Long-term Debt (Details) $ in Thousands	Jun. 30, 2018 USD ($)
Summary of future contractual minimum rental revenues required under non-cancellable operating leases for railcars
Remaining 6 months of 2018	$ 65,698
2019	113,777
2020	76,330
2021	57,805
2022	38,206
2023 and thereafter	82,150
Total	433,966
Lease Fleet Financing [Member]
Summary of future contractual minimum rental revenues required under non-cancellable operating leases for railcars
Remaining 6 months of 2018	31,584
2019	50,005
2020	29,430
2021	18,890
2022	10,374
2023 and thereafter	10,482
Total	$ 150,765