Derivative Financial Instruments Contingent Forward Sale Contract (Details) (USD $)	2 Months Ended	12 Months Ended			0 Months Ended
	Sep. 28, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Oct. 02, 2012	Jul. 23, 2012
Derivatives [Line Items]
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
Not Designated as Hedging Instrument [Member]
Derivatives [Line Items]
Contingent forward sale contract mark-to-market expense				50,100,000
Series A-1 Preferred Stock [Member]
Derivatives [Line Items]
Net proceeds from Series A-1 Preferred Stock issuance				349,400,000
Preferred Stock conversion price						58.49
Premium on conversion price						4.50%
Series A-1 Preferred Stock [Member] | The Carlyle Group [Member] | Financing of RailAmerica acquisition [Member]
Derivatives [Line Items]
Net proceeds from Series A-1 Preferred Stock issuance					$ 350,000,000
Class A Common Stock [Member]
Derivatives [Line Items]
Share price	$ 66.86