Summary of Significant Accounting Policies Lessee Accounting (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
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		5.3	$ 4.3
Cash flows from operating activities		5.3	4.3
Right-of-use assets recognized in exchange for new lease liabilities		4.2	$ 2.1
Right-of-use assets (1)	[1]	100.9		$ 100.6
Lease liabilities (2)	[2]	$ 118.0		$ 118.2
Weighted average remaining lease term		9 years 1 month 6 days		9 years 3 months 18 days
Weighted average discount rate (3)	[3]	3.70%		3.60%
Remaining nine months of 2024		$ 15.7
2025		18.9
2026		17.2
2027		16.0
2028		12.5
Thereafter		58.3
Lessee, Operating Lease, Liability, to be Paid, Total		138.6
Less: Present value adjustment		(20.6)
Railcars on Lease [Member]
Lessee, Lease, Description [Line Items]
Remaining nine months of 2024		6.6
2025		8.2
2026		7.7
2027		7.2
2028		5.1
Thereafter		6.8
Lessee, Operating Lease, Liability, to be Paid, Total		41.6
Operating & Administrative Assets [Member]
Lessee, Lease, Description [Line Items]
Remaining nine months of 2024		9.1
2025		10.7
2026		9.5
2027		8.8
2028		7.4
Thereafter		51.5
Lessee, Operating Lease, Liability, to be Paid, Total		$ 97.0
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		13 years

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

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

[3] As the rate implicit in our leases is not readily determinable, we use the incremental borrowing rate of our Trinity Industries Leasing Company ("TILC") warehouse loan facility for railcar leases or our revolving credit facility for operating and administrative leases at lease commencement to determine the present value of lease payments.