Subsequent Events (Details) (RailAmerica [Member], USD $) Share data in Millions, except Per Share data, unless otherwise specified	Jul. 17, 2012
Subsequent Event [Line Items]
Purchase price per share	$ 27.50
Cash purchase price	$ 1,400,000,000
Diluted shares outstanding of acquired entity	50.8
Net debt acquired	600,000,000
Expected new debt from refinancing and funding acquisition	2,000,000,000
Expected equity or equity linked securities to fund acquisition	800,000,000
Committed new debt financing from BOAML	2,300,000,000
Additional issuance of equity or equity-linked securities	450,000,000
Termination fee	49,000,000
Reverse termination fee	135,000,000
The Carlyle Group [Member]
Subsequent Event [Line Items]
Committed equity financing from Carlyle	800,000,000
Minimum private placement of mandatorily convertible preferred stock	350,000,000
Convertible preferred stock coupon rate	5.00%
Preferred Stock, Redemption Amount	58.49
Additional private placement of manditorily convertible preferred stock	$ 450,000,000