Contingencies (Detail) - USD ($) $ in Millions	6 Months Ended
Jun. 29, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies, Significant Assumptions	The reserves are established based upon analyses conducted by the Company’s engineers and outside consultants and are adjusted from time to time based upon ongoing studies, the difference between actual and estimated costs, and other factors. The reserves may also be affected by rulings and negotiations with regulatory agencies.
Undiscounted reserve balance	$ 6.4	$ 6.5

Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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