Loans - Summary of Recorded Investment in Impaired Portfolio Loans by Category (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($) loan	Sep. 30, 2017 loan	Sep. 30, 2018 USD ($) loan	Sep. 30, 2017 loan	Dec. 31, 2017 USD ($)
Financing Receivable, Recorded Investment, Past Due [Line Items]
Restructured, not on non-accrual	$ 8,000		$ 8,000
Impaired Financing Receivable, Related Allowance	200		200
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 17,044		$ 17,044		$ 15,687
Financing Receivable, Modifications, Number of Contracts \| loan	1	0	1	1
Non-accrual	$ 14,935		$ 14,935		14,968
Restructured, not on non-accrual	820		820		719
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	1,289		1,289
Impaired Financing Receivable, Related Allowance	4,314		4,314		2,579
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	4,314		4,314		2,579
Non-Covered Loans \| Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 12,197		$ 12,197		12,665
Financing Receivable, Modifications, Number of Contracts \| loan	1	0	1
Non-accrual	$ 10,088		$ 10,088		11,946
Restructured, not on non-accrual	820		820		719
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	1,289		1,289
Impaired Financing Receivable, Related Allowance	4,128		4,128		2,508
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	4,128		4,128		2,508
Non-Covered Loans \| Commercial - investor owned
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	770		770		422
Non-accrual	770		770		422
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	0		0		0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0		0
Non-Covered Loans \| Commercial - owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	1,288		1,288		487
Non-accrual	1,288		1,288		487
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	177		177		71
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	177		177		71
Non-Covered Loans \| Construction and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	0		0		136
Non-accrual	0		0		136
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	0		0		0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0		0
Non-Covered Loans \| Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	2,477		2,477		1,602
Non-accrual	2,477		2,477		1,602
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	9		9		0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	9		9		0
Non-Covered Loans \| Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Impaired Financing Receivable, Recorded Investment	312		312		375
Non-accrual	312		312		375
Restructured, not on non-accrual	0		0		0
Impaired Financing Receivables, Recorded Investment, 90 Days Past Due and Still Accruing	0		0
Impaired Financing Receivable, Related Allowance	0		0		0
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	$ 0		$ 0		$ 0

The balance of impaired financing receivables greater than 90 days past due that are still accruing interest.

No definition available.

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- Definition

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

+ References

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

Number of 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 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953676-111524

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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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