Property and Equipment and Leases Property and Equipment (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 4,462,019,000us-gaap_PropertyPlantAndEquipmentGross	$ 3,993,393,000us-gaap_PropertyPlantAndEquipmentGross
Accumulated depreciation	(673,537,000)	(552,649,000)
Property and equipment, net	3,788,482,000us-gaap_PropertyPlantAndEquipmentNet	3,440,744,000us-gaap_PropertyPlantAndEquipmentNet
Depreciation expense	135,000,000us-gaap_Depreciation	119,200,000us-gaap_Depreciation	66,600,000us-gaap_Depreciation
Land and land improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	582,383,000	547,163,000
Accumulated depreciation	0	0
Property and equipment, net	582,383,000	547,163,000
Buildings and leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	126,860,000	123,295,000
Accumulated depreciation	(22,719,000)	(19,834,000)
Property and equipment, net	104,141,000	103,461,000
Bridges/tunnels/culverts
Property, Plant and Equipment [Line Items]
Total property and equipment	636,605,000	556,108,000
Accumulated depreciation	(60,771,000)	(46,162,000)
Property and equipment, net	575,834,000	509,946,000
Track property
Property, Plant and Equipment [Line Items]
Total property and equipment	2,350,647,000	2,078,084,000
Accumulated depreciation	(357,969,000)	(297,207,000)
Property and equipment, net	1,992,678,000	1,780,877,000
Total property
Property, Plant and Equipment [Line Items]
Total property and equipment	3,696,495,000	3,304,650,000
Accumulated depreciation	(441,459,000)	(363,203,000)
Property and equipment, net	3,255,036,000	2,941,447,000
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	13,997,000	11,307,000
Accumulated depreciation	(8,352,000)	(5,967,000)
Property and equipment, net	5,645,000	5,340,000
Locomotives and railcars
Property, Plant and Equipment [Line Items]
Total property and equipment	531,948,000	493,977,000
Accumulated depreciation	(145,073,000)	(118,544,000)
Property and equipment, net	386,875,000	375,433,000
Vehicles and mobile equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	54,419,000	42,127,000
Accumulated depreciation	(31,209,000)	(27,112,000)
Property and equipment, net	23,210,000	15,015,000
Signals and crossing equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	65,581,000	63,208,000
Accumulated depreciation	(22,408,000)	(16,746,000)
Property and equipment, net	43,173,000	46,462,000
Track equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	27,073,000	19,205,000
Accumulated depreciation	(9,019,000)	(7,277,000)
Property and equipment, net	18,054,000	11,928,000
Other equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	29,532,000	28,524,000
Accumulated depreciation	(16,017,000)	(13,800,000)
Property and equipment, net	13,515,000	14,724,000
Total equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	722,550,000	658,348,000
Accumulated depreciation	(232,078,000)	(189,446,000)
Property and equipment, net	490,472,000	468,902,000
Construction-in-process
Property, Plant and Equipment [Line Items]
Total property and equipment	42,974,000	30,395,000
Accumulated depreciation	0	0
Property and equipment, net	$ 42,974,000	$ 30,395,000

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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