Casualty, Environmental and Other Reserves - Narrative (Details)	6 Months Ended
	Jun. 24, 2016 USD ($) claim site	Dec. 25, 2015 USD ($)
All Contingencies Reserves [Line Items]
Total reserves	$ 379,000,000	$ 400,000,000
Casualty
All Contingencies Reserves [Line Items]
Total reserves	246,000,000	269,000,000
Self-insured retention amount, per occurrence	$ 50,000,000
Number of individual claims expected to exceed self insured retention amount | claim	0
Environmental
All Contingencies Reserves [Line Items]
Total reserves	$ 84,000,000	82,000,000
Environmental impaired sites | site	232
Other
All Contingencies Reserves [Line Items]
Total reserves	$ 49,000,000	$ 49,000,000