Property and Equipment (including Concession Assets) Schedule of Property and Equipment (including Concession Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Cost	$ 9,035.0		$ 8,073.7
Accumulated Depreciation	(1,880.3)		(1,717.4)
Net Book Value	7,154.7		6,356.3
Land [Member]
Property, Plant and Equipment [Line Items]
Cost	216.8		216.4
Accumulated Depreciation	0		0
Net Book Value	216.8		216.4
Concession land rights [Member]
Property, Plant and Equipment [Line Items]
Cost	141.2		141.2
Accumulated Depreciation	(22.3)		(20.9)
Net Book Value	118.9		120.3
Depreciation Rates	1.00%		1.00%
Road property [Member]
Property, Plant and Equipment [Line Items]
Cost	6,294.7		5,955.7
Accumulated Depreciation	(1,381.0)		(1,299.0)
Net Book Value	4,913.7		4,656.7
Depreciation Rates	2.80%		2.70%
Rail and other track material [Member]
Property, Plant and Equipment [Line Items]
Cost	1,707.6		1,617.8
Accumulated Depreciation	(361.1)		(341.1)
Net Book Value	1,346.5		1,276.7
Rail and other track material [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Depreciation Rates	1.90%		1.80%
Rail and other track material [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Depreciation Rates	3.20%		3.10%
Ties [Member]
Property, Plant and Equipment [Line Items]
Cost	1,484.7		1,425.1
Accumulated Depreciation	(312.6)		(303.7)
Net Book Value	1,172.1		1,121.4
Ties [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Depreciation Rates	2.00%		2.00%
Ties [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Depreciation Rates	4.20%		4.30%
Grading [Member]
Property, Plant and Equipment [Line Items]
Cost	839.6		829.6
Accumulated Depreciation	(137.9)		(129.7)
Net Book Value	701.7		699.9
Depreciation Rates	1.00%		1.10%
Bridges and tunnels [Member]
Property, Plant and Equipment [Line Items]
Cost	669.5		606.4
Accumulated Depreciation	(123.8)		(116.5)
Net Book Value	545.7		489.9
Depreciation Rates	1.20%		1.20%
Ballast [Member]
Property, Plant and Equipment [Line Items]
Cost	649.8		602.7
Accumulated Depreciation	(170.0)		(155.2)
Net Book Value	479.8		447.5
Ballast [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Depreciation Rates	2.70%		2.60%
Ballast [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Depreciation Rates	4.80%		4.80%
Other road property [Member]
Property, Plant and Equipment [Line Items]
Cost	943.5	[1]	874.1	[1]
Accumulated Depreciation	(275.6)	[1]	(252.8)	[1]
Net Book Value	667.9	[1]	621.3	[1]
Depreciation Rates	3.10%	[1]	2.90%	[1]
Equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	1,979.9		1,436.2
Accumulated Depreciation	(355.1)		(286.2)
Net Book Value	1,624.8		1,150.0
Depreciation Rates	5.00%		4.80%
Locomotives [Member]
Property, Plant and Equipment [Line Items]
Cost	1,310.3		1,017.4
Accumulated Depreciation	(238.3)		(193.2)
Net Book Value	1,072.0		824.2
Depreciation Rates	4.70%		5.00%
Freight cars [Member]
Property, Plant and Equipment [Line Items]
Cost	610.6		362.2
Accumulated Depreciation	(98.3)		(78.9)
Net Book Value	512.3		283.3
Depreciation Rates	5.30%		3.90%
Other equipment [Member]
Property, Plant and Equipment [Line Items]
Cost	59.0		56.6
Accumulated Depreciation	(18.5)		(14.1)
Net Book Value	40.5		42.5
Depreciation Rates	8.20%		7.40%
Technology and other [Member]
Property, Plant and Equipment [Line Items]
Cost	160.9		152.8
Accumulated Depreciation	(121.9)		(111.3)
Net Book Value	39.0		41.5
Depreciation Rates	13.20%		11.60%
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Cost	241.5		171.4
Accumulated Depreciation	0		0
Net Book Value	$ 241.5		$ 171.4

[1] Other includes signals, buildings and other road assets.