Summary of Significant Accounting Policies Lessor Accounting (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2018
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term	5 years
Lessor, Operating Lease, Termination Option Term	1 year
Sales-type Lease, Revenue	$ 0.0
Direct Financing Lease, Revenue	0.0
Operating Lease, Lease Income, Lease Payments	172.2	$ 179.2
Operating Lease, Variable Lease Income	12.6	10.8
Sales-type Lease, Interest Income	1.7	$ 0.0
Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Operating Leases, Future Minimum Payments Receivable, Remainder of Fiscal Year	446.5
Operating Leases, Future Minimum Payments Receivable, in Two Years	482.1
Operating Leases, Future Minimum Payments Receivable, in Three Years	376.3
Operating Leases, Future Minimum Payments Receivable, in Four Years	268.8
Operating Leases, Future Minimum Payments Receivable, in Five Years	183.7
Operating Leases, Future Minimum Payments Receivable, Thereafter	330.8
Operating Leases, Future Minimum Payments Receivable	$ 2,088.2
Minimum | Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract	1 year
Maximum | Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract	10 years		20 years