Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
VIE for Rail	$ 5,692.6	$ 5,513.6
VIE depreciation allowance	2,056.7	2,049.7
VIE nonrecourse debt	149.4	217.2
Common stock, par value	$ 0.625	$ 0.625
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	65,775,568	65,482,950
Common stock, shares outstanding	46,653,048	46,360,430
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	16,694
Preferred stock, shares outstanding	16,644	16,694
Preferred stock, aggregate liquidation preference	1.0	1.0
Variable Interest Entity, Primary Beneficiary [Member]
VIE for Rail	123.5	123.7
VIE depreciation allowance	19.2	13.6
VIE nonrecourse debt	$ 45.2	$ 56.2