Employee Benefit Plans (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended
Apr. 01, 2018	Mar. 26, 2017
Pension and postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Other comprehensive income (loss) before reclassifications	$ 96,374	$ 0

Amount before tax and reclassification adjustments of other comprehensive income (loss) attributable to parent.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669686-108580

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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