Summary of Significant Accounting Policies Lessee Accounting (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term		5 years		5 years
Lessee, Operating Lease, Option to Terminate				one year
Finance Lease, Principal Payments				$ 0.0
Operating lease expense		$ 4.7	$ 3.8	8.9	$ 7.3
Short-term lease expense		0.1	$ 0.2	0.2	0.2
Right-of-use assets (1)	[1]	90.8		90.8		$ 82.8
Lease liabilities (2)	[2]	$ 113.6		$ 113.6		$ 106.3
Weighted average remaining lease term		10 years 1 month 6 days		10 years 1 month 6 days		10 years 9 months 18 days
Weighted average discount rate		2.80%		2.80%		3.00%
Cash flows from operating activities				$ 8.9	7.3
Right-of-use assets recognized in exchange for new lease liabilities				17.8	$ 19.7
Remaining six months of 2022		$ 10.7		10.7
2023		19.2		19.2
2024		14.2		14.2
2025		11.4		11.4
2026		10.7		10.7
Thereafter		66.0		66.0
Lessee, Operating Lease, Liability, to be Paid, Total		132.2		132.2
Less: Present value adjustment		$ (18.6)		$ (18.6)
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		15 years		15 years
Railcar Leasing and Management Services Group [Member]
Lessee, Lease, Description [Line Items]
Remaining six months of 2022		$ 6.6		$ 6.6
2023		11.4		11.4
2024		7.5		7.5
2025		5.4		5.4
2026		5.1		5.1
Thereafter		8.2		8.2
Lessee, Operating Lease, Liability, to be Paid, Total		44.2		44.2
Consolidated Subsidiaries, Excluding Leasing [Member]
Lessee, Lease, Description [Line Items]
Remaining six months of 2022		4.1		4.1
2023		7.8		7.8
2024		6.7		6.7
2025		6.0		6.0
2026		5.6		5.6
Thereafter		57.8		57.8
Lessee, Operating Lease, Liability, to be Paid, Total		$ 88.0		$ 88.0

[1] Included in other assets in our Consolidated Balance Sheets.

[2] Included in other liabilities in our Consolidated Balance Sheets.