Summary of Significant Accounting Policies Lessee Accounting (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 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 lease expense		$ 3.7	$ 4.0	12.2	$ 13.3
Short-term lease expense		0.7	$ 0.9	2.1	3.5
Right-of-use assets (1)	[1]	77.0		77.0		$ 44.2
Lease liabilities (2)	[2]	$ 89.9		$ 89.9		$ 44.8
Weighted average remaining lease term		11 years 2 months 12 days		11 years 2 months 12 days		4 years 9 months 18 days
Weighted average discount rate		3.40%		3.40%		4.10%
Cash flows from operating activities				$ 12.2	13.3
Right-of-use assets recognized in exchange for new lease liabilities (3)	[3]			53.6	$ 8.4
Remaining three months of 2020		$ 3.3		3.3
2021		12.1		12.1
2022		15.2		15.2
2023		13.5		13.5
2024		9.2		9.2
Thereafter		70.0		70.0
Total operating lease payments		123.3		123.3
Less: Present value adjustment		(23.7)		(23.7)
Less: Lease incentives		$ (9.7)		$ (9.7)
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]
Remaining three months of 2020		$ 2.2		$ 2.2
2021		8.6		8.6
2022		7.8		7.8
2023		6.0		6.0
2024		2.9		2.9
Thereafter		1.5		1.5
Total operating lease payments		29.0		29.0
Consolidated Subsidiaries, Excluding Leasing [Member]
Lessee, Lease, Description [Line Items]
Remaining three months of 2020		1.1		1.1
2021		3.5		3.5
2022		7.4		7.4
2023		7.5		7.5
2024		6.3		6.3
Thereafter		68.5		68.5
Total operating lease payments		$ 94.3		$ 94.3

[1] (Mark One)

[2] (Mark One)

[3] (Mark One)