Summary of Significant Accounting Policies Lessee Accounting (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	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	10.8
Lessee, Operating Lease, Liability, Payments, Due Year Two	11.5
Lessee, Operating Lease, Liability, Payments, Due Year Three	10.6
Lessee, Operating Lease, Liability, Payments, Due Year Four	8.4
Lessee, Operating Lease, Liability, Payments, Due Year Five	4.0
Lessee, Operating Lease, Liability, Payments, Due after Year Five	4.7
Lessee, Operating Lease, Liability, Payments, Due	50.0
Lessee, Operating Lease, Lease not yet commenced, Amount	77.9
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(6.6)
Operating Leases, Rent Expense	3.9	$ 5.2
Short-term Lease, Cost	0.2	1.4
Operating Lease, Right-of-Use Asset	42.6	44.2
Operating Lease, Liability, Noncurrent	$ 43.4	$ 44.8
Operating Lease, Weighted Average Remaining Lease Term	4 years 7 months 6 days	4 years 9 months 18 days
Operating Lease, Weighted Average Discount Rate, Percent	4.10%	4.10%
Operating Lease, Payments	$ 3.9	$ 5.2
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 2.1	$ 0.0
Minimum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	40 years
Railcar Leasing and Management Services Group [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 7.8
Lessee, Operating Lease, Liability, Payments, Due Year Two	8.5
Lessee, Operating Lease, Liability, Payments, Due Year Three	7.8
Lessee, Operating Lease, Liability, Payments, Due Year Four	5.9
Lessee, Operating Lease, Liability, Payments, Due Year Five	2.7
Lessee, Operating Lease, Liability, Payments, Due after Year Five	1.8
Lessee, Operating Lease, Liability, Payments, Due	34.5
Consolidated Subsidiaries, Excluding Leasing [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	3.0
Lessee, Operating Lease, Liability, Payments, Due Year Two	3.0
Lessee, Operating Lease, Liability, Payments, Due Year Three	2.8
Lessee, Operating Lease, Liability, Payments, Due Year Four	2.5
Lessee, Operating Lease, Liability, Payments, Due Year Five	1.3
Lessee, Operating Lease, Liability, Payments, Due after Year Five	2.9
Lessee, Operating Lease, Liability, Payments, Due	$ 15.5