Loans and Allowance for Credit Losses - Allowance for Credit Losses Based on Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance	$ 55,418	$ 32,876	$ 41,910	$ 26,911	$ 26,911
Initial allowance on loans purchased with credit deterioration	0		2,074
Provision for credit loss expense	(560)	6,136	11,576	11,617	16,103
Loans charged off	449	963	1,417	2,386	3,844
Recoveries collected	188	332	454	567	1,068
Allowance for credit losses, Ending Balance	54,597	38,381	54,597	38,381	41,910
Cumulative Change in Accounting Principal, Adjustment \| ASU 2016-13
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance				1,672	1,672
Construction and Land Development \| Real Estate Loan
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance	2,286	1,620	1,666	1,146	1,146
Initial allowance on loans purchased with credit deterioration	0		261
Provision for credit loss expense	(468)	738	(109)	1,325	646
Loans charged off	23	0	23	0	13
Recoveries collected	0	0	0	0	0
Allowance for credit losses, Ending Balance	1,795	2,358	1,795	2,358	1,666
Construction and Land Development \| Real Estate Loan \| Cumulative Change in Accounting Principal, Adjustment \| ASU 2016-13
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance				(113)	(113)
Agricultural \| Real Estate Loan
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance	1,628	1,335	1,084	1,093	1,093
Initial allowance on loans purchased with credit deterioration	0		44
Provision for credit loss expense	37	299	535	311	(239)
Loans charged off	0	0	0	0	0
Recoveries collected	0	0	2	0	0
Allowance for credit losses, Ending Balance	1,665	1,634	1,665	1,634	1,084
Agricultural \| Real Estate Loan \| Cumulative Change in Accounting Principal, Adjustment \| ASU 2016-13
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance				230	230
Residential Properties \| Real Estate Loan \| 1-4 Family
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance	3,093	1,931	2,322	1,386	1,386
Initial allowance on loans purchased with credit deterioration	0		328
Provision for credit loss expense	(527)	483	90	406	274
Loans charged off	14	69	196	265	393
Recoveries collected	18	141	26	203	299
Allowance for credit losses, Ending Balance	2,570	2,486	2,570	2,486	2,322
Residential Properties \| Real Estate Loan \| 1-4 Family \| Cumulative Change in Accounting Principal, Adjustment \| ASU 2016-13
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance				756	756
Commercial \| Real Estate Loan
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance	25,737	13,621	19,660	11,198	11,198
Initial allowance on loans purchased with credit deterioration	0		646
Provision for credit loss expense	(86)	3,118	5,816	5,079	8,581
Loans charged off	0	467	480	551	829
Recoveries collected	13	0	22	5	169
Allowance for credit losses, Ending Balance	25,664	16,272	25,664	16,272	19,660
Commercial \| Real Estate Loan \| Cumulative Change in Accounting Principal, Adjustment \| ASU 2016-13
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance				541	541
Agricultural Loans
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance	881	1,064	1,526	1,386	1,386
Initial allowance on loans purchased with credit deterioration	0		0
Provision for credit loss expense	24	259	(621)	300	503
Loans charged off	0	0	0	0	0
Recoveries collected	1	0	1	0	0
Allowance for credit losses, Ending Balance	906	1,323	906	1,323	1,526
Agricultural Loans \| Cumulative Change in Accounting Principal, Adjustment \| ASU 2016-13
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance				(363)	(363)
Commercial and Industrial Loans
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance	18,954	11,294	13,485	9,273	9,273
Initial allowance on loans purchased with credit deterioration	0		795
Provision for credit loss expense	934	1,286	5,608	4,101	5,869
Loans charged off	68	311	86	1,283	1,991
Recoveries collected	22	91	40	114	179
Allowance for credit losses, Ending Balance	19,842	12,360	19,842	12,360	13,485
Commercial and Industrial Loans \| Cumulative Change in Accounting Principal, Adjustment \| ASU 2016-13
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance				155	155
Consumer Loans
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance	2,839	2,011	2,167	1,429	1,429
Initial allowance on loans purchased with credit deterioration	0		0
Provision for credit loss expense	(474)	(47)	257	95	469
Loans charged off	344	116	632	287	618
Recoveries collected	134	100	363	245	421
Allowance for credit losses, Ending Balance	$ 2,155	$ 1,948	$ 2,155	1,948	2,167
Consumer Loans \| Cumulative Change in Accounting Principal, Adjustment \| ASU 2016-13
Allowance for loan losses [Abstract]
Allowance for credit losses, Beginning Balance				$ 466	$ 466

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Amount of increase in allowance for credit loss on financing receivable purchased with credit deterioration.

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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