Retirement Benefit Plans, Defined Contribution Plan (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Defined Contribution Plan Disclosure [Line Items]
Total contributions made for the period	$ 814,496	$ 559,413
Regular Matching Contribution [Member]
Defined Contribution Plan Disclosure [Line Items]
Total contributions made for the period	166,015	116,475
Transitional Credit Contribution [Member]
Defined Contribution Plan Disclosure [Line Items]
Total contributions made for the period	124,108	135,370
Non-discretionary Contribution [Member]
Defined Contribution Plan Disclosure [Line Items]
Total contributions made for the period	524,373	$ 307,568
Non-Union U.S. Employees [Member]
Defined Contribution Plan Disclosure [Line Items]
Total contributions made for the period	$ 502,617