Retirement Benefit Plans, Defined Contribution Plan (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Defined Contribution Plan [Abstract]
Total contributions for the period	$ 215,811	$ 203,804	$ 1,268,377	$ 993,530
Regular Matching Contribution [Member]
Defined Contribution Plan [Abstract]
Total contributions for the period	129,968	111,291	436,088	346,713
Transitional Credit Contribution [Member]
Defined Contribution Plan [Abstract]
Total contributions for the period	68,128	76,526	273,742	307,597
Non-discretionary Contribution [Member]
Defined Contribution Plan [Abstract]
Total contributions for the period	$ 17,715	$ 15,987	558,547	$ 339,220
Non-Union U.S. Employees [Member]
Defined Contribution Plan [Abstract]
Total contributions for the period			$ 502,617