Retirement Benefit Plans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Pension Benefits [Member]
Service cost	$ 266,435	$ 263,852	$ 799,305	$ 791,558
Interest cost	714,143	879,080	2,142,428	2,637,240
Expected return on plan assets	1,365,261	1,190,329	4,095,784	3,570,990
Amortization of prior service cost	24,845	24,845	74,535	74,535
Amortization of the net loss	(325,033)	(290,548)	(975,101)	(871,647)
Net periodic benefit cost (benefit)	(34,805)	267,996	(104,415)	803,990
Postretirement Benefits [Member]
Service cost	10,855	8,533	32,565	24,965
Interest cost	11,667	1,874	35,001	42,566
Expected return on plan assets	5,589	(7,938)	16,767	21,025
Amortization of prior service cost	(2,063)	(1,268)	(6,189)	(3,804)
Amortization of the net loss	(6,377)	(5,560)	19,131	35,454
Net periodic benefit cost (benefit)	8,493	(204,434)	25,479	(219,823)
Gain on significant event	$ 0	$ (227,071)	$ 0	$ (227,071)