Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
VIE for Rail	$ 8,204.0	$ 8,143.5
VIE depreciation allowance	2,505.6	2,455.5
VIE nonrecourse debt	$ 6.9	$ 15.9
Common stock, par value	$ 0.625	$ 0.625
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	66,776,290.000000	66,600,984
Common stock, shares outstanding	41,970,098	44,198,850
Treasury stock, shares outstanding	24,806,192	22,402,134
Variable Interest Entity, Primary Beneficiary [Member]
VIE for Rail	$ 122.9	$ 123.1
VIE depreciation allowance	39.7	35.0
VIE nonrecourse debt	$ 6.9	$ 15.9