Retirement Benefit Plans, Net Periodic Benefit Cost (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	$ 263,852	$ 329,959	$ 791,558	$ 989,881
Interest cost	879,080	776,790	2,637,240	2,330,373
Expected return on plan assets	(1,190,329)	(1,304,879)	(3,570,990)	(3,914,637)
Amortization of prior service cost	24,845	32,691	74,535	98,072
Amortization of the net loss	290,548	277,528	871,647	832,584
Net periodic benefit cost	267,996	112,089	803,990	336,273
Additional information [Abstract]
Contributions expected to be made by Company in next fiscal year	600,000		600,000
Employer contributions			286,000
Postretirement Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	8,533	9,256	24,965	27,768
Interest cost	1,874	19,290	42,566	57,871
Expected return on plan assets	7,938	(13,913)	(21,025)	(41,738)
Gain on Significant Event	(227,071)	0	(227,071)	0
Amortization of prior service cost	(1,268)	(1,268)	(3,804)	(3,804)
Amortization of the net loss	5,560	(16,397)	(35,454)	(49,193)
Net periodic benefit cost	(204,434)	$ (3,032)	(219,823)	$ (9,096)
Additional information [Abstract]
Contributions expected to be made by Company in next fiscal year	$ 105,000		105,000
Employer contributions			$ 45,000