LHFI and Allowance for Loan Losses, LHFI - Troubled Debt Restructuring Related to Loans Held for Investment, Excluding Covered Loans, by Loan Type (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable Modifications [Line Items]
Nonaccrual	$ 67,575	$ 49,234
Construction, Land Development and Other Land [Member] \| Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	2,105	3,323
Secured by 1-4 Family Residential Properties [Member] \| Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	19,022	20,329
Secured by Nonfarm, Nonresidential Properties [Member] \| Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	12,608	8,482
Other Real Estate Secured [Member] \| Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	212	402
Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	33,338	15,824
Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	135	300
Other Loans [Member]
Financing Receivable Modifications [Line Items]
Nonaccrual	155	574
Troubled Debt Restructurings [Member]
Financing Receivable Modifications [Line Items]
Accruing	660	53	$ 2,235
Nonaccrual	23,211	14,427	7,418
Total	23,871	14,480	9,653
Troubled Debt Restructurings [Member] \| Construction, Land Development and Other Land [Member] \| Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0	0
Nonaccrual	199	405	869
Total	199	405	869
Troubled Debt Restructurings [Member] \| Secured by 1-4 Family Residential Properties [Member] \| Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	51	0	1,426
Nonaccrual	3,140	2,873	2,424
Total	3,191	2,873	3,850
Troubled Debt Restructurings [Member] \| Secured by Nonfarm, Nonresidential Properties [Member] \| Loans Secured by Real Estate [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0	809
Nonaccrual	421	881	3,662
Total	421	881	4,471
Troubled Debt Restructurings [Member] \| Commercial and Industrial Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	53	53	0
Nonaccrual	19,434	10,266	463
Total	19,487	10,319	$ 463
Troubled Debt Restructurings [Member] \| Consumer Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	0	0
Nonaccrual	17	2
Total	17	$ 2
Troubled Debt Restructurings [Member] \| Other Loans [Member]
Financing Receivable Modifications [Line Items]
Accruing	556
Nonaccrual	0
Total	$ 556

Recorded investment in TDR's that are still accruing.

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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.

+ Details

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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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