Long-term Debt (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Summary of future contractual minimum rental revenues required under non-cancellable operating leases for railcars
Remaining 6 months of 2013	$ 15,516
2014	29,409
2015	28,735
2016	27,946
2017	20,837
2018	12,579
2019 and thereafter	23,970
Total	158,992
Lease Fleet Financing [Member]
Summary of future contractual minimum rental revenues required under non-cancellable operating leases for railcars
Remaining 6 months of 2013	12,446
2014	24,892
2015	24,549
2016	23,761
2017	16,651
2018	9,023
2019 and thereafter	17,462
Total	$ 128,784