Summary of Significant Accounting Policies Lessee Accounting (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term		5 years
Lessee, Operating Lease, Option to Terminate		one year
Finance Lease, Principal Payments		$ 0.0
Operating lease expense		4.2	$ 3.5
Short-term lease expense		0.1	0.0
Right-of-use assets (1)	[1]	88.5		$ 82.8
Lease liabilities (2)	[2]	$ 112.3		$ 106.3
Weighted average remaining lease term		10 years 4 months 24 days		10 years 9 months 18 days
Weighted average discount rate		2.90%		3.00%
Cash flows from operating activities		$ 4.2	3.5
Right-of-use assets recognized in exchange for new lease liabilities		11.1	$ 11.0
Remaining nine months of 2022		14.9
2023		17.7
2024		13.3
2025		10.8
2026		10.1
Thereafter		64.3
Lessee, Operating Lease, Liability, to be Paid, Total		131.1
Less: Present value adjustment		$ (18.8)
Minimum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract		1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract		15 years
Railcar Leasing and Management Services Group [Member]
Lessee, Lease, Description [Line Items]
Remaining nine months of 2022		$ 9.2
2023		10.5
2024		7.0
2025		5.2
2026		4.9
Thereafter		7.6
Lessee, Operating Lease, Liability, to be Paid, Total		44.4
Consolidated Subsidiaries, Excluding Leasing [Member]
Lessee, Lease, Description [Line Items]
Remaining nine months of 2022		5.7
2023		7.2
2024		6.3
2025		5.6
2026		5.2
Thereafter		56.7
Lessee, Operating Lease, Liability, to be Paid, Total		$ 86.7

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

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