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Postretirement Plans - Summary of Change in Fair Value of Plan Assets (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 30, 2017
Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year $ 1,110.8 $ 1,049.2
Actual return on plan assets 175.7 73.5
Employer contributions 69.6 68.7
Plan participant contributions 0.6 1.0
Benefits paid (66.6) (63.2)
Fair value of plan assets at end of year 1,305.0 1,110.8
Unfunded status at end of year (162.6) (250.6)
U.S. Postretirement Health Care Plans [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 13.2 13.7
Actual return on plan assets 1.3 0.5
Employer contributions 2.8 2.9
Plan participant contributions 0.4 0.5
Benefits paid (4.3) (4.4)
Fair value of plan assets at end of year 13.4 13.2
Unfunded status at end of year $ (39.1) $ (40.0)