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Employee Benefit Plans (Details)
 12 Months Ended
Dec. 31, 2020
USD ($)
employee
postretirementBenefitPlan
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Defined contribution plan [Abstract]      
Defined contribution plan service period (in months) 3 months    
Defined contribution plan employer maximum percentage match of annual salary based on employee contribution 3.00%    
Defined contribution plan employer maximum percentage of annual profit-sharing contribution to plan for benefit of employee (in hundredths) 3.00% 2.00% 2.00%
Expense related to 401(k) plan $ 981,000 $ 575,000 $ 578,000
Defined benefit plans, general information The Bank also provides unfunded supplemental retirement benefits for certain officers, payable in installments over 20 years commencing upon retirement or death. The agreements consist of individual contracts with differing characteristics that, when taken together, do not constitute a post-retirement plan.    
Unfunded, supplemental retirement benefits payable period 20 years    
Pension expense $ 450,000 165,000 $ 176,000
Accrued pension liability $ 2,991,000 $ 2,828,000  
Number of post-retirement benefit plans | postretirementBenefitPlan 2    
Number of active employees aged 50 and over | employee 6    
Employee benefit plan age (in years) 50 years    
Post-retirement benefit plan health insurance subsidy range minimum per month per person $ 40    
Post-retirement benefit plan health insurance subsidy range maximum per month per person 1,200    
Expected future benefit payments in 2021 97,000    
Expected future benefit payments in 2022 94,000    
Expected future benefit payments in 2023 90,000    
Expected future benefit payments in 2024 98,000    
Expected future benefit payments in 2025 95,000    
Expected future benefit payments in 2025 through 2028 351,000    
Estimated plan expense $ 29,000