Loans and Allowance for Credit Losses - Average Recorded Investment and Interest Income Recognized on Impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	$ 30,938	$ 41,700	$ 38,618
Interest Income Recognized	66	448	619
Real Estate Loan
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	24,790	30,178	28,754
Interest Income Recognized	65	435	589
Construction and Land Development | Real Estate Loan
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	694	622	2,558
Interest Income Recognized	7	32	37
Farm Loans | Real Estate Loan
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	827	1,218	415
Interest Income Recognized	0	0	0
Residential Properties | Real Estate Loan | 1-4 Family
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	8,557	9,659	6,297
Interest Income Recognized	17	80	144
Residential Properties | Real Estate Loan | Multifamily
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	2,325	6,490	9,666
Interest Income Recognized	0	89	137
Commercial | Real Estate Loan
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	12,387	12,189	9,818
Interest Income Recognized	41	234	271
Agricultural Loans
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	815	808	727
Interest Income Recognized	0	3	23
Commercial and Industrial Loans
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	4,941	10,065	9,003
Interest Income Recognized	1	9	6
Consumer Loans
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	392	649	131
Interest Income Recognized	0	1	1
All Other Loans
Average recorded investment and interest income recognized [Abstract]
Average Investment in Impaired Loans	0	0	3
Interest Income Recognized	$ 0	$ 0	$ 0