Railcar Leasing and Services Group - Lease Portfolio Sales (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Property Subject to or Available for Operating Lease [Line Items]
Lease portfolio sales			$ 186.7	$ 185.7
Operating profit on lease portfolio sales	$ 141.9	$ 99.1	257.1	168.1
Operating Segments [Member]
Property Subject to or Available for Operating Lease [Line Items]
Operating profit on lease portfolio sales	178.4	140.4	322.5	249.1
Operating Segments [Member] | Leasing & Services
Property Subject to or Available for Operating Lease [Line Items]
Operating profit on lease portfolio sales	$ 128.0	$ 116.1	$ 228.3	$ 200.7
Operating Profit Margin	45.50%	43.30%	40.30%	40.00%
Operating Segments [Member] | Sales of Leased Railcars [Domain] | Leasing & Services
Property Subject to or Available for Operating Lease [Line Items]
Lease portfolio sales	$ 162.5	$ 129.0	$ 186.7	$ 185.7
Operating Profit Margin	14.00%	23.10%	13.30%	23.30%
Operating Segments [Member] | Sales of Leased Railcars, Excluding Sales-Type Leases | Leasing & Services
Property Subject to or Available for Operating Lease [Line Items]
Operating profit on lease portfolio sales	$ 22.7	$ 29.8	$ 24.8	$ 43.3