Loans - Impaired Loans by Class (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 70,756	$ 70,051
Unpaid Principal Balance	76,594	75,511
Related Valuation Allowance	8,638	6,804
Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	68,448	60,822
Unpaid Principal Balance	71,860	64,378
Related Valuation Allowance	0	0
Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	139,204	130,873
Unpaid Principal Balance	148,454	139,889
Related Valuation Allowance	8,638	6,804
Commercial | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	27,102	20,957
Unpaid Principal Balance	29,617	23,781
Related Valuation Allowance	4,971	3,546
Commercial | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	23,748	25,093
Unpaid Principal Balance	24,800	25,934
Related Valuation Allowance	0	0
Commercial | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	50,850	46,050
Unpaid Principal Balance	54,417	49,715
Related Valuation Allowance	4,971	3,546
Total commercial real estate | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	24,855	32,543
Unpaid Principal Balance	28,178	35,179
Related Valuation Allowance	2,121	1,917
Total commercial real estate | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	34,798	26,208
Unpaid Principal Balance	37,158	28,923
Related Valuation Allowance	0	0
Total commercial real estate | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	59,653	58,751
Unpaid Principal Balance	65,336	64,102
Related Valuation Allowance	2,121	1,917
Real estate construction and land development | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	3,776	126
Unpaid Principal Balance	3,776	126
Related Valuation Allowance	486	11
Real estate construction and land development | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	147	111
Unpaid Principal Balance	147	111
Related Valuation Allowance	0	0
Real estate construction and land development | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	3,923	237
Unpaid Principal Balance	3,923	237
Related Valuation Allowance	486	11
Residential mortgage | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	9,961	10,867
Unpaid Principal Balance	9,961	10,867
Related Valuation Allowance	711	816
Residential mortgage | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	7,581	7,537
Unpaid Principal Balance	7,581	7,537
Related Valuation Allowance	0	0
Residential mortgage | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	17,542	18,404
Unpaid Principal Balance	17,542	18,404
Related Valuation Allowance	711	816
Consumer installment | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,051	1,126
Unpaid Principal Balance	1,051	1,126
Related Valuation Allowance	103	186
Consumer installment | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	368	377
Unpaid Principal Balance	368	377
Related Valuation Allowance	0	0
Consumer installment | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,419	1,503
Unpaid Principal Balance	1,419	1,503
Related Valuation Allowance	103	186
Home equity | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	4,011	4,432
Unpaid Principal Balance	4,011	4,432
Related Valuation Allowance	246	328
Home equity | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,806	1,496
Unpaid Principal Balance	1,806	1,496
Related Valuation Allowance	0	0
Home equity | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	5,817	5,928
Unpaid Principal Balance	5,817	5,928
Related Valuation Allowance	246	328
Owner-occupied | Commercial | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	19,116	14,702
Unpaid Principal Balance	21,157	16,519
Related Valuation Allowance	1,619	1,359
Owner-occupied | Commercial | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	11,964	10,971
Unpaid Principal Balance	12,825	11,601
Related Valuation Allowance	0	0
Owner-occupied | Commercial | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	31,080	25,673
Unpaid Principal Balance	33,982	28,120
Related Valuation Allowance	1,619	1,359
Non-owner occupied | Commercial | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	4,739	16,833
Unpaid Principal Balance	5,816	17,452
Related Valuation Allowance	392	462
Non-owner occupied | Commercial | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	21,186	12,412
Unpaid Principal Balance	21,698	13,411
Related Valuation Allowance	0	0
Non-owner occupied | Commercial | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	25,925	29,245
Unpaid Principal Balance	27,514	30,863
Related Valuation Allowance	392	462
Vacant land | Commercial | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,000	1,008
Unpaid Principal Balance	1,205	1,208
Related Valuation Allowance	110	96
Vacant land | Commercial | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,648	2,825
Unpaid Principal Balance	2,635	3,911
Related Valuation Allowance	0	0
Vacant land | Commercial | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	2,648	3,833
Unpaid Principal Balance	3,840	5,119
Related Valuation Allowance	$ 110	$ 96