Summary of Significant Accounting Policies Lessor Accounting (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term		5 years		5 years
Lessor, Operating Lease, Option to Terminate				one year
Sales-type lease revenues		$ 0.0		$ 0.0
Direct Financing Lease, Revenue		0.0		0.0
Operating lease revenues		158.2	$ 169.1	486.2	$ 506.4
Variable operating lease revenues		18.8	$ 9.0	44.7	$ 32.2
Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Remaining three months of 2021	[1]	146.7		146.7
2022	[1]	497.6		497.6
2023	[1]	374.8		374.8
2024	[1]	280.2		280.2
2025	[1]	198.0		198.0
Thereafter	[1]	344.4		344.4
Total	[1]	$ 1,841.7		$ 1,841.7
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] 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.