Debt and Credit Agreements (Long-term Debt Instruments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 28, 2012		Dec. 30, 2011
Debt Instrument [Line Items]
Total Long-term Debt Maturities (including current portion)	$ 9,832		$ 9,241
Less Debt Due within One Year	(780)		(507)
Long-term Debt (excluding current portion)	9,052		8,734
Notes Payable [Member]
Debt Instrument [Line Items]
Total Long-term Debt Maturities (including current portion)	9,151		8,486
Average Interest Rates (in hundredths)	5.80%
Equipment Obligations [Member]
Debt Instrument [Line Items]
Total Long-term Debt Maturities (including current portion)	667	[1]	741	[1]
Average Interest Rates (in hundredths)	7.20%	[1]
Capital Leases [Member]
Debt Instrument [Line Items]
Total Long-term Debt Maturities (including current portion)	12		10
Average Interest Rates (in hundredths)	11.10%
Convertible Debt [Member]
Debt Instrument [Line Items]
Total Long-term Debt Maturities (including current portion)	$ 2		$ 4
Average Interest Rates (in hundredths)	1.00%

[1] These obligations are secured by an interest in certain railroad equipment.