Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
VIE for Rail	$ 5,843.1	$ 5,692.6
VIE depreciation allowance	2,107.5	2,056.7
VIE nonrecourse debt	146.3	149.4
Common stock, par value	$ 0.625	$ 0.625
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	65,953,349	65,775,568
Common stock, shares outstanding	46,830,829	46,653,048
Treasury stock, shares outstanding	19,122,520	19,122,520
Series A and B $2.50 Cumulative Convertible Preferred Stock [Member]
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	16,644	16,644
Preferred stock, shares outstanding	16,644	16,644
Preferred stock, aggregate liquidation preference	1.0	1.0
Variable Interest Entity, Primary Beneficiary [Member]
VIE for Rail	123.2	123.5
VIE depreciation allowance	20.5	19.2
VIE nonrecourse debt	$ 42.4	$ 45.2