Securities (Narrative) (Details) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Debt and Equity Securities, FV-NI [Line Items]
Private mortgage-backed security fair value	$ 1,000,000.0	$ 1,000,000.0		$ 1,000,000
Other than temporary impairment losses		0		0
Proceeds from sales of securities available for sale	39,797,000	39,797,000	$ 0
Debt Securities, Available-for-sale, Realized Gain (Loss)		97,000	$ 0
Investment securities, pledged as collateral for public deposits	287,418,000	287,418,000		234,382,000
FHLB stock and FRB stock, cost	33,380,000	33,380,000		37,468,000
FHLB, cost	15,789,000	15,789,000		20,036,000
FRB stock	$ 17,591,000	$ 17,591,000		$ 17,432,000
Visa, Inc | Common Class B
Debt and Equity Securities, FV-NI [Line Items]
Stock owned (in shares)	12,356	12,356
Visa, Inc | Common Class A
Debt and Equity Securities, FV-NI [Line Items]
Conversion price (in dollars per share)	$ 1.62	$ 1.62
Conversion of stock (in shares)		20,051