Summary of Significant Accounting Policies Lessor Accounting (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term		5 years		5 years
Direct Financing Lease, Revenue				$ 0.0
Operating lease revenues		$ 196.0	$ 181.9	387.8	$ 358.6
Variable operating lease revenues		20.8	18.1	34.5	32.7
Interest income on sales-type lease receivables		0.1	$ 0.2	0.3	$ 0.4
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Remainder of Fiscal Year		0.6		0.6
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		9.0		9.0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received		14.0		14.0
Less: Unearned interest income		(4.0)		(4.0)
Net investment in sales-type leases (1)	[1]	10.0		10.0
Railcar Leasing and Services Group [Member]
Lessor, Lease, Description [Line Items]
Remaining six months of 2024	[2]	362.9		362.9
2025	[2]	623.5		623.5
2026	[2]	503.0		503.0
2027	[2]	377.9		377.9
2028	[2]	236.1		236.1
Thereafter	[2]	345.9		345.9
Total	[2]	$ 2,449.3		$ 2,449.3
Minimum | Railcar Leasing and Services Group [Member]
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Term of Contract		1 year		1 year
Maximum | Railcar Leasing and 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.