Leases (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) railcar	Dec. 31, 2019 USD ($) railcar	Dec. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
2023	$ 8.4
Repayments of Long-term Capital Lease Obligations	$ (40.0)	$ (11.3)	$ 0.0
Number of railcars received | railcar	732	157
Lessee, Lease, Number of Railcars Leased | railcar	6,700
Direct Financing Lease, Lease Income	$ 7.2	$ 9.8
Operating Lease, Lease Income, Lease Payments	1,020.9	1,013.5
Operating Lease, Variable Lease Income	59.4	65.2
Operating Lease, Lease Income	1,080.3	1,078.7
Lease Income	1,087.5	1,088.5	$ 1,083.7
Total contractual lease payments receivable	77.1	84.4
Estimated unguaranteed residual value of leased assets	24.6	40.7
Unearned income	(27.7)	(34.8)
Finance leases	$ 74.0	$ 90.3