Purchase Commitments (Details) $ in Millions	Mar. 31, 2024 USD ($)
Capital Addition Purchase Commitments Total Revenue Equipment [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Future Minimum Payments, Remainder of Fiscal Year	$ 505.3
Purchase Obligation, to be Paid, Year One	505.3
Purchase Obligation, to be Paid, Year Two	0.0
Purchase Obligation, to be Paid, Year Three	0.0
Purchase Obligation, Due in Fourth and Fifth Year	0.0
Purchase Obligation, Due after Fifth Year	0.0
Capital Addition Purchase Commitments of Tractors [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Future Minimum Payments, Remainder of Fiscal Year	440.1
Capital Addition Purchase Commitments Non revenue equipment [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation, Future Minimum Payments, Remainder of Fiscal Year	102.1
Purchase Obligation, to be Paid, Year One	102.1
Purchase Obligation, Due in Second and Third Year	12.3
Purchase Obligation, Due in Fourth and Fifth Year	0.2
Purchase Obligation, Due after Fifth Year	$ 0.0