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		6 Months Ended
	Jun. 30, 2017 USD ($) Contract	Jun. 30, 2016 USD ($) Contract	Jun. 30, 2017 USD ($) Contract	Jun. 30, 2016 USD ($) Contract
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	10	8	18	10
Pre-Modification Outstanding Recorded Investment	$ 1,078	$ 685	$ 1,753	$ 756
Post-Modification Outstanding Recorded Investment	$ 1,083	$ 685	$ 1,746	$ 756
Secured by 1-4 Family Residential Properties [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	9	6	16	8
Pre-Modification Outstanding Recorded Investment	$ 834	$ 669	$ 1,168	$ 740
Post-Modification Outstanding Recorded Investment	$ 839	$ 669	$ 1,177	$ 740
Construction, Land Development and Other Land Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		1	1	1
Pre-Modification Outstanding Recorded Investment		$ 14	$ 341	$ 14
Post-Modification Outstanding Recorded Investment		$ 14	$ 325	$ 14
Commercial and Industrial Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract	1		1
Pre-Modification Outstanding Recorded Investment	$ 244		$ 244
Post-Modification Outstanding Recorded Investment	$ 244		$ 244
Consumer Loans [Member]
Troubled Debt Restructurings [Abstract]
Number of Contracts | Contract		1		1
Pre-Modification Outstanding Recorded Investment		$ 2		$ 2
Post-Modification Outstanding Recorded Investment		$ 2		$ 2