Summary of Significant Accounting Policies Lessor Accounting (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2018
Lessor, Lease, Description [Line Items]
Lessor, Operating Lease, Renewal Term		5 years		5 years
Lessor, Operating Lease, Termination Option Term				one year
Direct Financing Lease, Revenue		$ 0.0		$ 0.0
Operating lease revenues		169.1	$ 169.5	506.4	$ 506.9
Variable operating lease revenues		9.0	12.5	32.2	36.6
Sales-type lease revenues		0.0	26.3	0.0	60.5
Interest income on sales-type lease receivables		0.0	0.6	0.0	0.9
Profit recognized at sales-type lease commencement		0.0	$ 3.7	0.0	$ 7.8
Railcar Leasing and Management Services Group [Member]
Lessor, Lease, Description [Line Items]
Remaining three months of 2020	[1]	152.0		152.0
2021	[1]	516.5		516.5
2022	[1]	406.5		406.5
2023	[1]	296.9		296.9
2024	[1]	215.2		215.2
Thereafter	[1]	391.6		391.6
Total	[1]	$ 1,978.7		$ 1,978.7
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		20 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.