Accident and Workers' Compensation Insurance Liabilities	12 Months Ended
	Dec. 31, 2024
Accident and Workers' Compensation Insurance Liabilities [Abstract]
Accident and Workers' Compensation Insurance Liabilities	Auto Liability and Workers’ Compensation Insurance Accruals We act as a self-insurer for auto liability, defined as including property damage, personal injury, or cargo based on defined insurance retention. In April 2023, we renewed our primary auto liability insurance with a three year program. Under the April 2023 renewal, our auto liability retention limit across all operating entities was increased to $3.0 million for any individual claim based on the insured party, accident date, and circumstances of the loss event subject to a $3.5 million corridor for any one accident or combination of accidents that exceed $3.0 million. Prior to the April 2023 renewal, Heartland Express, Millis Transfer, and CFI had a retention limit of $2.0 million and Smith Transport had a retention limit of $0.5 million. In addition to the $2.0 million base retention limit, Heartland Express, Millis Transfer, and CFI were subject to a $1.0 million corridor for any one accident or combination of accidents that exceeded $2.0 million. For the April 2023 renewal, liabilities in excess of the $3.0 million deductible and $3.5 million corridor are covered by insurance up to $80.0 million. In April 2024, an additional corridor was added, where we retain liability of $5.0 million for any one accident or combination of accidents that exceed $10.0 million. Liabilities in excess of the $3.0 million deductible, the $3.5 million corridor, and the $5.0 million corridor are covered by insurance up to $80.0 million. We retain any liability in excess of $80.0 million. Prior to the April 2023 renewal, our excess limit was $60.0 million, including retention of 50% of exposure from $5.0 million to $10.0 million. Furthermore, under the April 2023 renewal, our premiums are subject to upward or downward adjustments based on claims experience in the $3.0 million to $10.0 million policy during the three year program. The elevated retention limit and the premium adjustment feature could lead to increased volatility in our insurance and claims expense, depending on the frequency and magnitude of claims. We act as a self-insurer for property damage to our tractors and trailers. We act as a self-insurer for workers’ compensation based on defined insurance retention of $1.0 million. Liabilities in excess of insurance retention limits are covered by insurance. The State of Iowa initially required us to deposit $0.7 million into a trust fund as part of the self-insurance program. As of December 31, 2024 and 2023 total deposits in this account were $0.9 million and $0.9 million, respectively. This deposit is made up of fixed income investments classified as held-to-maturity. The deposit is recorded in other non-current assets on the consolidated balance sheets. In addition, we have provided insurance carriers with letters of credit totaling $13.2 million in connection with our liability and workers’ compensation insurance arrangements and self-insurance requirements of the Federal Motor Carrier Safety Administration. There were no outstanding balances due on any letters of credit at December 31, 2024 or 2023. Accident and workers’ compensation accruals include the estimated settlements, settlement expenses and an estimate for claims incurred but not yet reported for property damage, personal injury and public liability losses from vehicle accidents and cargo losses as well as workers’ compensation claims for amounts not covered by insurance. Accident and workers’ compensation accruals are based upon individual case estimates, including reserve development, and estimates of incurred-but-not-reported losses based upon our own historical experience and industry claim trends. Since the reported liability is an estimate, the ultimate liability may be more or less than reported. In addition to internally developed reserves and estimates, we utilize an actuarial specialist to provide an independent annual assessment of the internally developed accident and workers' compensation accruals. If adjustments to previously established accruals are required, such amounts are included in operating expenses in the current period. These accruals are recorded on an undiscounted basis. Estimated claim payments to be made within one year of the balance sheet date have been classified as insurance accruals within current liabilities as of December 31, 2024 and 2023.