Nature of Operations and Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2011 weeks	Dec. 31, 2010 weeks	Sep. 24, 2010 weeks	Sep. 30, 2011 weeks	Sep. 24, 2010 weeks	Dec. 31, 2011 weeks	Dec. 31, 2010 weeks
Background
Total number of rail route miles	21,000			21,000
Rail network states number	23			23
Fiscal Year
Number Weeks Fiscal Quarter	13	14	13
Number Weeks Year To Date				39	39
Number Weeks Fiscal Year Reporting Calendar						52	53
Comprehensive Earnings
Total comprehensive earnings, net of tax	$ 473		$ 431	$ 1,400	$ 1,200
Accumulated other comprehensive loss	(738)	(771)		(738)			(771)
Allowance for Doubtful Accounts
Current portion of allowance for doubtful accounts receivable	40	38		40			38
Retained Earnings
Reclassification between retained earnings and other capital as result of share repurchases	978
Other Additional Capital	$ 0			$ 0