LHFI and Allowance for Loan Losses, LHFI - Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	$ 60,387	$ 35,077
Total LHFI With No Related Allowance Recorded	42,674	19,440
Total LHFI With an Allowance Recorded	6,262	7,635
Total LHFI Carrying Amount	48,936	27,075
Related Allowance	1,743	3,260
Average Recorded Investment	38,005	29,140
Commercial and Industrial Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	36,874	14,593
Total LHFI With No Related Allowance Recorded	31,281	11,222
Total LHFI With an Allowance Recorded	518	2,447
Total LHFI Carrying Amount	31,799	13,669
Related Allowance	131	1,976
Average Recorded Investment	22,734	14,258
Consumer Loans [Member]
Loan and Lease Receivables, Impaired [Abstract]
Total LHFI Unpaid Principal Balance	17	2
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	17	2
Total LHFI Carrying Amount	17	2
Related Allowance	0	0
Average Recorded Investment	9	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	556	95
Total LHFI With No Related Allowance Recorded	0	0
Total LHFI With an Allowance Recorded	556	95
Total LHFI Carrying Amount	556	95
Related Allowance	41	0
Average Recorded Investment	325	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	1,704	5,691
Total LHFI With No Related Allowance Recorded	1,206	2,213
Total LHFI With an Allowance Recorded	199	228
Total LHFI Carrying Amount	1,405	2,441
Related Allowance	75	103
Average Recorded Investment	1,923	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	6,031	6,134
Total LHFI With No Related Allowance Recorded	160	221
Total LHFI With an Allowance Recorded	4,576	4,428
Total LHFI Carrying Amount	4,736	4,649
Related Allowance	1,331	960
Average Recorded Investment	4,693	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	15,205	8,562
Total LHFI With No Related Allowance Recorded	10,027	5,784
Total LHFI With an Allowance Recorded	396	435
Total LHFI Carrying Amount	10,423	6,219
Related Allowance	165	221
Average Recorded Investment	8,321	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=84173941&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=84173941&loc=d3e5258-111524

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+ 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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