Summary of Significant Accounting Policies Lessor Accounting (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2018
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term	5 years		5 years
Lessor, Operating Lease, Termination Option Term			one year
Direct Financing Lease, Revenue	$ 0.0		$ 0.0
Operating Lease, Lease Income, Lease Payments	165.1	$ 171.6	337.3	$ 339.9
Operating Lease, Variable Lease Income	10.6	10.8	23.2	21.6
Sales-type Lease, Revenue	0.0	32.3	0.0	34.2
Sales-type Lease, Interest Income	0.0	0.3	0.0	0.3
Sales-type Lease, Selling Profit (Loss)	0.0	$ 3.9	0.0	$ 4.1
Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Operating Leases, Future Minimum Payments Receivable, Remainder of Fiscal Year	298.6		298.6
Operating Leases, Future Minimum Payments Receivable, in Two Years	494.0		494.0
Operating Leases, Future Minimum Payments Receivable, in Three Years	387.9		387.9
Operating Leases, Future Minimum Payments Receivable, in Four Years	280.9		280.9
Operating Leases, Future Minimum Payments Receivable, in Five Years	199.8		199.8
Operating Leases, Future Minimum Payments Receivable, Thereafter	353.8		353.8
Operating Leases, Future Minimum Payments Receivable	$ 2,015.0		$ 2,015.0
Minimum | Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract	1 year		1 year
Maximum | Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract	10 years		10 years		20 years