LHFI and Allowance for Loan Losses, LHFI - Impact of Modifications Classified as Troubled Debt Restructurings (Details) - Troubled Debt Restructurings [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) Contract	Dec. 31, 2016 USD ($) Contract	Dec. 31, 2015 USD ($) Contract
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	33	27	18
Pre-Modification Outstanding Recorded Investment	$ 15,637	$ 12,162	$ 4,301
Post-Modification Outstanding Recorded Investment	$ 15,630	$ 12,106	$ 4,301
Secured by 1-4 Family Residential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	22	18	13
Pre-Modification Outstanding Recorded Investment	$ 1,478	$ 1,386	$ 688
Post-Modification Outstanding Recorded Investment	$ 1,487	$ 1,391	$ 688
Construction, Land Development and Other Land [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	1	1
Pre-Modification Outstanding Recorded Investment	$ 341	$ 14
Post-Modification Outstanding Recorded Investment	$ 325	$ 14
Secured by Nonfarm, Nonresidential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	1	2	5
Pre-Modification Outstanding Recorded Investment	$ 426	$ 717	$ 3,613
Post-Modification Outstanding Recorded Investment	$ 426	$ 717	$ 3,613
Commercial and Industrial Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	8	5
Pre-Modification Outstanding Recorded Investment	$ 12,836	$ 10,043
Post-Modification Outstanding Recorded Investment	$ 12,836	$ 9,982
Other Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	1
Pre-Modification Outstanding Recorded Investment	$ 556
Post-Modification Outstanding Recorded Investment	$ 556
Consumer Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		1
Pre-Modification Outstanding Recorded Investment		$ 2
Post-Modification Outstanding Recorded Investment		$ 2