Allowance for Loan Losses - Schedule of Loan Portfolio, Excluding PCI Loans and Related Allowance (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Recorded Investment
Individually Evaluated for Impairment	$ 38,085	$ 30,291
Collectively Evaluated for Impairment	4,008,187	3,769,670
Total	4,046,272	3,799,961
Associated Allowance
Individually Evaluated for Impairment	6,138	2,402
Collectively Evaluated for Impairment	27,727	24,720
Total	33,865	27,122
PCI Loans
Recorded Investment
Individually Evaluated for Impairment	13,051	17,417
Associated Allowance
Individually Evaluated for Impairment	0	0
Real Estate \| Construction and land development
Recorded Investment
Individually Evaluated for Impairment	412	474
Collectively Evaluated for Impairment	375,716	341,530
Total	376,128	342,004
Associated Allowance
Individually Evaluated for Impairment	23	23
Collectively Evaluated for Impairment	2,046	1,619
Total	2,069	1,642
Real Estate \| Construction and land development \| PCI Loans
Recorded Investment
Individually Evaluated for Impairment	129	1,121
Associated Allowance
Individually Evaluated for Impairment	0	0
Real Estate \| Commercial real estate
Recorded Investment
Individually Evaluated for Impairment	15,794	8,255
Collectively Evaluated for Impairment	1,699,743	1,621,960
Total	1,715,537	1,630,215
Associated Allowance
Individually Evaluated for Impairment	3,591	195
Collectively Evaluated for Impairment	9,727	9,090
Total	13,318	9,285
Real Estate \| Commercial real estate \| PCI Loans
Recorded Investment
Individually Evaluated for Impairment	10,838	9,776
Associated Allowance
Individually Evaluated for Impairment	0	0
Real Estate \| Residential real estate
Recorded Investment
Individually Evaluated for Impairment	19,804	18,720
Collectively Evaluated for Impairment	1,131,519	1,014,465
Total	1,151,323	1,033,185
Associated Allowance
Individually Evaluated for Impairment	869	1,091
Collectively Evaluated for Impairment	6,776	6,040
Total	7,645	7,131
Real Estate \| Residential real estate \| PCI Loans
Recorded Investment
Individually Evaluated for Impairment	1,356	5,626
Associated Allowance
Individually Evaluated for Impairment	0	0
Commercial and financial \| Commercial and financial
Recorded Investment
Individually Evaluated for Impairment	1,629	2,455
Collectively Evaluated for Impairment	608,598	602,666
Total	610,227	605,121
Associated Allowance
Individually Evaluated for Impairment	1,483	1,050
Collectively Evaluated for Impairment	6,679	6,247
Total	8,162	7,297
Commercial and financial \| Commercial and financial \| PCI Loans
Recorded Investment
Individually Evaluated for Impairment	728	894
Associated Allowance
Individually Evaluated for Impairment	0	0
Consumer \| Consumer
Recorded Investment
Individually Evaluated for Impairment	446	387
Collectively Evaluated for Impairment	192,611	189,049
Total	193,057	189,436
Associated Allowance
Individually Evaluated for Impairment	172	43
Collectively Evaluated for Impairment	2,499	1,724
Total	2,671	1,767
Consumer \| Consumer \| PCI Loans
Recorded Investment
Individually Evaluated for Impairment	0	0
Associated Allowance
Individually Evaluated for Impairment	$ 0	$ 0

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A valuation allowance for financing receivables that are expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively 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
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-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

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

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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The balance of financing receivables that were collectively evaluated for impairment.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 310
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The balance of financing receivables that were individually evaluated for impairment.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

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