Changes in Operations United States RailAmerica (Details) (USD $)	0 Months Ended		2 Months Ended	3 Months Ended			12 Months Ended			0 Months Ended		3 Months Ended
	May 31, 2014	Oct. 02, 2012	Sep. 28, 2012	Dec. 31, 2013	Sep. 30, 2013	Mar. 31, 2013	Dec. 31, 2014 employee	Dec. 31, 2013	Dec. 31, 2012	Feb. 13, 2013	Sep. 19, 2012	Dec. 28, 2012	Oct. 01, 2012
Business Acquisition [Line Items]
Business Acquisition, Name of Acquired Entity	Rapid City, Pierre & Eastern Railroad, Inc. (RCP&E)	RailAmerica, Inc.
Net proceeds from Series A-1 Preferred Stock issuance							$ 0	$ 0	$ 349,418,000
Contingent forward sale contract mark-to-market expense			50,100,000				0	0	50,106,000
Income from equity investment in RailAmerica, net							0	0	15,557,000
RailAmerica integration and acquisition-related costs, net of tax				600,000	1,300,000	8,000,000
Number of employees acquired							5,200
Series A-1 Preferred Stock [Member]
Business Acquisition [Line Items]
Net proceeds from Series A-1 Preferred Stock issuance									349,400,000
Class A Common Stock [Member]
Business Acquisition [Line Items]
Common Stock, Shares, Outstanding				51,934,137			52,938,267	51,934,137
Conversion of shares to Class A Common Stock, shares										5,984,232
Combined Company including G&W and RailAmerica [Member]
Business Acquisition [Line Items]
Acquisition refinancing of debt		1,200,000,000
RailAmerica [Member]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired		100.00%
Cash purchase price per share		27.50
Common Stock, Shares, Outstanding		49,934,000
Cash consideration		2,032,382,000
Impact of pre-acquisition share-based awards		9,400,000
Total consideration		2,041,782,000
Business Combination, Integration Related Costs								17,000,000	30,000,000
Number of employees acquired		2,000
Number of railroads acquired		45
Track miles acquired		7,100
Number of states in which entity operates		28
Number of provinces in which entity operates		3
RailAmerica [Member] | Equity Purchase Price [Member]
Business Acquisition [Line Items]
Cash consideration		1,373,184,000
RailAmerica [Member] | Payment of acquiree's debt [Member]
Business Acquisition [Line Items]
Cash consideration		659,198,000
Financing of RailAmerica acquisition [Member]
Business Acquisition [Line Items]
Acquisition refinancing of debt													1,900,000,000
Financing of RailAmerica acquisition [Member] | Common stock and TEUs [Member]
Business Acquisition [Line Items]
Proceeds from issuance of common stock and TEUs											475,500,000
Financing of RailAmerica acquisition [Member] | Series A-1 Preferred Stock [Member] | The Carlyle Group [Member]
Business Acquisition [Line Items]
Net proceeds from Series A-1 Preferred Stock issuance		350,000,000
RailAmerica [Member]
Business Acquisition [Line Items]
Income from equity investment in RailAmerica, net												15,600,000
RailAmerica integration and acquisition-related costs, net of tax												$ 3,500,000