Postretirement Health Care Plans - Net Periodic Postretirement Health Care Cost (Detail) - Other Postretirement Benefit Plans, Defined Benefit [Member] - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Postretirement Health Care Plans [Line Items]
Interest cost	$ 0.5	$ 0.5	$ 1.0	$ 1.1
Expected return on plan assets	(0.2)	(0.2)	(0.4)	(0.4)
Amortization of unrecognized loss (gain)		0.1	(0.1)
Net periodic pension cost	$ 0.3	$ 0.4	$ 0.5	$ 0.7

Defined benefit plan, amortization of unrecognized gains (losses)

No definition available.

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Period Type:	duration

- Definition

Postretirement Health Care Plans [Line Items]

+ References

No definition available.

+ Details

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- Definition

Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan.

+ References

+ Details

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

- Definition

Amount of cost recognized for passage of time related to defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of net periodic benefit cost (credit) for defined benefit plan.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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