Summary of Significant Accounting Policies Lessor Accounting (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term		5 years		5 years
Direct Financing Lease, Revenue				$ 0.0
Operating lease revenues		$ 183.4	$ 167.2	542.0	$ 500.5
Variable operating lease revenues		18.3	17.7	51.0	49.0
Interest income on sales-type lease receivables		0.1	0.2	0.5	0.5
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Remainder of Fiscal Year		0.3		0.3
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Two		1.1		1.1
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Three		1.1		1.1
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Four		1.1		1.1
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year Five		1.1		1.1
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, after Year Five		10.1		10.1
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		14.8		14.8
Less: Unearned interest income		(4.5)		(4.5)
Net investment in sales-type leases (1)	[1]	10.3		10.3
Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Remaining three months of 2023	[2]	176.3		176.3
2024	[2]	622.6		622.6
2025	[2]	506.0		506.0
2026	[2]	387.4		387.4
2027	[2]	282.2		282.2
Thereafter	[2]	434.3		434.3
Total	[2]	2,408.8		2,408.8
Railcar Leasing and Management Services Group [Member] | Operating Segments [Member] | Sales of Leased Railcars [Domain]
Lessor, Lease, Description [Line Items]
Profit recognized at sales-type lease commencement (1)	[3]	$ 0.0	$ 0.0	$ 0.0	$ 1.3
Minimum | Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract		1 year		1 year
Maximum | Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract		10 years		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.

[3] Included in gains on dispositions of property – lease portfolio sales on our Consolidated Statements of Operations.