Income Taxes Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Income Tax Disclosure [Line Items]
Effective Income Tax Rate Reconciliation, Percent	23.00%	27.70%	20.40%	25.10%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%
Deferred income taxes	$ 1,088.2		$ 1,088.2		$ 1,075.6
Inflation Reduction Act - Purchase of Federal Tax Credits			40.0
Inflation Reduction Act - Payment to Acquire Federal Tax Credits			38.4
Effective Income Tax Rate Reconciliation, Tax Credit, Amount			1.6
Railcars on Lease [Member]
Income Tax Disclosure [Line Items]
Deferred income taxes	$ 1,200.0		$ 1,200.0		$ 1,100.0