Note 6 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Insurance accruals	$ 83,380	$ 69,168
Allowance for doubtful accounts	12,149	12,584
Compensation accrual	15,881	9,882
Deferred compensation accrual	24,484	26,805
Federal benefit of state uncertain tax positions	16,377	17,693
Lease liabilities	60,849	74,858
State NOL carry-forward	2,602	4,235
Other	1,112	3,815
Total gross deferred tax assets	216,834	219,040
Valuation allowance	(2,602)	(4,235)
Total deferred tax assets, net of valuation allowance	214,232	214,805
Plant and equipment, principally due to differences in depreciation	1,031,019	1,001,537
Prepaid permits and insurance, principally due to expensing for income tax purposes	31,721	35,592
Lease right-of-use assets	59,797	73,925
Total gross deferred tax liabilities	1,122,537	1,111,054
Net deferred tax liability	$ 908,305	$ 896,249