Income Taxes Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Income Tax Disclosure [Line Items]
Effective Income Tax Rate Reconciliation, Percent	22.70%	23.90%	23.80%	(11.30%)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%
Residual Tax Release from AOCI				$ 11.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities		$ 3.2		3.2
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount				$ 4.0
Income tax receivable	$ 4.6		$ 4.6		$ 5.2
Taxes Payable	7.6		7.6
Deferred income taxes	1,104.2		1,104.2		1,103.5
Railcars on Lease [Member]
Income Tax Disclosure [Line Items]
Deferred income taxes	$ 1,100.0		$ 1,100.0		$ 1,100.0