Accumulated Other Comprehensive Loss- Summary of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net of tax amount	$ 74,977,847	$ 72,477,768	$ 68,308,489
Net Unrealized Gain of Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before tax	155,644	110,196
Tax effect	(43,752)	(59,635)
Net of tax amount	111,892	50,561
Benefit Plans Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before tax	(591,960)	(666,987)
Tax effect	166,403	299,307
Net of tax amount	(425,557)	(367,680)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net of tax amount	$ (313,665)	$ (317,119)	$ (349,721)