Fair Value - Quantitative Information about Level 3 Fair Value Measurements (Details) - Non-recurring basis - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value	$ 361	$ 783
Significant Unobservable Inputs (Level 3)
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value	361	783
Commercial
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value	242	165
Commercial | Significant Unobservable Inputs (Level 3)
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value	242	165
Real estate | Significant Unobservable Inputs (Level 3) | Market Approach
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value		419
Commercial | Commercial | Significant Unobservable Inputs (Level 3) | Market Approach
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value	$ 242	$ 165
Commercial | Commercial | Significant Unobservable Inputs (Level 3) | Market Approach | Minimum
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Discount adjustment for differences between comparable sales (as a percent)		1.00%
Commercial | Commercial | Significant Unobservable Inputs (Level 3) | Market Approach | Maximum
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Discount adjustment for differences between comparable sales (as a percent)	1.00%
Commercial | Real estate | Significant Unobservable Inputs (Level 3) | Market Approach | Minimum
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Discount adjustment for differences between comparable sales (as a percent)		0.00%
Commercial | Real estate | Significant Unobservable Inputs (Level 3) | Market Approach | Maximum
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Discount adjustment for differences between comparable sales (as a percent)		3.00%
Commercial | Real estate | Significant Unobservable Inputs (Level 3) | Market Approach | Weighted average
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Discount adjustment for differences between comparable sales (as a percent)		3.00%
Land and construction | Real estate
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value	$ 119	$ 199
Land and construction | Real estate | Significant Unobservable Inputs (Level 3)
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value	119	199
Land and construction | Real estate | Significant Unobservable Inputs (Level 3) | Market Approach
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value	$ 119	$ 199
Land and construction | Real estate | Significant Unobservable Inputs (Level 3) | Market Approach | Maximum
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Discount adjustment for differences between comparable sales (as a percent)	1.00%	1.00%
Land and construction | Foreclosed Assets | Significant Unobservable Inputs (Level 3) | Foreclosed assets - commercial | Market Approach | Maximum
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Discount adjustment for differences between comparable sales (as a percent)		2.00%
Land and construction | Foreclosed Assets | Significant Unobservable Inputs (Level 3) | Foreclosed assets - commercial | Market Approach | Weighted average
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Discount adjustment for differences between comparable sales (as a percent)		2.00%
Land and construction | Foreclosed Assets | Significant Unobservable Inputs (Level 3) | Foreclosed assets - land and construction | Market Approach
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value		$ 229
Land and construction | Foreclosed Assets | Significant Unobservable Inputs (Level 3) | Foreclosed assets - land and construction | Market Approach | Minimum
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Discount adjustment for differences between comparable sales (as a percent)		0.00%
CRE | Real estate
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value		$ 419
CRE | Real estate | Significant Unobservable Inputs (Level 3)
Quantitative information about level 3 fair value measurements for financial instruments measured at fair value on a non-recurring basis
Impaired loans - held-for-investment, Fair Value		$ 419