Summary of Effect of One Percent Point Change in Assumed Health Care Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Compensation And Retirement Disclosure [Abstract]
One-Percentage Point Decrease, Effect on total of service and interest cost	$ (52)	$ (47)	$ (58)
One-Percentage Point Decrease, Effect on postretirement benefit obligation	(467)	(473)	(427)
One-Percentage Point Increase, Effect on total of service and interest cost	61	55	67
One-Percentage Point Increase, Effect on postretirement benefit obligation	$ 524	$ 533	$ 480

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- Definition

Amount of decrease in accumulated postretirement benefit obligation from one-percentage-point decrease in assumed health care cost trend rate.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (m)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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- Definition

Amount of decrease in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point decrease in assumed health care cost trend rate.

+ References

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- Definition

Amount of increase in accumulated postretirement benefit obligation from one-percentage-point increase in assumed health care cost trend rate.

+ References

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- Definition

Amount of increase in service and interest cost components of net periodic postretirement benefit cost from one-percentage-point increase in assumed health care cost trend rate.

+ References

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