Summary of Significant Accounting Policies - Narrative (Details)		12 Months Ended
	Jan. 01, 2021 USD ($)	Dec. 31, 2020 USD ($) trust segment large_borrower shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)
Accounting Policy [Line Items]
Number of wholly-owned Trusts | trust		1
Number of operating business lines | segment		2
Maturity period of securities at acquisition		90 days
Threshold for nonperforming loans individually evaluated for impairment		$ 50,000
Loan loss history used		5 years
Average holding of purchased receivables		1 year
Advertising, promotion and marketing expenses		$ 2,320,000	$ 2,373,000	$ 2,318,000
Anti-dilutive shares (in shares) | shares		45,062	0	44,721
Commercial and construction loans		$ 898,800,000	$ 513,300,000
PPP loans		$ 1,455,785,000	1,048,456,000
Large borrowing relationships | large_borrower		35
Unfunded commitments to large borrowers		$ 137,900,000
Increase (decrease) in equity from adoption of accounting standard		221,575,000	207,117,000	$ 205,947,000	$ 192,802,000
Reserve for unfunded loan commitments and letters of credit		187,000	152,000
Allowance for loan losses		21,136,000	19,088,000	19,519,000	21,461,000
Forecast
Accounting Policy [Line Items]
Expected credit loss, percentage calculated using the discounted cash flow method	97.00%
Allowance for loan losses	$ 16,600,000
Reserve for unfunded loan commitments and letters of credit	1,400,000
Cumulative effect, period of adoption, adjustment
Accounting Policy [Line Items]
Increase (decrease) in equity from adoption of accounting standard			0
Cumulative effect, period of adoption, adjustment | Forecast
Accounting Policy [Line Items]
Allowance for loan losses	(4,500,000)
Reserve for unfunded loan commitments and letters of credit	1,200,000
Cumulative effect, period of adoption, allowance for loan losses adjustment | Forecast
Accounting Policy [Line Items]
Increase (decrease) in equity from adoption of accounting standard	(3,200,000)
Cumulative effect, period of adoption, reserve for unfunded commitments adjustment | Forecast
Accounting Policy [Line Items]
Increase (decrease) in equity from adoption of accounting standard	$ 880,000
Retained Earnings
Accounting Policy [Line Items]
Increase (decrease) in equity from adoption of accounting standard		$ 173,498,000	149,615,000	137,452,000	124,407,000
Retained Earnings | Cumulative effect, period of adoption, adjustment
Accounting Policy [Line Items]
Increase (decrease) in equity from adoption of accounting standard			(139,000)
Lender Concentration Risk
Accounting Policy [Line Items]
Concentration risk, percent		43.00%
Commercial
Accounting Policy [Line Items]
PPP loans		$ 780,058,000	412,690,000
Allowance for loan losses		7,973,000	$ 6,604,000	$ 5,660,000	$ 6,172,000
Commercial | PPP Loans
Accounting Policy [Line Items]
PPP loans		$ 310,500,000
Buildings
Accounting Policy [Line Items]
Useful Life		39 years
Minimum | Furniture and equipment
Accounting Policy [Line Items]
Useful Life		3 years
Minimum | Leasehold improvements
Accounting Policy [Line Items]
Useful Life		2 years
Maximum | Furniture and equipment
Accounting Policy [Line Items]
Useful Life		7 years
Maximum | Leasehold improvements
Accounting Policy [Line Items]
Useful Life		15 years