Securities - Narrative (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) security $ / shares shares	Dec. 31, 2019 USD ($) security	Dec. 31, 2018 USD ($)
Debt and Equity Securities, FV-NI [Line Items]
Private mortgage-backed security fair value	$ 1,000,000.0	$ 1,100,000
Other than temporary impairment losses	$ 0	$ 0
Number of securities in an unrealized loss position | security	69	54
Investment securities, pledged as collateral for public deposits	$ 630,303,000	$ 260,826,000
Proceeds from sales of securities available for sale	219,697,000	39,797,000	$ 0
Gains (losses) sales of securities available for sale	8,024,000	97,000	$ 0
FHLB stock and FRB stock, cost	23,526,000	33,380,000
FHLB, cost	5,855,000	15,789,000
FRB stock	$ 17,671,000	$ 17,591,000
Visa, Inc | Common Class B
Debt and Equity Securities, FV-NI [Line Items]
Stock owned (in shares) | shares	12,356
Carrying value of shares	$ 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