Retirement Benefit Plans, Net Periodic Benefit Cost (Details) - USD ($)	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	$ 266,436	$ 263,852
Interest cost	714,143	879,080
Expected return on plan assets	(1,365,261)	(1,190,330)
Amortization of prior service cost	24,845	24,845
Amortization of the net loss	325,034	290,549
Net periodic benefit cost (benefit)	(34,803)	267,996
Additional information [Abstract]
Contributions expected to be made by Company in next fiscal year	2,690,000
Employer contributions	400,000
Postretirement Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	10,855	8,216
Interest cost	11,667	20,346
Expected return on plan assets	(5,589)	(14,481)
Amortization of prior service cost	(2,063)	(1,268)
Amortization of the net loss	(6,377)	(20,507)
Net periodic benefit cost (benefit)	8,493	$ (7,694)
Additional information [Abstract]
Contributions expected to be made by Company in next fiscal year	50,000
Employer contributions	$ 11,000