Fair Value Disclosure (Details Textual) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended							3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2010 Railcar	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 Fair Value Hedging [Member] Instrument	Dec. 31, 2010 Fair Value Hedging [Member] Instrument	Sep. 30, 2011 Cash Flow Hedging [Member] Instrument	Dec. 31, 2010 Cash Flow Hedging [Member] Instrument	Sep. 30, 2011 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member] Impairment Losses [Member]	Sep. 30, 2010 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member] Impairment Losses [Member]	Sep. 30, 2011 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member] Impairment Losses [Member]	Sep. 30, 2010 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member] Impairment Losses [Member]	Sep. 30, 2011 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member] Impairment Losses [Member] Scrapped Wheelset [Member]	Sep. 30, 2010 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member] Impairment Losses [Member] Scrapped Wheelset [Member]	Sep. 30, 2011 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member] Impairment Losses [Member] Scrapped Wheelset [Member]	Sep. 30, 2010 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Nonrecurring [Member] Impairment Losses [Member] Scrapped Wheelset [Member]	Sep. 30, 2010 Regulatory Mandate [Member]
Derivative (Textual) [Abstract]
No. of instruments, outstanding					3	3	12	13
Maturity date range of fair value hedge derivatives					2012-2015		2012-2015
Additional Fair Value Disclosure (Textual) [Abstract]
Fair Value of Assets									$ 1.0	$ 0.4	$ 2.2	$ 5.8	$ 1.0	$ 0.4	$ 2.2	$ 1.0	$ 4.8
Fair Value Disclosure (Textual) [Abstract]
No. of Aluminum hopper railcars having economic life decreased	358
Aggregate notional amount of outstanding Fair value hedge derivative instruments			350.0	350.0
Aggregate notional amount of outstanding Cash flow hedge derivative instruments			78.0	130.4
Expected Pre tax reclassification of net losses from accumulated other comprehensive income to earnings in Next Twelve Months		7.1
Expected After tax reclassification of net losses from accumulated other comprehensive income to earnings in Next Twelve Months		4.5
Aggregate fair value of all derivative instruments with Net liability position			$ 3.0
Expected period for reclassification from Aoci to income			12 months