Loans Receivable, Net - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($) loan	Sep. 30, 2020 loan	Sep. 30, 2021 USD ($) loan	Sep. 30, 2020 loan	Dec. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivables 90 days past due and still accruing					$ 0
Troubled debt restructured loans	$ 19,600,000		$ 19,600,000		17,500,000
Non-accrual loan total troubled debt restructurings			10,000,000		5,500,000
Specific reserves to loans accruing troubled debt restructurings	0		0		0
Troubled debt restructured loans with accrual interest	9,600,000		9,600,000		12,000,000
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in mortgage and consumer loans collateralized, foreclosure amount	416,000		416,000		1,900,000
Commercial real estate – owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in mortgage and consumer loans collateralized, foreclosure amount	$ 12,500,000		$ 12,500,000		13,800,000
Number of Loans | loan	1		1	1
Commercial Real Estate – Investor
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in mortgage and consumer loans collateralized, foreclosure amount	$ 8,500,000		$ 8,500,000		18,300,000
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Recorded investment in mortgage and consumer loans collateralized, foreclosure amount	669,000		669,000		1,400,000
Foreclosed property held	$ 106,000		$ 106,000		$ 106,000
Number of Loans | loan		1	3	5
Commercial real estate – investor
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan		1	1	1
Investor loan			$ 923,000