Summary of Significant Accounting Policies Lessee Accounting (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
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		$ 4.4	$ 4.7	8.7	$ 8.9
Short-term lease expense		0.0	$ 0.1	0.0	0.2
Cash flows from operating activities				8.7	8.9
Right-of-use assets recognized in exchange for new lease liabilities				6.4	$ 17.8
Right-of-use assets (1)	[1]	92.1		92.1		$ 93.1
Lease liabilities (2)	[2]	$ 110.8		$ 110.8		$ 114.8
Weighted average remaining lease term		9 years 8 months 12 days		9 years 8 months 12 days		9 years 10 months 24 days
Weighted average discount rate		3.00%		3.00%		2.80%
Remaining six months of 2023		$ 10.4		$ 10.4
2024		16.1		16.1
2025		14.3		14.3
2026		13.4		13.4
2027		12.7		12.7
Thereafter		61.5		61.5
Lessee, Operating Lease, Liability, to be Paid, Total		128.4		128.4
Less: Present value adjustment		$ (17.6)		$ (17.6)
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		14 years		14 years
Railcar Leasing and Management Services Group [Member]
Lessee, Lease, Description [Line Items]
Remaining six months of 2023		$ 5.4		$ 5.4
2024		7.1		7.1
2025		6.2		6.2
2026		5.8		5.8
2027		5.3		5.3
Thereafter		3.7		3.7
Lessee, Operating Lease, Liability, to be Paid, Total		33.5		33.5
Consolidated Subsidiaries, Excluding Leasing [Member]
Lessee, Lease, Description [Line Items]
Remaining six months of 2023		5.0		5.0
2024		9.0		9.0
2025		8.1		8.1
2026		7.6		7.6
2027		7.4		7.4
Thereafter		57.8		57.8
Lessee, Operating Lease, Liability, to be Paid, Total		$ 94.9		$ 94.9

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

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