ 51	$ 7	$ 257	$ 7