Casualty, Environmental and Other Reserves (Loss Contingencies Accrual) (Details) (USD $) In Millions, unless otherwise specified	Dec. 28, 2012		Dec. 30, 2011		Dec. 31, 2010		Dec. 25, 2009
Contingencies [Line Items]
Casualty, environmental and other reserves, current	$ 140		$ 167
Casualty, environmental and other reserves, long-term	337		352
Casualty, environmental and other reserves, total	477		519		541		621
Casualty [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	88		110
Casualty, environmental and other reserves, long-term	237		262
Casualty, environmental and other reserves, total	325		372		375		459
Personal Injury [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	75		93
Casualty, environmental and other reserves, long-term	158		168
Casualty, environmental and other reserves, total	233		261
Occupational [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	5		6
Casualty, environmental and other reserves, long-term	31		37
Casualty, environmental and other reserves, total	36		43
Asbestos [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	8		11
Casualty, environmental and other reserves, long-term	48		57
Casualty, environmental and other reserves, total	56		68
Environmental [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	33		31
Casualty, environmental and other reserves, long-term	55		52
Casualty, environmental and other reserves, total	88		83		107		97
Other [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	19		26
Casualty, environmental and other reserves, long-term	45		38
Casualty, environmental and other reserves, total	$ 64	[1]	$ 64	[1]	$ 59	[1]	$ 65	[1]

[1] Separation liabilities and freight rate dispute reserves have been reclassified to other current liabilities and other long-term liabilities.