Retirement Benefit Plans (Details) - USD ($)	3 Months Ended
	Apr. 03, 2021	Mar. 28, 2020
Pension Benefit [Member]
Service cost	$ 271,833	$ 266,436
Interest cost	504,255	714,143
Expected return on plan assets	(1,448,674)	(1,365,261)
Amortization of prior service cost	24,845	24,845
Amortization of the net loss	432,539	325,034
Net periodic benefit cost	(215,202)	(34,803)
Other Postretirement Benefit [Member]
Service cost	13,626	10,855
Interest cost	9,842	11,667
Expected return on plan assets	(6,420)	(5,589)
Amortization of prior service cost	0	(2,063)
Amortization of the net loss	(3,094)	(6,377)
Net periodic benefit cost	(13,954)	(8,493)
Gain on significant event	$ 0	$ 0