Summary of Recognized Settlement Charges by Quarter (Detail) - USD ($) $ in Thousands	3 Months Ended	4 Months Ended	12 Months Ended
Dec. 29, 2018	Oct. 06, 2018	Jul. 14, 2018	Dec. 30, 2017	Oct. 07, 2017	Dec. 31, 2016	Oct. 08, 2016	Jul. 16, 2016	Apr. 21, 2018	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Pension And Other Postretirement Benefit Expense [Abstract]
Settlement loss	$ 1,148	$ 930	$ 1,035	$ 1,619	$ 3,030	$ 173	$ 1,832	$ 4,641	$ 4,668	$ 7,781	$ 4,649	$ 6,646

Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(7)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)(7)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e2709-114920

Name:	us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration