Loans (Narrative) (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) loan	Mar. 31, 2020 USD ($) loan	Dec. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income on non-accrual loans	$ 2,000		$ 28,000
Troubled debt restructurings	109,000		111,000
Additional lending amount to customers whose loan terms has been modified in troubled debt restructuring	$ 0		0
Number of loans modified as troubled debt restructurings | loan	0	0
Number of loans modified as troubled debt restructuring subsequently defaulted | loan	0	0
Threshold amount to individually classify loans by credit risk	$ 250,000
PPP | Commercial and Industrial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan interest rate	1.00%
Maturities of loans originated under first round	2 years
Maturities of loans originated under second round	5 years
Loans outstanding originated under first round	$ 97,331,000
Remaining fees on loans originated under first round	1,232,000
Loans outstanding originated under second round	145,364,000
Fees remining on loans originated under second round	7,234,000
Loans outstanding			186,038,000
Remaining fees on loans outstanding			$ 4,054,000
Fees recognized	$ 3,008,000	$ 0