Loans and Allowance for Loan Losses - Credit Risk Profile of Loan Portfolio on Amortized Cost Basis Based on Risk Rating Category (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Credit Quality Information [Abstract]
2020	$ 986,624
2019	586,488
2018	412,756
2017	340,713
2016	289,752
Prior	587,961
Revolving Loans	31,953
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	3,236,247	$ 2,695,347
Pass
Credit Quality Information [Abstract]
2020	958,706
2019	541,886
2018	395,462
2017	330,776
2016	275,065
Prior	543,021
Revolving Loans	30,391
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	3,075,307	2,558,157
Special Mention
Credit Quality Information [Abstract]
2020	24,749
2019	40,863
2018	12,487
2017	2,879
2016	7,763
Prior	16,798
Revolving Loans	310
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	105,849	71,611
Substandard
Credit Quality Information [Abstract]
2020	3,169
2019	3,739
2018	4,807
2017	7,058
2016	6,924
Prior	28,142
Revolving Loans	1,252
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	55,091	65,579
Agricultural Loans
Credit Quality Information [Abstract]
2020	96,923
2019	29,917
2018	7,855
2017	2,494
2016	1,007
Prior	2,878
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	141,074	136,124
Agricultural Loans | Pass
Credit Quality Information [Abstract]
2020	77,482
2019	24,639
2018	7,235
2017	2,487
2016	800
Prior	2,856
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	115,499	129,811
Agricultural Loans | Special Mention
Credit Quality Information [Abstract]
2020	18,818
2019	5,237
2018	595
2017	7
2016	207
Prior	22
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	24,886	3,862
Agricultural Loans | Substandard
Credit Quality Information [Abstract]
2020	623
2019	41
2018	25
2017	0
2016	0
Prior	0
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	689	2,451
Commercial and Industrial Loans
Credit Quality Information [Abstract]
2020	431,194
2019	169,174
2018	76,734
2017	81,948
2016	46,212
Prior	129,820
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	935,082	655,580
Commercial and Industrial Loans | Pass
Credit Quality Information [Abstract]
2020	427,402
2019	134,753
2018	76,051
2017	80,506
2016	45,685
Prior	127,547
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	891,944	603,047
Commercial and Industrial Loans | Special Mention
Credit Quality Information [Abstract]
2020	2,790
2019	31,962
2018	189
2017	141
2016	343
Prior	1,111
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	36,536	40,395
Commercial and Industrial Loans | Substandard
Credit Quality Information [Abstract]
2020	1,002
2019	2,459
2018	494
2017	1,301
2016	184
Prior	1,162
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	6,602	12,138
Consumer Loans
Credit Quality Information [Abstract]
2020	26,072
2019	24,452
2018	14,238
2017	9,902
2016	4,044
Prior	1,640
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	80,348	83,183
Consumer Loans | Pass
Credit Quality Information [Abstract]
2020	26,068
2019	24,420
2018	14,086
2017	9,794
2016	3,014
Prior	332
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	77,714	82,117
Consumer Loans | Special Mention
Credit Quality Information [Abstract]
2020	4
2019	0
2018	39
2017	1
2016	949
Prior	1,172
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	2,165	140
Consumer Loans | Substandard
Credit Quality Information [Abstract]
2020	0
2019	32
2018	113
2017	107
2016	81
Prior	136
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	469	926
Real Estate Loan
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	2,079,743	1,820,460
Real Estate Loan | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		1,743,182
Real Estate Loan | Special Mention
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		27,214
Real Estate Loan | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		50,064
Real Estate Loan | Construction and Land Development
Credit Quality Information [Abstract]
2020	61,198
2019	67,874
2018	29,449
2017	3,329
2016	1,041
Prior	4,624
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	167,515	94,142
Real Estate Loan | Construction and Land Development | Pass
Credit Quality Information [Abstract]
2020	61,198
2019	67,437
2018	29,449
2017	2,805
2016	1,041
Prior	4,571
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	166,501	93,413
Real Estate Loan | Construction and Land Development | Special Mention
Credit Quality Information [Abstract]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0	413
Real Estate Loan | Construction and Land Development | Substandard
Credit Quality Information [Abstract]
2020	0
2019	437
2018	0
2017	524
2016	0
Prior	53
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,014	316
Real Estate Loan | Agricultural
Credit Quality Information [Abstract]
2020	63,279
2019	39,645
2018	42,585
2017	17,564
2016	15,871
Prior	77,286
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	256,230	240,241
Real Estate Loan | Agricultural | Pass
Credit Quality Information [Abstract]
2020	62,248
2019	36,161
2018	41,540
2017	17,210
2016	14,940
Prior	66,631
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	238,730	231,227
Real Estate Loan | Agricultural | Special Mention
Credit Quality Information [Abstract]
2020	1,031
2019	3,484
2018	558
2017	140
2016	874
Prior	10,408
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	16,495	6,902
Real Estate Loan | Agricultural | Substandard
Credit Quality Information [Abstract]
2020	0
2019	0
2018	487
2017	214
2016	57
Prior	247
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,005	2,112
Real Estate Loan | Commercial
Credit Quality Information [Abstract]
2020	240,088
2019	220,546
2018	198,261
2017	194,236
2016	187,263
Prior	276,432
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,316,826	1,149,650
Real Estate Loan | Commercial | Pass
Credit Quality Information [Abstract]
2020	236,928
2019	220,454
2018	185,898
2017	189,533
2016	177,598
Prior	255,195
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,265,606	1,103,543
Real Estate Loan | Commercial | Special Mention
Credit Quality Information [Abstract]
2020	1,910
2019	22
2018	10,785
2017	1,637
2016	5,141
Prior	2,909
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	22,404	14,156
Real Estate Loan | Commercial | Substandard
Credit Quality Information [Abstract]
2020	1,250
2019	70
2018	1,578
2017	3,066
2016	4,524
Prior	18,328
Revolving Loans	0
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	28,816	31,951
1-4 Family | Real Estate Loan | Residential Properties
Credit Quality Information [Abstract]
2020	67,870
2019	34,880
2018	43,634
2017	31,240
2016	34,314
Prior	95,281
Revolving Loans	31,953
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	339,172	336,427
1-4 Family | Real Estate Loan | Residential Properties | Pass
Credit Quality Information [Abstract]
2020	67,380
2019	34,022
2018	41,203
2017	28,441
2016	31,987
Prior	85,889
Revolving Loans	30,391
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	319,313	314,999
1-4 Family | Real Estate Loan | Residential Properties | Special Mention
Credit Quality Information [Abstract]
2020	196
2019	158
2018	321
2017	953
2016	249
Prior	1,176
Revolving Loans	310
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	3,363	5,743
1-4 Family | Real Estate Loan | Residential Properties | Substandard
Credit Quality Information [Abstract]
2020	294
2019	700
2018	2,110
2017	1,846
2016	2,078
Prior	8,216
Revolving Loans	1,252
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	$ 16,496	$ 15,685