Loans - Impaired Loans by Class (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	$ 71,241	$ 74,740
Unpaid Principal Balance	79,380	85,264
Related Valuation Allowance	7,547	9,392
Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	34,889	32,129
Unpaid Principal Balance	40,872	38,794
Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	106,130	106,869
Unpaid Principal Balance	120,252	124,058
Related Valuation Allowance	7,547	9,392
Commercial | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	28,623	28,925
Unpaid Principal Balance	31,419	33,209
Related Valuation Allowance	4,335	3,128
Commercial | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	7,677	7,435
Unpaid Principal Balance	9,761	11,153
Commercial | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	36,300	36,360
Unpaid Principal Balance	41,180	44,362
Related Valuation Allowance	4,335	3,128
Commercial real estate | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	20,209	21,318
Unpaid Principal Balance	25,552	27,558
Related Valuation Allowance	1,334	2,102
Commercial real estate | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	21,512	20,588
Unpaid Principal Balance	25,411	23,535
Commercial real estate | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	41,721	41,906
Unpaid Principal Balance	50,963	51,093
Related Valuation Allowance	1,334	2,102
Real estate construction and land development | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	189	177
Unpaid Principal Balance	189	177
Related Valuation Allowance	4	4
Real estate construction and land development | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	56	80
Unpaid Principal Balance	56	80
Real estate construction and land development | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	245	257
Unpaid Principal Balance	245	257
Related Valuation Allowance	4	4
Residential mortgage | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	16,711	20,864
Unpaid Principal Balance	16,711	20,864
Related Valuation Allowance	724	3,528
Residential mortgage | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	4,386	3,252
Unpaid Principal Balance	4,386	3,252
Residential mortgage | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	21,097	24,116
Unpaid Principal Balance	21,097	24,116
Related Valuation Allowance	724	3,528
Consumer installment | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	851	879
Unpaid Principal Balance	851	879
Related Valuation Allowance	88	240
Consumer installment | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	851	879
Unpaid Principal Balance	851	879
Related Valuation Allowance	88	240
Home equity | Impaired loans with a valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	4,658	2,577
Unpaid Principal Balance	4,658	2,577
Related Valuation Allowance	1,062	390
Home equity | Impaired loans with no valuation allowance
Financing Receivable, Impaired [Line Items]
Recorded Investment	1,258	774
Unpaid Principal Balance	1,258	774
Home equity | Total Impaired Loans
Financing Receivable, Impaired [Line Items]
Recorded Investment	5,916	3,351
Unpaid Principal Balance	5,916	3,351
Related Valuation Allowance	$ 1,062	$ 390