Casualty, Environmental and Other Reserves (Casualty) (Details) - Casualty [Member]	12 Months Ended
	Dec. 25, 2015 USD ($) claim	Dec. 26, 2014 USD ($)	Dec. 27, 2013 USD ($)	Dec. 28, 2012 USD ($)
Loss Contingencies [Line Items]
Reserves	$ 269,000,000	$ 265,000,000	$ 280,000,000	$ 325,000,000
Self-insured retention amount per injury	$ 50,000,000
Individual claims expected to exceed self-insured retention amount | claim	0
Change in estimate recorded to adjust reserves	$ 0	$ 0	$ 0