Postretirement Benefits - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020 USD ($)
Compensation And Retirement Disclosure [Abstract]
Postretirement Benefits Description Of Medical Coverage	The Bank employees who retired prior to April 1, 1997, and who completed 20 years of service after age 40 receive full medical coverage at no cost.
Maximum Reimburse Medical Expenses	$ 10,000
Postretirement Benefits Description Of Medical Coverage One	The Bank employees who were born after December 31, 1950, are not eligible for the medical coverage described above at retirement.
Other Comprehensive Income Loss Defined Benefit Plan Expected To Be Recognized In Net Postretirement Benefit Cost Before Tax	$ 0
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Reclassification Adjustment, before Tax	13,000
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Tax	10,000
Defined Benefits Plan, Expected Contribution, Before Reflecting Subsidy Payments	$ 174,000