Loans - Summary of Recorded Investment in Impaired Portfolio Loans by Category (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Restructured, not on non-accrual	$ 8,100
Impaired Financing Receivable, Related Allowance	600
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	15,582	$ 15,687
Non-accrual	14,858	14,968
Restructured, not on non-accrual	724	719
Impaired Financing Receivable, Related Allowance	2,893	2,579
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,893	2,579
Non-Covered Loans \| Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	12,313	12,665
Non-accrual	11,589	11,946
Restructured, not on non-accrual	724	719
Impaired Financing Receivable, Related Allowance	2,794	2,508
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,794	2,508
Non-Covered Loans \| Commercial - investor owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	416	422
Non-accrual	416	422
Restructured, not on non-accrual	0	0
Impaired Financing Receivable, Related Allowance	0	0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Non-Covered Loans \| Commercial - owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	751	487
Non-accrual	751	487
Restructured, not on non-accrual	0	0
Impaired Financing Receivable, Related Allowance	99	71
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	99	71
Non-Covered Loans \| Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	0	136
Non-accrual	0	136
Restructured, not on non-accrual	0	0
Impaired Financing Receivable, Related Allowance	0	0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Non-Covered Loans \| Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	1,777	1,602
Non-accrual	1,777	1,602
Restructured, not on non-accrual	0	0
Impaired Financing Receivable, Related Allowance	0	0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0	0
Non-Covered Loans \| Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	325	375
Non-accrual	325	375
Restructured, not on non-accrual	0	0
Impaired Financing Receivable, Related Allowance	0	0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 0	$ 0

Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18845-111554

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- Definition

Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524

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- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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