Retirement Benefit Plans (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Additional information [Abstract]
Reduction in pension expense			$ 270,000
Pension Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	$ 317,358	$ 528,552	634,718	$ 1,341,557
Interest cost	791,055	1,007,763	1,582,112	1,774,343
Expected return on plan assets	(1,195,892)	(1,238,231)	(2,391,787)	(2,482,172)
Amortization of prior service cost	36,436	50,141	72,874	100,284
Amortization of the net loss	307,873	415,093	615,743	1,042,148
Net periodic benefit cost	256,830	763,318	513,660	1,776,160
Additional information [Abstract]
Contributions required by the Company in defined benefit plan			700,000
Employer contributions made			161,000
Postretirement Benefits [Member]
Components of the net periodic benefit cost [Abstract]
Service cost	6,848	3,900	13,695	14,650
Interest cost	20,207	26,936	40,414	47,436
Expected return on plan assets	(12,873)	(12,016)	(25,747)	(23,766)
Amortization of prior service cost	(5,361)	(5,945)	(10,722)	(11,945)
Amortization of the net loss	(19,401)	(33,461)	(38,801)	(46,961)
Net periodic benefit cost	$ (10,580)	$ (20,586)	(21,161)	$ (20,586)
Additional information [Abstract]
Contributions required by the Company in defined benefit plan			103,000
Employer contributions made			$ 72,000