Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2017	Dec. 31, 2016
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	$ 60,636	$ 35,077
Total LHFI With No Related Allowance Recorded	21,138	19,440
Total LHFI With an Allowance Recorded	32,247	7,635
Total LHFI Carrying Amount	53,385	27,075
Related Allowance	6,169	3,260
Average Recorded Investment	40,230	29,140
Commercial and Industrial Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	24,273	14,593
Total LHFI With No Related Allowance Recorded	11,293	11,222
Total LHFI With an Allowance Recorded	12,444	2,447
Total LHFI Carrying Amount	23,737	13,669
Related Allowance	1,652	1,976
Average Recorded Investment	18,703	14,258
Consumer Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	1	2
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	1	2
Total LHFI Carrying Amount	1	2
Related Allowance	0	0
Average Recorded Investment	1	2
State and Other Political Subdivision Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	0	0
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	0	0
Total LHFI Carrying Amount	0	0
Related Allowance	0	0
Average Recorded Investment	0	0
Other Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	4,523	95
Total LHFI With No Related Allowance Recorded	95	0
Total LHFI With an Allowance Recorded	4,428	95
Total LHFI Carrying Amount	4,523	95
Related Allowance	0	0
Average Recorded Investment	2,309	95
Loans Secured by Real Estate [Member] \| Construction, Land Development and Other Land [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	4,930	5,691
Total LHFI With No Related Allowance Recorded	1,645	2,213
Total LHFI With an Allowance Recorded	335	228
Total LHFI Carrying Amount	1,980	2,441
Related Allowance	112	103
Average Recorded Investment	2,210	2,943
Loans Secured by Real Estate [Member] \| Secured by 1-4 Family Residential Properties [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	6,646	6,134
Total LHFI With No Related Allowance Recorded	188	221
Total LHFI With an Allowance Recorded	5,072	4,428
Total LHFI Carrying Amount	5,260	4,649
Related Allowance	1,320	960
Average Recorded Investment	4,955	4,639
Loans Secured by Real Estate [Member] \| Secured by Nonfarm, Nonresidential Properties [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	20,263	8,562
Total LHFI With No Related Allowance Recorded	7,917	5,784
Total LHFI With an Allowance Recorded	9,967	435
Total LHFI Carrying Amount	17,884	6,219
Related Allowance	3,085	221
Average Recorded Investment	12,052	6,703
Loans Secured by Real Estate [Member] \| Other Real Estate Secured [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	0	0
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	0	0
Total LHFI Carrying Amount	0	0
Related Allowance	0	0
Average Recorded Investment	$ 0	$ 500

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5258-111524

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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=66008989&loc=SL6953550-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: 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=66008989&loc=d3e5212-111524

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