Summary of Significant Accounting Policies Lessor Accounting (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 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		1 year
Direct Financing Lease, Revenue		$ 0.0
Operating Lease, Lease Income, Lease Payments	$ 169.5	506.9
Operating Lease, Variable Lease Income	12.5	36.6
Sales-type Lease, Revenue	26.3	60.5
Sales-type Lease, Interest Income	0.6	0.9
Sales-type Lease, Selling Profit (Loss)	3.7	7.8
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Remainder of Fiscal Year	4.6	4.6
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Two Years	15.7	15.7
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years	45.9	45.9
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Four Years	0.0	0.0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Five Years	0.0	0.0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Thereafter	0.0	0.0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received	66.2	66.2
Sales-type and Direct Financing Leases, Lease Receivable, Undiscounted Excess Amount	(7.8)	(7.8)
Sales-type Lease, Net Investment in Lease	58.4	58.4
Net Investment in Lease, Current	0.9	0.9
Net Investment in Lease, Noncurrent	57.5	57.5
Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Operating Leases, Future Minimum Payments Receivable, Remainder of Fiscal Year	149.4	149.4
Operating Leases, Future Minimum Payments Receivable, in Two Years	521.3	521.3
Operating Leases, Future Minimum Payments Receivable, in Three Years	413.0	413.0
Operating Leases, Future Minimum Payments Receivable, in Four Years	314.8	314.8
Operating Leases, Future Minimum Payments Receivable, in Five Years	217.1	217.1
Operating Leases, Future Minimum Payments Receivable, Thereafter	388.2	388.2
Operating Leases, Future Minimum Payments Receivable	$ 2,003.8	$ 2,003.8
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