Short-Term Borrowings and Long-Term Debt (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt	$ 40,370,000	$ 20,436,000
Repayments of long-term debt	15,066,000	55,064,000	$ 20,061,000
Proceeds from Issuance of debt		10,000,000
Debt conversion, original debt, amount	40,400,000	20,400,000
Proceeds from Issuance of Long-term Debt	35,000,000	20,000,000	$ 10,000,000
Due in 2018	20,000,000
Due in 2022	5,000,000
Daily advances outstanding	0	0
Short-term advances	5,000,000	$ 35,000,000
Fixed Rate Advance Matures in 2020 [Member]
Debt Instrument [Line Items]
Repayments of long-term debt	10,000,000
Proceeds from Issuance of debt	$ 35,000,000
Interest rate	1.85%	2.81%
Fixed Rate Advance Matures in 2021 [Member]
Debt Instrument [Line Items]
Repayments of long-term debt	$ 3,000,000
Proceeds from Issuance of debt	$ 10,000,000
Interest rate	1.70%	2.92%
Fixed Rate Advance Matures in 2022 [Member]
Debt Instrument [Line Items]
Repayments of long-term debt	$ 2,000,000
Interest rate	1.69%
Fixed Rate Advance Matures in 2024 [Member]
Debt Instrument [Line Items]
Repayments of long-term debt	$ 5,000,000
Interest rate	1.67%
Fixed Rate Convertible [Member]
Debt Instrument [Line Items]
Long-term debt	$ 0
Due in 2018	0
Due in 2022	0
Letter of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility, fair value of amount outstanding	43,000,000
Federal Reserve Bank Of Richmond [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	7,734,000	$ 5,700,000
Amount outstanding	0	0
Other Commercial Banks [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	32,000,000	22,000,000
Amount outstanding	0	0
Credit Facility With Commercial Bank [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		40,000,000
Amount outstanding	0	0
Federal Home Loan Bank Borrowings [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	369,800,000	380,500,000
Security owned and pledged as collateral, fair value	578,700,000	589,200,000
FHLB lendable collateral	458,100,000	466,000,000
FHLB lendable pledged collateral	304,600,000	298,600,000
Line of credit facility, current borrowing capacity	216,300,000	213,100,000
Line of credit facility, fair value of amount outstanding	45,400,000	55,400,000
FHLB lendable unpledged collateral	$ 153,500,000	167,400,000
Maximum
Debt Instrument [Line Items]
Initial period after which debt callable	5 years
Minimum
Debt Instrument [Line Items]
Initial period after which debt callable	6 months
Advances and Security Agreement [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 538,800,000	$ 506,200,000
Percentage of assets limited to maximum borrowing capacity	30.00%	30.00%