Summary of Significant Accounting Policies Lessee Accounting (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	5 years	5 years
Lessee, Operating Lease, Termination Option Term		1 year
Finance Lease, Principal Payments		$ 0.0
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 4.1	4.1
Lessee, Operating Lease, Liability, Payments, Due Year Two	12.6	12.6
Lessee, Operating Lease, Liability, Payments, Due Year Three	10.3	10.3
Lessee, Operating Lease, Liability, Payments, Due Year Four	9.3	9.3
Lessee, Operating Lease, Liability, Payments, Due Year Five	7.0	7.0
Lessee, Operating Lease, Liability, Payments, Due after Year Five	6.6	6.6
Lessee, Operating Lease, Liability, Payments, Due	49.9	49.9
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(3.9)	(3.9)
Operating Leases, Rent Expense	4.0	13.3
Short-term Lease, Cost	0.9	3.5
Operating Lease, Right-of-Use Asset	45.3	45.3
Operating Lease, Liability, Noncurrent	$ 46.0	$ 46.0
Operating Lease, Weighted Average Remaining Lease Term	4 years 10 months 24 days	4 years 10 months 24 days
Operating Lease, Weighted Average Discount Rate, Percent	4.10%	4.10%
Operating Lease, Payments		$ 13.3
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		$ 8.4
Minimum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	1 year	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	40 years	40 years
Railcar Leasing and Management Services Group [Member]
Lessee, Lease, Description [Line Items]
Minimum Lease Payments, Sale Leaseback Transactions, Remainder of Fiscal Year	$ 3.2	$ 3.2
Minimum Lease Payments, Sale Leaseback Transactions, within Two Years	9.5	9.5
Minimum Lease Payments, Sale Leaseback Transactions, within Three Years	8.2	8.2
Minimum Lease Payments, Sale Leaseback Transactions, within Four Years	7.5	7.5
Minimum Lease Payments, Sale Leaseback Transactions, within Five Years	5.5	5.5
Minimum Lease Payments, Sale Leaseback Transactions, Thereafter	3.3	3.3
Minimum Lease Payments, Sale Leaseback Transactions	37.2	37.2
Consolidated Subsidiaries, Excluding Leasing [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	0.9	0.9
Lessee, Operating Lease, Liability, Payments, Due Year Two	3.1	3.1
Lessee, Operating Lease, Liability, Payments, Due Year Three	2.1	2.1
Lessee, Operating Lease, Liability, Payments, Due Year Four	1.8	1.8
Lessee, Operating Lease, Liability, Payments, Due Year Five	1.5	1.5
Lessee, Operating Lease, Liability, Payments, Due after Year Five	3.3	3.3
Lessee, Operating Lease, Liability, Payments, Due	$ 12.7	$ 12.7