Loans and Allowance for Loan Leases - Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Recorded Balance
Total	$ 121,614	$ 93,500
Unpaid Principal Balance
Total	145,680	101,500
Specific Allowance	9,533	22,298
Interest Income Recognized
Total	3,557	3,212
Commercial
Recorded Balance
Loans without a specific valuation	36,111	35,846
Loans with a specific valuation	8,567	35,030
Total	44,678	70,876
Unpaid Principal Balance
Loans without a specific valuation	50,245	35,846
Loans with a specific valuation	8,567	40,030
Total	58,812	75,876
Specific Allowance	1,115	19,942
Average Investment Impaired Loans
Loans without a specific valuation	29,591	44,646
Loans with a specific valuation	8,637	39,688
Total	38,228	84,334
Interest Income Recognized
Loans without a specific valuation	1,143	1,549
Loans with a specific valuation	249	460
Total	1,392	2,009
Energy
Recorded Balance
Loans without a specific valuation	3,864	2,864
Loans with a specific valuation	22,181	6,880
Total	26,045	9,744
Unpaid Principal Balance
Loans without a specific valuation	6,677	2,864
Loans with a specific valuation	27,460	9,880
Total	34,137	12,744
Specific Allowance	3,370	1,949
Average Investment Impaired Loans
Loans without a specific valuation	6,710	4,381
Loans with a specific valuation	23,823	10,547
Total	30,533	14,928
Interest Income Recognized
Loans without a specific valuation	53	199
Loans with a specific valuation	542	264
Total	595	463
Commercial real estate
Recorded Balance
Loans without a specific valuation	10,079	9,464
Loans with a specific valuation	34,239	1,028
Total	44,318	10,492
Unpaid Principal Balance
Loans without a specific valuation	11,663	9,464
Loans with a specific valuation	34,239	1,028
Total	45,902	10,492
Specific Allowance	5,048	210
Average Investment Impaired Loans
Loans without a specific valuation	11,952	12,907
Loans with a specific valuation	27,980	1,037
Total	39,932	13,944
Interest Income Recognized
Loans without a specific valuation	390	669
Loans with a specific valuation	1,035	47
Total	1,425	716
Construction and land development
Recorded Balance
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Unpaid Principal Balance
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Specific Allowance	0	0
Average Investment Impaired Loans
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Interest Income Recognized
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Residential and multifamily real estate
Recorded Balance
Loans without a specific valuation	6,329	2,139
Loans with a specific valuation	0	249
Total	6,329	2,388
Unpaid Principal Balance
Loans without a specific valuation	6,585	2,139
Loans with a specific valuation	0	249
Total	6,585	2,388
Specific Allowance	0	197
Average Investment Impaired Loans
Loans without a specific valuation	6,315	2,140
Loans with a specific valuation	0	249
Total	6,315	2,389
Interest Income Recognized
Loans without a specific valuation	145	14
Loans with a specific valuation	0	10
Total	145	24
Paycheck Protection Program ("PPP")
Recorded Balance
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Unpaid Principal Balance
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Specific Allowance	0	0
Average Investment Impaired Loans
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Interest Income Recognized
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	0	0
Consumer
Recorded Balance
Loans without a specific valuation	244	0
Loans with a specific valuation	0	0
Total	244	0
Unpaid Principal Balance
Loans without a specific valuation	244	0
Loans with a specific valuation	0	0
Total	244	0
Specific Allowance	0	0
Average Investment Impaired Loans
Loans without a specific valuation	250	0
Loans with a specific valuation	0	0
Total	250	0
Interest Income Recognized
Loans without a specific valuation	0	0
Loans with a specific valuation	0	0
Total	$ 0	$ 0