Fair Value Measurements - Nonrecurring (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Assets and liabilities measured at fair value
Carrying value of other real estate owned	$ 2,686,000	$ 5,004,000	$ 4,682,000	$ 7,175,000
Outstanding balance		12,700,000
OREO Valuation allowance	1,613,000	6,712,000	$ 7,466,000	$ 8,027,000
Impaired Loans [Member]
Assets and liabilities measured at fair value
Valuation allowance		8,600,000
Other Real Estate Owned [Member]
Assets and liabilities measured at fair value
Outstanding balance		12,700,000
Fair Value, Measurements, Nonrecurring [Member]
Assets and liabilities measured at fair value
Total	14,886,000	12,439,000
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans [Member]
Assets and liabilities measured at fair value
Total	12,200,000	7,435,000
Valuation allowance	2,700,000	1,200,000
Increase (decrease) of specific allocations within the provision for loan losses	1,600,000	783,000
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans [Member] | Reported Value Measurement [Member]
Assets and liabilities measured at fair value
Total	14,900,000
Fair Value, Measurements, Nonrecurring [Member] | Other Real Estate Owned [Member]
Assets and liabilities measured at fair value
Total	2,686,000	5,004,000
Carrying value of other real estate owned	2,700,000	5,000,000.0
Outstanding balance	4,300,000
OREO Valuation allowance	1,600,000	6,700,000
OREO participations		937,000
Fair Value, Measurements, Nonrecurring [Member] | Level 3
Assets and liabilities measured at fair value
Total	14,886,000	12,439,000
Fair Value, Measurements, Nonrecurring [Member] | Level 3 | Impaired Loans [Member]
Assets and liabilities measured at fair value
Total	12,200,000	7,435,000
Fair Value, Measurements, Nonrecurring [Member] | Level 3 | Other Real Estate Owned [Member]
Assets and liabilities measured at fair value
Total	$ 2,686,000	$ 5,004,000