Casualty, Environmental and Other Reserves (Loss Contingencies Accrual) (Details) (USD $) In Millions, unless otherwise specified	Dec. 30, 2011		Dec. 31, 2010		Dec. 25, 2009		Dec. 26, 2008
Contingencies [Line Items]
Casualty, environmental and other reserves, current	$ 183		$ 176
Casualty, environmental and other reserves, long-term	458		502
Casualty, environmental and other reserves, total	641		678		737		879
Casualty [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	110		97
Casualty, environmental and other reserves, long-term	262		278
Casualty, environmental and other reserves, total	372		375		459		566
Personal Injury [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	93		78
Casualty, environmental and other reserves, long-term	168		176
Casualty, environmental and other reserves, total	261		254
Occupational [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	6		10
Casualty, environmental and other reserves, long-term	37		30
Casualty, environmental and other reserves, total	43		40
Asbestos [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	11		9
Casualty, environmental and other reserves, long-term	57		72
Casualty, environmental and other reserves, total	68		81
Separation [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	10		16
Casualty, environmental and other reserves, long-term	38		44
Casualty, environmental and other reserves, total	48		60		73		87
Environmental [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	31		37
Casualty, environmental and other reserves, long-term	52		70
Casualty, environmental and other reserves, total	83		107		97		100
Other [Member]
Contingencies [Line Items]
Casualty, environmental and other reserves, current	32		26
Casualty, environmental and other reserves, long-term	106		110
Casualty, environmental and other reserves, total	$ 138	[1]	$ 136	[1]	$ 108	[1]	$ 126	[1]

[1] Other reserve accruals were higher in 2010 due to an increase in freight rate reserves related to various rate disputes. These accruals were lower in 2009 primarily due to a reduction in freight loss and damage claims as a result of volume declines. These amounts are recorded as a reduction in revenue rather than expense because they represent liabilities for customer claims regarding the rates charged by the Company for its transportation services.