Summary of Significant Accounting Policies Lessor Accounting (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term	5 years
Lessor, Operating Lease, Option to Terminate	1
Lessor, Direct Financing Lease, Description	0
Operating Lease, Lease Income, Lease Payments	$ 179.2
Operating Lease, Variable Lease Income	10.8
Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Operating Leases, Future Minimum Payments Receivable, Remainder of Fiscal Year	430.9
Operating Leases, Future Minimum Payments Receivable, in Two Years	478.3
Operating Leases, Future Minimum Payments Receivable, in Three Years	358.9
Operating Leases, Future Minimum Payments Receivable, in Four Years	267.2
Operating Leases, Future Minimum Payments Receivable, in Five Years	174.4
Operating Leases, Future Minimum Payments Receivable, Thereafter	312.8
Operating Leases, Future Minimum Payments Receivable	$ 2,022.5
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