Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
VIE for Rail	$ 8,143.5us-gaap_PropertyPlantAndEquipmentGross	$ 7,390.7us-gaap_PropertyPlantAndEquipmentGross
VIE depreciation allowance	2,455.5	2,320.4
VIE nonrecourse debt	15.9us-gaap_NonRecourseDebt	72.6us-gaap_NonRecourseDebt
Common stock, par value	$ 0.625	$ 0.625
Common stock, shares authorized	120,000,000us-gaap_CommonStockSharesAuthorized	120,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	66,600,984us-gaap_CommonStockSharesIssued	66,349,906us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	44,198,850us-gaap_CommonStockSharesOutstanding	45,868,698us-gaap_CommonStockSharesOutstanding
Treasury stock, shares outstanding	22,402,134us-gaap_TreasuryStockShares	20,118,120us-gaap_TreasuryStockShares
Variable Interest Entity, Primary Beneficiary [Member]
VIE for Rail	123.1	123.3
VIE depreciation allowance	35.0	30.3
VIE nonrecourse debt	$ 15.9	$ 25.4

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

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