Loans - Additional Information (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($) payment	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) loan payment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Financing Receivable, Troubled Debt Restructuring [Line Items]
Paycheck protection program	$ 208,900,000								$ 208,900,000
Deferred loan costs	1,700,000								$ 1,700,000
Period of loan sold									30 days
Minimum period seldom held									90 days
Mortgage warehousing maximum pay off period									30 days
Nonaccrual interest income									$ 0	$ 0
Non-accrual loans	22,142,000				$ 15,679,000				22,142,000	15,679,000
Non-performing TDRs	2,600,000								2,600,000
TDR loans	$ 2,610,000				2,006,000				$ 2,610,000	2,006,000
Restructured loan returned to accruing status number of Consecutive Payments of loan | payment	6								6
Restructured loan reported in TDRs	$ 4,403,000				5,360,000				$ 4,403,000	5,360,000
Specific reserves allocated to troubled debt restructuring	0								0
Credit loss expense	3,042,000	$ 2,052,000	$ 7,057,000	$ 8,600,000	$ 340,000	$ 376,000	$ 896,000	$ 364,000	20,751,000	1,976,000	$ 2,906,000
Minimum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans with an aggregate credit exposure	1,000,000								$ 1,000,000
Loans classified as TDR after a period									90 days
Minimum | Good Pass
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of consecutive years of profit for Good Pass Rating									3 years
Number of consecutive years of profit Unaudited Financial Information for Good Pass Rating									5 years
Number of years of Satisfactory Relationship with bank for Good Pass Rating									5 years
Maximum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans with an aggregate credit exposure	3,500,000								$ 3,500,000
Loans classified as TDR after a period									120 days
Maximum | Satisfactory Pass
Financing Receivable, Troubled Debt Restructuring [Line Items]
Minimum number of years of Satisfactory Repayment required for Satisfactory Pass Rating									2 years
CARES Act
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loan reported in TDRs	126,700,000								$ 126,700,000
Performing
Financing Receivable, Troubled Debt Restructuring [Line Items]
Restructured loan reported in TDRs	1,800,000								$ 1,800,000
Number TDRs returned to accrual status | loan									1
Loans Purchased With Evidence of Credit Deterioration
Financing Receivable, Troubled Debt Restructuring [Line Items]
Non-accrual loans	2,600,000								$ 2,600,000
Non-performing TDRs	$ 991,000								$ 991,000
Credit loss expense										133,000
Allowances for loan losses										$ 0