Allowance for Probable Loan Losses (Non-accrual Basis By Loan Class) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Loan loss allowances, financing receivable past due
Non-accrual loans, total	$ 12,150	$ 15,791
Commercial
Loan loss allowances, financing receivable past due
Non-accrual loans, total	7,379	9,143
Commercial Real Estate:Other Construction and Land Development
Loan loss allowances, financing receivable past due
Non-accrual loans, total	1,794	2,092
Commercial Real Estate: Farmland and Commercial
Loan loss allowances, financing receivable past due
Non-accrual loans, total	1,740	3,509
Commercial Real Estate: Multifamily
Loan loss allowances, financing receivable past due
Non-accrual loans, total	649	507
Residential First Lien
Loan loss allowances, financing receivable past due
Non-accrual loans, total	583	347
Residential Junior Lien
Loan loss allowances, financing receivable past due
Non-accrual loans, total		171
Consumer
Loan loss allowances, financing receivable past due
Non-accrual loans, total	$ 5	$ 22