Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Effective income tax rate	36.80%	33.70%	37.20%	34.80%
Tax benefit from change in tax accounting methods for companies acquired from RailAmerica	$ 3.9			$ 3.9
RCP&E [Member]
Tax benefit from adjusting deferred income taxes to reflect impact of RCP&E acquisition				$ 1.0