Fair Value Measurements - Nonrecurring (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
Assets and liabilities measured at fair value
Valuation allowance	$ 2,600,000		$ 1,200,000
Valuation allowance		$ 8,600,000
Carrying value of other real estate owned	2,474,000	7,175,000	5,004,000	$ 8,371,000
OREO Valuation allowance	1,643,000	8,027,000	6,712,000	$ 8,208,000
Fair Value, Measurements, Nonrecurring [Member]
Assets and liabilities measured at fair value
Total	12,149,000		12,439,000
Fair Value, Measurements, Nonrecurring [Member] | Impaired Loans [Member]
Assets and liabilities measured at fair value
Total	9,675,000		7,435,000
Valuation allowance	12,300,000
Increase (decrease) of specific allocations within the provision for loan losses	1,400,000	(783,000)
Fair Value, Measurements, Nonrecurring [Member] | Other Real Estate Owned [Member]
Assets and liabilities measured at fair value
Total	2,474,000		5,004,000
Carrying value of other real estate owned	2,500,000	5,000,000.0
Outstanding balance	4,100,000	12,600,000
OREO Valuation allowance	1,600,000	6,700,000
OREO participations		$ 937,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets and liabilities measured at fair value
Total	12,149,000		12,439,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Impaired Loans [Member]
Assets and liabilities measured at fair value
Total	9,675,000		7,435,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other Real Estate Owned [Member]
Assets and liabilities measured at fair value
Total	$ 2,474,000		$ 5,004,000