Properties (Detail of Net Properties) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 28, 2012		Dec. 30, 2011
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 35,279		$ 33,704
Accumulated Depreciation	(9,229)		(8,730)
Properties - Net (Note 6)	26,050		24,974
Percentage of assets depreciated under the group-life method	85.00%		85.00%
Road - Total [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	23,419		22,379
Accumulated Depreciation	(5,153)		(4,889)
Properties - Net (Note 6)	18,266		17,490
Road - Rail and Other Track Material [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	6,177		5,949
Accumulated Depreciation	(1,131)		(1,021)
Properties - Net (Note 6)	5,046		4,928
Annual Depreciation Rate	2.90%	[1]	2.70%	[1]
Depreciation Method	Group Life		Group Life
Road - Ties [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	4,287		4,126
Accumulated Depreciation	(861)		(868)
Properties - Net (Note 6)	3,426		3,258
Annual Depreciation Rate	4.00%	[1]	3.70%	[1]
Depreciation Method	Group Life		Group Life
Road - Grading [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	2,407		2,379
Accumulated Depreciation	(414)		(382)
Properties - Net (Note 6)	1,993		1,997
Annual Depreciation Rate	1.50%	[1]	1.30%	[1]
Depreciation Method	Group Life		Group Life
Road - Ballast [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	2,528		2,446
Accumulated Depreciation	(624)		(610)
Properties - Net (Note 6)	1,904		1,836
Annual Depreciation Rate	2.80%	[1]	2.50%	[1]
Depreciation Method	Group Life		Group Life
Road - Bridges, Trestles, and Culverts [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	1,962		1,887
Accumulated Depreciation	(224)		(195)
Properties - Net (Note 6)	1,738		1,692
Annual Depreciation Rate	1.60%	[1]	1.40%	[1]
Depreciation Method	Group Life		Group Life
Road - Signals and Interlockers [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	1,787		1,680
Accumulated Depreciation	(302)		(198)
Properties - Net (Note 6)	1,485		1,482
Annual Depreciation Rate	3.40%	[1]	3.30%	[1]
Depreciation Method	Group Life		Group Life
Road - Buildings [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	926		874
Accumulated Depreciation	(316)		(342)
Properties - Net (Note 6)	610		532
Annual Depreciation Rate	2.50%	[1]	2.50%	[1]
Depreciation Method	Group Life		Group Life
Road - Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	3,345		3,038
Accumulated Depreciation	(1,281)		(1,273)
Properties - Net (Note 6)	2,064		1,765
Annual Depreciation Rate	4.70%	[1]	3.00%	[1]
Depreciation Method	Group Life		Group Life
Total Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	9,301		8,621
Accumulated Depreciation	(4,008)		(3,801)
Properties - Net (Note 6)	5,293		4,820
Equipment - Locomotive [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	4,747		4,455
Accumulated Depreciation	(2,079)		(1,960)
Properties - Net (Note 6)	2,668		2,495
Annual Depreciation Rate	3.60%	[1]	3.50%	[1]
Depreciation Method	Group Life		Group Life
Equipment - Freight Cars [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	3,088		2,821
Accumulated Depreciation	(1,119)		(1,095)
Properties - Net (Note 6)	1,969		1,726
Annual Depreciation Rate	3.10%	[1]	3.50%	[1]
Depreciation Method	Group Life		Group Life
Equipment - Work Equipment and Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	1,466		1,345
Accumulated Depreciation	(810)		(746)
Properties - Net (Note 6)	656		599
Annual Depreciation Rate	7.10%	[1]	7.30%	[1]
Depreciation Method	Group Life		Group Life
Land [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	1,745		1,832
Properties - Net (Note 6)	1,745		1,832
Construction in Progress [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	602		728
Properties - Net (Note 6)	602		728
Other properties [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	212		144
Accumulated Depreciation	(68)		(40)
Properties - Net (Note 6)	$ 144		$ 104
Depreciation Method	Straight Line		Straight Line
Minimum [Member] | Road - Total [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	6 years		6 years
Minimum [Member] | Road - Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	6 years
Minimum [Member] | Total Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	5 years		5 years
Minimum [Member] | Other properties [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	4 years		4 years
Maximum [Member] | Road - Total [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	80 years		80 years
Maximum [Member] | Road - Grading [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	80 years
Maximum [Member] | Total Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	38 years		35 years
Maximum [Member] | Equipment - Work Equipment and Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	38 years
Maximum [Member] | Other properties [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	30 years		30 years

[1] Composite depreciation rates, which are used in group-life depreciation, apply to railroad assets which account for more than 85% of total properties. All other property is depreciated on a straight-line basis over the asset’s useful life.