Properties (Significant Property Disposition) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended							0 Months Ended	12 Months Ended		0 Months Ended			1 Months Ended
	Dec. 28, 2012 mi	Dec. 30, 2011	Dec. 31, 2010	Dec. 28, 2012 Other Current Liabilities [Member]	Dec. 30, 2011 Other Current Liabilities [Member]	Dec. 28, 2012 Other Long-term Liabilities [Member]	Dec. 30, 2011 Other Long-term Liabilities [Member]	Nov. 30, 2011 SunRail Transaction - Sale of Corridor [Member] mi	Dec. 28, 2012 SunRail Transaction - Sale of Corridor [Member]	Dec. 30, 2011 SunRail Transaction - Sale of Corridor [Member]	Nov. 30, 2011 SunRail Transaction - Sale of Corridor [Member] Maximum [Member]	Nov. 30, 2011 SunRail Transaction - Sale of Corridor [Member] Cash [Member]	Nov. 30, 2011 SunRail Transaction - Sale of Corridor [Member] Accounts Receivable [Member]	Nov. 30, 2011 Capital Addition Purchase Commitments [Member] SunRail Transaction - Sale of Corridor [Member]
Significant Acquisitions and Disposals [Line Items]
Total number of rail route miles	21,000							61
Proceeds from disposal of property, total								$ 173
Proceeds from property dispositions	186	240	108									148
Proceeds from property dispositions in form of receivables held in escrow													25
Proceeds from property dispositions in form of government grants											259
Long-term purchase commitment														500
Long-term purchase commitment, period														8 years
Abnormal gains	104	14	(30)						94	14
Deferred gain on sale of real estate				$ 43	$ 95	$ 9	$ 37	$ 160	$ 52	$ 132