Note 2 - Summary of Significant Accounting Policies (Details Textual)	12 Months Ended
	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022
Self Insurance Reserve, Noncurrent	$ 368,704,000	$ 326,920,000
Assets, Current	1,770,983,000	1,961,192,000
Deferred Income Tax Liabilities, Net	896,249,000	986,097,000
Accounts Receivable, Allowance for Credit Loss, Recovery	11,800,000	9,000,000
Accounts Receivable, Allowance for Credit Loss, Writeoff	4,000,000	6,700,000
Equity Securities, FV-NI, Current	$ 0	0
Number of Operating Segments	5
Derivative, Number of Instruments Held	0
Self Insurance, Per Claim Amount, Personal Injury and Property Damage Claims	$ 500,000
Claims Accruals, Current	232,000,000	196,000,000
Claims Accruals, Noncurrent	369,000,000	327,000,000
Prepaid Insurance, Current and Noncurrent	429,000,000	493,000,000
Other Receivables [Member]
Prepaid Insurance, Current and Noncurrent	116,000,000	102,000,000
Prepaid Expenses and Other Current Assets [Member]
Prepaid Insurance, Current and Noncurrent	121,000,000	217,000,000
Other Assets [Member]
Prepaid Insurance, Current and Noncurrent	$ 192,000,000	$ 174,000,000
Revenue Benchmark [Member] | Customer Concentration Risk [Member]
Number of Major Customers	1	1	1
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Top 10 Customers [Member]
Concentration Risk, Percentage	35.00%	36.00%	38.00%
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | One Customer [Member]
Concentration Risk, Percentage	11.00%	13.00%	14.00%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Top 10 Customers [Member]
Concentration Risk, Percentage	29.00%	34.00%
Minimum [Member]
Property, Plant and Equipment, Salvage Value, Percentage	10.00%
Finite-Lived Intangible Asset, Useful Life	2 years
Maximum [Member]
Property, Plant and Equipment, Useful Life	10 years
Property, Plant and Equipment, Salvage Value, Percentage	30.00%
Finite-Lived Intangible Asset, Useful Life	15 years
Tractors [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	4 years
Tractors [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	70 days
Trailing Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	7 years
Trailing Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	25 years
Land, Buildings and Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	10 years
Land, Buildings and Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	40 years
Computer Hardware and Software [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	10 years
Trade Accounts Receivable [Member]
Accounts Receivable, Allowance for Credit Loss	$ 32,400,000	$ 24,600,000
Revision of Prior Period, Reclassification, Adjustment [Member]
Self Insurance Reserve, Noncurrent		326,900,000
Assets, Current		(173,600,000)
Revision of Prior Period, Error Correction, Adjustment [Member]
Deferred Income Tax Liabilities, Net		$ 49,900,000