Securities (Narrative) (Details)	3 Months Ended
	Mar. 31, 2021 USD ($) security $ / shares shares	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) security
Debt and Equity Securities, FV-NI [Line Items]
Private mortgage-backed security fair value	$ 900,000		$ 1,000,000.0
Number of securities held in an unrealized loss position | security	161		69
Impairment charges on available for sale securities		$ 0
Impairment charges on held to maturity securities		$ 0
Investment securities, pledged as collateral for public deposits	$ 718,340,000		$ 630,303,000
FHLB stock and FRB stock, cost	21,690,000		23,526,000
FHLB, cost	3,970,000		5,855,000
FRB stock	$ 17,720,000		$ 17,671,000
Visa, Inc | Common Class B
Debt and Equity Securities, FV-NI [Line Items]
Stock owned (in shares) | shares	12,356
Investment without readily determinable fair value	$ 0
Visa, Inc | Common Class A
Debt and Equity Securities, FV-NI [Line Items]
Conversion price (in dollars per share) | $ / shares	$ 1.62
Conversion of stock (in shares) | shares	20,051