Summary of Significant Accounting Policies Lessor Accounting (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term		5 years
Direct Financing Lease, Revenue		$ 0.0
Operating lease revenues		191.8	$ 176.7
Variable operating lease revenues		13.7	14.6
Interest income on sales-type lease receivables		0.2	$ 0.2
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Remainder of Fiscal Year		0.8
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Two		1.1
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		1.1
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		1.1
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		1.1
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		9.0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		14.2
Less: Unearned interest income		(4.1)
Net investment in sales-type leases (1)	[1]	10.1
Railcar Leasing and Services Group [Member]
Lessor, Lease, Description [Line Items]
Remaining nine months of 2024	[2]	530.2
2025	[2]	593.8
2026	[2]	472.1
2027	[2]	350.4
2028	[2]	211.4
Thereafter	[2]	331.7
Total	[2]	$ 2,489.6
Minimum | Railcar Leasing and Services Group [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract		1 year
Maximum | Railcar Leasing and Services Group [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract		10 years

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

[2] Total contractual minimum rental revenues on operating leases relates to our wholly-owned and partially-owned subsidiaries and sub-lease rental revenues associated with the Leasing Group's operating lease obligations.