Basis of Accounting and Consolidation - Schedule of Impact of ASU 2016-13 Adoption (Details) - USD ($)	Sep. 30, 2020	Jun. 30, 2020	Jan. 01, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans	$ 41,915,000	$ 38,381,000		$ 26,911,000	$ 26,741,000	$ 26,359,000	$ 26,189,000
Pre-ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans				26,911,000
Allowance for credit losses on off-balance sheet exposures				0
ASU 2016-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			$ 28,583,000
Allowance for credit losses on off-balance sheet exposures			69,000
ASU 2016-13 | Impact of ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			1,672,000
Allowance for credit losses on off-balance sheet exposures			69,000
Construction & Land Development | Pre-ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans				1,146,000
Construction & Land Development | ASU 2016-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			1,033,000
Construction & Land Development | ASU 2016-13 | Impact of ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			(113,000)
Farm | Pre-ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans				1,093,000
Farm | ASU 2016-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			1,323,000
Farm | ASU 2016-13 | Impact of ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			230,000
1-4 Family Residential Properties | Pre-ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans				1,386,000
1-4 Family Residential Properties | ASU 2016-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			2,142,000
1-4 Family Residential Properties | ASU 2016-13 | Impact of ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			756,000
Commercial Real Estate | Pre-ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans				11,198,000
Commercial Real Estate | ASU 2016-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			11,739,000
Commercial Real Estate | ASU 2016-13 | Impact of ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			541,000
Agricultural | Pre-ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans				1,386,000
Agricultural | ASU 2016-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			1,023,000
Agricultural | ASU 2016-13 | Impact of ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			(363,000)
Commercial & Industrial | Pre-ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans				9,273,000
Commercial & Industrial | ASU 2016-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			9,428,000
Commercial & Industrial | ASU 2016-13 | Impact of ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			155,000
Consumer | Pre-ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans				$ 1,429,000
Consumer | ASU 2016-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			1,895,000
Consumer | ASU 2016-13 | Impact of ASU
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Allowance for credit losses on loans			$ 466,000