Loans and Allowance for Losses (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs									$ 67,000	$ 17,000	$ 327,000
Change in total provision for losses									3,200,000	(1,400,000)
Troubled debt restructurings, recorded investment	$ 38,500,000								38,500,000
Past due financing receivables	60,954,000				$ 26,881,000				60,954,000	26,881,000
Loans subject to removal-of-account provisions	0				100,000				0	100,000
Provision for losses	2,430,000	$ 760,000	$ 578,000	$ (264,000)	146,000	$ 99,000	$ 424,000	$ (431,000)	3,504,000	238,000	1,708,000
Allowance for Loan Losses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs									67,000	17,000	327,000
Provision for losses									3,504,000	238,000	1,708,000
Reserve for Losses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Charge-offs									0	0	$ 0
On-Balance Sheet:
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due financing receivables	$ 57,719,000				$ 19,577,000				$ 57,719,000	$ 19,577,000