Properties (Detail of Net Properties) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 26, 2014	Dec. 27, 2013
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	$ 39,343	$ 37,184
Accumulated Depreciation	(10,759)	(9,893)
Properties - Net	28,584	27,291
Road - Total [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	26,125	24,618
Accumulated Depreciation	(6,148)	(5,592)
Properties - Net	19,977	19,026
Road - Rail and Other Track Material [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	6,771	6,452
Accumulated Depreciation	(1,400)	(1,270)
Properties - Net	5,371	5,182
Annual Depreciation Rate	2.50%	2.90%
Depreciation Method	Group Life	Group Life
Road - Ties [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	4,807	4,534
Accumulated Depreciation	(1,060)	(947)
Properties - Net	3,747	3,587
Annual Depreciation Rate	3.70%	4.00%
Depreciation Method	Group Life	Group Life
Road - Grading [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	2,460	2,425
Accumulated Depreciation	(481)	(448)
Properties - Net	1,979	1,977
Annual Depreciation Rate	1.40%	1.50%
Depreciation Method	Group Life	Group Life
Road - Ballast [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	2,693	2,612
Accumulated Depreciation	(679)	(645)
Properties - Net	2,014	1,967
Annual Depreciation Rate	2.70%	2.80%
Depreciation Method	Group Life	Group Life
Road - Bridges, Trestles, and Culverts [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	2,119	2,008
Accumulated Depreciation	(278)	(250)
Properties - Net	1,841	1,758
Annual Depreciation Rate	1.60%	1.60%
Depreciation Method	Group Life	Group Life
Road - Signals and Interlockers [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	2,103	1,922
Accumulated Depreciation	(356)	(291)
Properties - Net	1,747	1,631
Annual Depreciation Rate	4.00%	3.40%
Depreciation Method	Group Life	Group Life
Road - Buildings [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	1,102	1,011
Accumulated Depreciation	(377)	(355)
Properties - Net	725	656
Annual Depreciation Rate	2.50%	2.50%
Depreciation Method	Group Life	Group Life
Road - Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	4,070	3,654
Accumulated Depreciation	(1,517)	(1,386)
Properties - Net	2,553	2,268
Annual Depreciation Rate	4.20%	4.70%
Depreciation Method	Group Life	Group Life
Total Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	10,108	9,764
Accumulated Depreciation	(4,526)	(4,225)
Properties - Net	5,582	5,539
Equipment - Locomotive [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	5,036	4,987
Accumulated Depreciation	(2,325)	(2,176)
Properties - Net	2,711	2,811
Annual Depreciation Rate	3.60%	3.60%
Depreciation Method	Group Life	Group Life
Equipment - Freight Cars [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	3,244	3,111
Accumulated Depreciation	(1,169)	(1,135)
Properties - Net	2,075	1,976
Annual Depreciation Rate	3.20%	3.10%
Depreciation Method	Group Life	Group Life
Equipment - Work Equipment and Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	1,828	1,666
Accumulated Depreciation	(1,032)	(914)
Properties - Net	796	752
Annual Depreciation Rate	7.10%	7.10%
Depreciation Method	Group Life	Group Life
Land [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	1,875	1,842
Properties - Net	1,875	1,842
Construction in Progress [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	1,196	854
Properties - Net	1,196	854
Other properties [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Cost	39	106
Accumulated Depreciation	(85)	(76)
Properties - Net	$ (46)	$ 30
Depreciation Method	Straight Line	Straight Line
Minimum [Member] | Road - Total [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	8 years	6 years
Minimum [Member] | Road - Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	8 years
Minimum [Member] | Total Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	3 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	90 years	80 years
Maximum [Member] | Road - Grading [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	90 years
Maximum [Member] | Total Equipment [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Estimated useful life	38 years	38 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