ACCUMULATED OTHER COMPREHENSIVE LOSS - Summary of accumulated other comprehensive income (loss) (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 144,622,102	$ 126,331,951	$ 128,468,076	$ 74,977,847
Comprehensive (loss) income	1,061,869	1,016,855	5,590,425	1,096,598
Ending balance	145,615,116	127,399,899	145,615,116	127,399,899
Unrealized gain and losses on available for sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	121,332	70,352	100,569	111,892
Other comprehensive gain (loss)	(11,689)		9,074	(8,996)
Other comprehensive gain before reclassification		32,543
Comprehensive (loss) income	(11,689)	32,543	9,074	(8,996)
Ending balance	109,643	102,895	109,643	102,895
Benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(310,820)	(369,764)	(373,582)	(425,557)
Amounts reclassified	31,383	27,896	94,145	83,689
Comprehensive (loss) income	31,383	27,896	94,145	83,689
Ending balance	(279,437)	(341,868)	(279,437)	(341,868)
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(189,488)	(299,412)	(273,013)	(313,665)
Other comprehensive gain (loss)	(11,689)		9,074	(8,996)
Other comprehensive gain before reclassification		32,543
Amounts reclassified	31,383	27,896	94,145	83,689
Comprehensive (loss) income	19,694	60,439	103,219	74,693
Ending balance	$ (169,794)	$ (238,973)	$ (169,794)	$ (238,973)