Railcar Leasing and Services Group - Lease Portfolio Sales (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Property Subject to or Available for Operating Lease [Line Items]
Lease portfolio sales	$ 24.2	$ 56.7
Operating profit on lease portfolio sales	115.2	69.0
Operating Segments [Member]
Property Subject to or Available for Operating Lease [Line Items]
Operating profit on lease portfolio sales	144.1	108.7
Operating Segments [Member] | Leasing & Services
Property Subject to or Available for Operating Lease [Line Items]
Operating profit on lease portfolio sales	$ 100.3	$ 84.6
Operating Profit Margin	35.20%	36.30%
Operating Segments [Member] | Sales of Leased Railcars [Domain] | Leasing & Services
Property Subject to or Available for Operating Lease [Line Items]
Lease portfolio sales	$ 24.2	$ 56.7
Operating Profit Margin	8.70%	23.80%
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	$ 2.1	$ 13.5