Nature of Operations and Significant Accounting Policies (Amortization of Gain from Property Disposition) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended
	Nov. 30, 2011	Jun. 28, 2013	Jun. 29, 2012	Jun. 28, 2013	Jun. 29, 2012
Significant Acquisitions and Disposals [Line Items]
Total number of rail route miles		21,000		21,000
Investment obligation made during the period				$ 1,085	$ 1,223
SunRail Transaction - Sale of Corridor [Member]
Significant Acquisitions and Disposals [Line Items]
Gain on sale of real estate		14	20	43	39
Deferred gain on sale of real estate	160
Capital Additions [Member] | SunRail Transaction - Sale of Corridor [Member]
Significant Acquisitions and Disposals [Line Items]
Obligation to invest in routine captial expenditures and maintenance	500
Obligation to invest in routine captial expenditures and maintenance, term (in years)	8 years
Investment obligation made during the period		$ 46	$ 72	$ 142	$ 146