Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
VIE for Rail	$ 6,855.2	$ 6,416.0
VIE depreciation allowance	2,200.8	2,056.7
VIE nonrecourse debt	130.6	149.4
Common stock, par value	$ 0.625	$ 0.625
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	66,021,444	65,775,568
Common stock, shares outstanding	46,898,924	46,653,048
Treasury stock, shares outstanding	19,122,520	19,122,520
Preferred stock, aggregate liquidation preference	0.9	1.0
Series A and B $2.50 Cumulative Convertible Preferred Stock [Member]
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	15,567	16,644
Preferred stock, shares outstanding	15,567	16,644
Preferred stock, aggregate liquidation preference	0.9	1.0
Cumulative annual cash dividend per share on preferred stock	$ 2.50	$ 2.5
Variable Interest Entity, Primary Beneficiary [Member]
VIE for Rail	123.1	123.5
VIE depreciation allowance	24.7	19.2
VIE nonrecourse debt	$ 35.1	$ 45.2