Fair Value of Financial Instruments Nonrecurring Basis (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017
Assets measured on nonrecurring basis
OREO	$ 134,000				$ 227,000				$ 134,000
Losses on impaired loans charged through allowance for loan losses	(7,277,000)	$ 4,728,000	$ 11,834,000	$ 16,969,000	1,136,000	$ 1,005,000	$ 626,000	$ (263,000)
Valuation Allowance for Impairment of Recognized Servicing Assets, Deductions for Aggregate Write-Downs									161,000
Servicing rights (b)(c)	2,486,000				2,742,000				2,486,000	$ 2,655,000	$ 2,305,000
Nonrecurring Basis | Level 3
Assets measured on nonrecurring basis
Impaired Financing Receivable, Fair Value Disclosure	0				29,100,000				0
OREO	134,000				227,000				134,000
Servicing rights (b)(c)	2,591,000				3,881,000				2,591,000
Nonrecurring Basis | Level 2
Assets measured on nonrecurring basis
Impaired Financing Receivable, Fair Value Disclosure	0				0				0
OREO	0				0				0
Servicing rights (b)(c)	0				0				0
Nonrecurring Basis | Level 1
Assets measured on nonrecurring basis
Impaired Financing Receivable, Fair Value Disclosure	0				0				0
OREO	0				0				0
Servicing rights (b)(c)	$ 0				$ 0				$ 0