Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2012
Site Contingency [Line Items]
Litigation Settlement, Amount		$ 110,000
Environmental Costs Recovered	$ 37,000
Huntsville Site [Member]
Site Contingency [Line Items]
Environmental Remediation Expense To Date	6,300
Additional Expected Project Expenditures Low Estimate	4,100
Additional Expected Project Expenditures High Estimate	10,000
Norco Site [Member] | Remediation, Project Management, Regulatory Oversight, and Investigative and Feasability Studies [Member]
Site Contingency [Line Items]
Environmental Remediation Expense To Date	71,100
Additional Expected Project Expenditures Low Estimate	10,800
Additional Expected Project Expenditures High Estimate	$ 21,500