Loans - Summary of Portfolio Loans Individually Evaluated for Impairment by Category (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Related Allowance	$ 600
Portfolio loans, net
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	1,871
Unpaid Contractual Principal Balance	25,094	$ 24,343
Recorded Investment With No Allowance	5,255	4,856
Recorded Investment With Allowance	10,327	10,831
Total Recorded Investment	15,582	15,687
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,893	2,579
Impaired Financing Receivable, Related Allowance	2,893	2,579
Average Recorded Investment	16,775	19,722
Financing Receivable, Allowance for Credit Losses, Write-downs	(1,035)
Financing Receivable, Allowance for Credit Losses, Recovery	1,261
Financing Receivable, Allowance for Credit Losses	40,263	38,166
Portfolio loans, net \| Commercial and industrial
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	780
Unpaid Contractual Principal Balance	21,353	20,750
Recorded Investment With No Allowance	2,470	2,321
Recorded Investment With Allowance	9,843	10,344
Total Recorded Investment	12,313	12,665
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,794	2,508
Impaired Financing Receivable, Related Allowance	2,794	2,508
Average Recorded Investment	13,278	16,270
Financing Receivable, Allowance for Credit Losses, Write-downs	(732)
Financing Receivable, Allowance for Credit Losses, Recovery	956
Financing Receivable, Allowance for Credit Losses	27,410	26,406
Portfolio loans, net \| Commercial - investor owned
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	648
Unpaid Contractual Principal Balance	558	560
Recorded Investment With No Allowance	416	422
Recorded Investment With Allowance	0	0
Total Recorded Investment	416	422
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Impaired Financing Receivable, Related Allowance	0	0
Average Recorded Investment	418	521
Financing Receivable, Allowance for Credit Losses, Write-downs	0
Financing Receivable, Allowance for Credit Losses, Recovery	8
Financing Receivable, Allowance for Credit Losses	4,546	3,890
Portfolio loans, net \| Commercial - owner occupied
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	190
Unpaid Contractual Principal Balance	755	487
Recorded Investment With No Allowance	267	0
Recorded Investment With Allowance	484	487
Total Recorded Investment	751	487
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	99	71
Impaired Financing Receivable, Related Allowance	99	71
Average Recorded Investment	753	490
Financing Receivable, Allowance for Credit Losses, Write-downs	0
Financing Receivable, Allowance for Credit Losses, Recovery	4
Financing Receivable, Allowance for Credit Losses	3,502	3,308
Portfolio loans, net \| Construction and land development
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	35
Unpaid Contractual Principal Balance	0	441
Recorded Investment With No Allowance	0	136
Recorded Investment With Allowance	0	0
Total Recorded Investment	0	136
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Impaired Financing Receivable, Related Allowance	0	0
Average Recorded Investment	0	331
Financing Receivable, Allowance for Credit Losses, Write-downs	0
Financing Receivable, Allowance for Credit Losses, Recovery	206
Financing Receivable, Allowance for Credit Losses	1,728	1,487
Portfolio loans, net \| Residential real estate
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	259
Unpaid Contractual Principal Balance	2,103	1,730
Recorded Investment With No Allowance	1,777	1,602
Recorded Investment With Allowance	0	0
Total Recorded Investment	1,777	1,602
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Impaired Financing Receivable, Related Allowance	0	0
Average Recorded Investment	1,985	1,735
Financing Receivable, Allowance for Credit Losses, Write-downs	(254)
Financing Receivable, Allowance for Credit Losses, Recovery	73
Financing Receivable, Allowance for Credit Losses	2,315	2,237
Portfolio loans, net \| Consumer and other
Financing Receivable, Impaired [Line Items]
Provision for Loan, Lease, and Other Losses	(41)
Unpaid Contractual Principal Balance	325	375
Recorded Investment With No Allowance	325	375
Recorded Investment With Allowance	0	0
Total Recorded Investment	325	375
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Impaired Financing Receivable, Related Allowance	0	0
Average Recorded Investment	341	375
Financing Receivable, Allowance for Credit Losses, Write-downs	(49)
Financing Receivable, Allowance for Credit Losses, Recovery	14
Financing Receivable, Allowance for Credit Losses	$ 762	$ 838

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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