Leases (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) tankContainer railcar	Dec. 31, 2020 USD ($) tankContainer	Dec. 31, 2019 USD ($) tankContainer
Operating Leased Assets [Line Items]
Number of railcars received | tankContainer	2,329	732	157
Lessee, Lease, Number of Railcars Leased | railcar	5,200
Direct Financing Lease, Lease Income	$ 7.0	$ 7.2	$ 9.8
Operating Lease, Lease Income, Lease Payments	1,063.4	1,020.9	1,013.5
Operating Lease, Variable Lease Income	70.1	59.4	65.2
Operating Lease, Lease Income	1,133.5	1,080.3	1,078.7
Lease Income	1,140.5	1,087.5	$ 1,088.5
Total contractual lease payments receivable	106.9	77.1
Estimated unguaranteed residual value of leased assets	20.0	24.6
Unearned income	(26.7)	(27.7)
Finance leases	$ 100.2	$ 74.0