Postretirement Plans - Summary of Change in Fair Value of Plan Assets (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Jan. 03, 2015	Dec. 28, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 1,015.4	$ 964.0
Plan participants' contributions	1.2	1.2
Employer contributions	44.8	35.3
Actual return on VEBA plan assets	112.9	75.1
Benefits paid	(59.2)us-gaap_DefinedBenefitPlanBenefitsPaid	(59.5)us-gaap_DefinedBenefitPlanBenefitsPaid
Fair value of plan assets at end of year	1,103.4	1,015.4
Unfunded status at end of year	(222.5)	(136.9)
U.S. Postretirement Health Care Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	15.0	15.1
Plan participants' contributions	1.2	1.2
Employer contributions	3.6	3.0
Actual return on VEBA plan assets	0.9	2.5
Benefits paid	(6.0)	(6.8)
Fair value of plan assets at end of year	14.7	15.0
Unfunded status at end of year	$ (47.3)	$ (46.5)

Defined benefit plan, unfunded status of plan

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- Definition

The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Actual Return on Plan Assets (Component of Net Periodic Postretirement Benefit Cost)

-URI http://asc.fasb.org/extlink&oid=6504192

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Actual Return on Plan Assets (Component of Net Periodic Pension Cost)

-URI http://asc.fasb.org/extlink&oid=6504226

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- Definition

The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Postretirement Benefits

-URI http://asc.fasb.org/extlink&oid=6521376

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Benefits

-URI http://asc.fasb.org/extlink&oid=6506267

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

+ References

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- Definition

The amount of contributions made by plan participants. This item represents a periodic increase to the plan obligation and an increase to plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ 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 (b)

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-Topic 715

-SubTopic 30

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