Summary of Significant Accounting Policies Lessee Accounting (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	5 years		5 years
Lessee, Operating Lease, Termination Option Term			one year
Finance Lease, Principal Payments			$ 0.0
Operating Leases, Rent Expense	$ 4.6	$ 4.1	8.5	$ 9.3
Short-term Lease, Cost	1.2	$ 1.2	1.4	2.6
Operating Lease, Right-of-Use Asset	77.2		77.2		$ 44.2
Operating Lease, Liability, Noncurrent	$ 89.2		$ 89.2		$ 44.8
Operating Lease, Weighted Average Remaining Lease Term	11 years		11 years		4 years 9 months 18 days
Operating Lease, Weighted Average Discount Rate, Percent	3.40%		3.40%		4.10%
Operating Lease, Payments			$ 8.5	9.3
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability			50.7	$ 4.2
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 6.9		6.9
Lessee, Operating Lease, Liability, Payments, Due Year Two	11.6		11.6
Lessee, Operating Lease, Liability, Payments, Due Year Three	14.7		14.7
Lessee, Operating Lease, Liability, Payments, Due Year Four	12.9		12.9
Lessee, Operating Lease, Liability, Payments, Due Year Five	8.6		8.6
Lessee, Operating Lease, Liability, Payments, Due after Year Five	69.1		69.1
Lessee, Operating Lease, Liability, Payments, Due	123.8		123.8
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(23.0)		(23.0)
Lease Incentive Receivable	$ (11.6)		$ (11.6)
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	16 years		16 years
Railcar Leasing and Management Services Group [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 4.9		$ 4.9
Lessee, Operating Lease, Liability, Payments, Due Year Two	8.5		8.5
Lessee, Operating Lease, Liability, Payments, Due Year Three	7.8		7.8
Lessee, Operating Lease, Liability, Payments, Due Year Four	5.9		5.9
Lessee, Operating Lease, Liability, Payments, Due Year Five	2.7		2.7
Lessee, Operating Lease, Liability, Payments, Due after Year Five	1.5		1.5
Lessee, Operating Lease, Liability, Payments, Due	31.3		31.3
Consolidated Subsidiaries, Excluding Leasing [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	2.0		2.0
Lessee, Operating Lease, Liability, Payments, Due Year Two	3.1		3.1
Lessee, Operating Lease, Liability, Payments, Due Year Three	6.9		6.9
Lessee, Operating Lease, Liability, Payments, Due Year Four	7.0		7.0
Lessee, Operating Lease, Liability, Payments, Due Year Five	5.9		5.9
Lessee, Operating Lease, Liability, Payments, Due after Year Five	67.6		67.6
Lessee, Operating Lease, Liability, Payments, Due	$ 92.5		$ 92.5