Loans and Allowance for Loan Losses - Impaired Loans (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Recorded Balance
Total	$ 45,502	$ 93,500
Unpaid Principal Balance
Total	66,254	101,500
Specific Allowance	6,992	22,298
Commercial
Recorded Balance
Loans without a specific valuation	70	35,846
Loans with a specific valuation	11,761	35,030
Total	11,831	70,876
Unpaid Principal Balance
Loans without a specific valuation	70	35,846
Loans with a specific valuation	29,710	40,030
Total	29,780	75,876
Specific Allowance	2,933	19,942
Energy
Recorded Balance
Loans without a specific valuation	0	2,864
Loans with a specific valuation	15,532	6,880
Total	15,532	9,744
Unpaid Principal Balance
Loans without a specific valuation	0	2,864
Loans with a specific valuation	18,244	9,880
Total	18,244	12,744
Specific Allowance	1,942	1,949
Commercial real estate
Recorded Balance
Loans without a specific valuation	763	9,464
Loans with a specific valuation	10,146	1,028
Total	10,909	10,492
Unpaid Principal Balance
Loans without a specific valuation	854	9,464
Loans with a specific valuation	10,146	1,028
Total	11,000	10,492
Specific Allowance	1,704	210
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
Residential real estate
Recorded Balance
Loans without a specific valuation	5,404	2,139
Loans with a specific valuation	1,577	249
Total	6,981	2,388
Unpaid Principal Balance
Loans without a specific valuation	5,404	2,139
Loans with a specific valuation	1,577	249
Total	6,981	2,388
Specific Allowance	413	197
Consumer
Recorded Balance
Loans without a specific valuation	249	0
Loans with a specific valuation	0	0
Total	249	0
Unpaid Principal Balance
Loans without a specific valuation	249	0
Loans with a specific valuation	0	0
Total	249	0
Specific Allowance	0	0
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