Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI - Impact of Modifications Classified as Troubled Debt Restructurings (Details) - Troubled Debt Restructurings [Member] $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015 USD ($) Contract	Sep. 30, 2016 USD ($) Contract	Sep. 30, 2015 USD ($) Contract
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		10	14
Pre-Modification Outstanding Recorded Investment		$ 756	$ 4,007
Post-Modification Outstanding Recorded Investment		$ 756	$ 4,007
Construction, Land Development and Other Land Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		1
Pre-Modification Outstanding Recorded Investment		$ 14
Post-Modification Outstanding Recorded Investment		$ 14
Secured by Nonfarm, Nonresidential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract			4
Pre-Modification Outstanding Recorded Investment			$ 3,512
Post-Modification Outstanding Recorded Investment			$ 3,512
Consumer Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		1
Pre-Modification Outstanding Recorded Investment		$ 2
Post-Modification Outstanding Recorded Investment		$ 2
Secured by 1-4 Family Residential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	2	8	10
Pre-Modification Outstanding Recorded Investment	$ 35	$ 740	$ 495
Post-Modification Outstanding Recorded Investment	$ 35	$ 740	$ 495