Related Party Transactions (Details) (USD $)	12 Months Ended		0 Months Ended	12 Months Ended			9 Months Ended
	Dec. 31, 2010	Dec. 31, 2009	Oct. 29, 2010	Dec. 31, 2014 facility	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2003	Dec. 31, 2003
Related Party Transaction [Line Items]
Inventory of railcar components purchased from joint ventures				$ 117,007,000	$ 90,185,000
Ohio Castings [Member]
Related Party Transaction [Line Items]
Amount loaned under promissory note								3,000,000
Axis [Member]
Related Party Transaction [Line Items]
Revenue from related parties	300,000
Service agreement period	1 year
Service Agreement Renewal Period	1 year
Company's Interest in credit facility, Axis		50.00%
ARI Headquarters Lease [Member]
Related Party Transaction [Line Items]
Expense with related party/Total fees paid				600,000	600,000	600,000
Lessee Leasing Arrangements, Operating Leases, Term of Contract			11 years
Property Subject to or Available for Operating Lease, Number of Units				1
Related Party Parts Facility [Member]
Related Party Transaction [Line Items]
Expense with related party/Total fees paid				400,000	400,000	400,000
Term Loan and Credit Agreement [Member] | Axis [Member]
Related Party Transaction [Line Items]
Notes receivable				29,100,000	32,900,000
Revised Ohio Castings Agreement [Member] | Ohio Castings [Member]
Related Party Transaction [Line Items]
Note renegotiated principal amount									2,200,000
ACF [Member] | Manufacturing Services Agreement [Member] | Maximum [Member]
Related Party Transaction [Line Items]
Assets purchased from ACF				5,100,000	300,000	100,000
Other Related Party [Member] | Revised Ohio Castings Agreement [Member]
Related Party Transaction [Line Items]
Interest rate						4.00%
M.W. Recycling [Member]
Related Party Transaction [Line Items]
Revenue from related parties				8,700,000	7,400,000	8,600,000
Insight Portfolio [Member]
Related Party Transaction [Line Items]
Expense with related party/Total fees paid				200,000	200,000
Joint Ventures [Member]
Related Party Transaction [Line Items]
Expense with related party/Total fees paid				127,700,000	89,300,000	83,500,000
Inventory of railcar components purchased from joint ventures				6,600,000	6,200,000
ARL [Member] | Railcar services agreement [Member]
Related Party Transaction [Line Items]
Revenue from related parties				19,300,000	17,200,000	21,400,000
Service agreement period				3 years
Service Agreement Renewal Period				1 year
ARL [Member] | Railcar management agreement [Member]
Related Party Transaction [Line Items]
Expense with related party/Total fees paid				5,100,000	2,300,000	1,400,000
Total sales commission				600,000	400,000	0
Director [Member]
Related Party Transaction [Line Items]
Noninterest Expense Directors Fees							65,000
Purchasing and Engineering Services Agreement [Member] | ACF [Member]
Related Party Transaction [Line Items]
Revenue As Percentage of Profit Under Agreement				30.00%
Revenue from related parties				19,000,000	12,300,000
Railcar Orders [Member] | IELP Entities [Member]
Related Party Transaction [Line Items]
Revenue from related parties				$ 226,900,000	$ 238,200,000	$ 103,600,000