Summary of Significant Accounting Policies Lessee Accounting (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 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		$ 4.6	$ 4.6	13.3	$ 13.5
Short-term lease expense		0.0	$ 0.1	0.0	0.3
Cash flows from operating activities				13.3	13.5
Right-of-use assets recognized in exchange for new lease liabilities				9.6	$ 21.0
Right-of-use assets (1)	[1]	91.1		91.1		$ 93.1
Lease liabilities (2)	[2]	$ 109.5		$ 109.5		$ 114.8
Weighted average remaining lease term		9 years 7 months 6 days		9 years 7 months 6 days		9 years 10 months 24 days
Weighted average discount rate		3.10%		3.10%		2.80%
Remaining three months of 2023		$ 5.3		$ 5.3
2024		16.9		16.9
2025		15.0		15.0
2026		13.9		13.9
2027		13.4		13.4
Thereafter		62.5		62.5
Lessee, Operating Lease, Liability, to be Paid, Total		127.0		127.0
Less: Present value adjustment		$ (17.5)		$ (17.5)
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 three months of 2023		$ 2.7		$ 2.7
2024		7.2		7.2
2025		6.3		6.3
2026		5.9		5.9
2027		5.5		5.5
Thereafter		3.9		3.9
Lessee, Operating Lease, Liability, to be Paid, Total		31.5		31.5
Consolidated Subsidiaries, Excluding Leasing [Member]
Lessee, Lease, Description [Line Items]
Remaining three months of 2023		2.6		2.6
2024		9.7		9.7
2025		8.7		8.7
2026		8.0		8.0
2027		7.9		7.9
Thereafter		58.6		58.6
Lessee, Operating Lease, Liability, to be Paid, Total		$ 95.5		$ 95.5

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

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