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Weighted Average Assumptions Used for Pension Plans (Detail)
12 Months Ended
Dec. 30, 2017
Dec. 31, 2016
Jan. 02, 2016
Defined Benefit Plan Disclosure [Line Items]      
Weighted average assumptions used to determine net periodic cost, Expected return on plan assets 8.00%    
Pension plans      
Defined Benefit Plan Disclosure [Line Items]      
Weighted average assumptions used to determine benefit obligations, Discount rate 3.58% 4.00% 4.25%
Weighted average assumptions used to determine benefit obligations, Rate of compensation increase 3.00% 3.00% 3.00%
Weighted average assumptions used to determine net periodic cost, Discount rate 4.00% 4.25% 4.00%
Weighted average assumptions used to determine net periodic cost, Expected return on plan assets 8.00% 8.00% 8.00%
Weighted average assumptions used to determine net periodic cost, Rate of compensation increase 3.00% 3.00% 4.00%
Pension plans | Benefit Obligations      
Defined Benefit Plan Disclosure [Line Items]      
Weighted average assumptions used to determine Measurement date Dec. 31, 2017 Dec. 31, 2016 Dec. 31, 2015
Pension plans | Net (Income) Cost      
Defined Benefit Plan Disclosure [Line Items]      
Weighted average assumptions used to determine Measurement date Jan. 01, 2017 Jan. 01, 2016 Jan. 01, 2015
Postretirement Benefit Plans | Benefit Obligations      
Defined Benefit Plan Disclosure [Line Items]      
Weighted average assumptions used to determine benefit obligations, Discount rate 3.36% 3.66% 3.83%
Weighted average assumptions used to determine benefit obligations, Measurement date Dec. 31, 2017 Dec. 31, 2016 Dec. 31, 2015
Health care cost trend rate, Initial rate 6.00% 6.50% 8.00%
Health care cost trend rate, Ultimate rate 5.00% 5.00% 5.00%
Health care cost trend rate, Year trend reaches the ultimate rate 2022 2023 2022
Postretirement Benefit Plans | Net Periodic Benefit Cost      
Defined Benefit Plan Disclosure [Line Items]      
Weighted average assumptions used to determine net periodic cost, Discount rate 3.66% 3.83% 3.50%
Health care cost trend rate, Initial rate 6.50% 8.00% 8.00%
Health care cost trend rate, Ultimate rate 5.00% 5.00% 5.00%
Health care cost trend rate, Year trend reaches the ultimate rate 2023 2022 2021
Weighted average assumptions used to determine net periodic cost, Measurement date Jan. 01, 2017 Jan. 01, 2016 Jan. 01, 2015