Note 7 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

	Years ended December 31,
	2019		2018		2017
Current:
Federal	$	87,977	$	22,904	$	134,284
State and local		20,981		26,738		23,456
		108,958		49,642		157,740
Deferred:
Federal		51,229		97,670		(261,592	)
State and local		4,388		3,921		12,828
		55,617		101,591		(248,764	)
Total tax expense/(benefit)	$	164,575	$	151,233	$	(91,024	)

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Years ended December 31,
	2019			2018			2017
Income tax at federal statutory rate	$	142,988		$	134,572		$	208,334
State tax, net of federal effect		19,293			24,627			18,334
Federal tax reform		-			(3,219	)		(309,223	)
Benefit of stock compensation		(1,238	)		(4,919	)		(4,907	)
199/R&D credit		(200	)		1,000			(7,056	)
Nondeductible meals and entertainment		1,688			1,071			1,374
Change in effective state tax rate, net of federal benefit		1,562			(1,469	)		3,403
Other, net		482			(430	)		(1,283	)
Total tax expense	$	164,575		$	151,233		$	(91,024	)

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	December 31,
	2019			2018
Deferred tax assets:
Insurance accruals	$	27,180		$	34,889
Allowance for doubtful accounts		8,052			7,649
Compensation accrual		4,925			10,461
Deferred compensation accrual		24,521			20,396
Federal benefit of state uncertain tax positions		9,867			10,364
Lease liabilities		30,251			-
State NOL carry-forward		7,495			6,041
Other		6,357			4,626
Total gross deferred tax assets		118,648			94,426
Valuation allowance		(7,495	)		(6,041	)
Total deferred tax assets, net of valuation allowance		111,153			88,385
Deferred tax liabilities:
Plant and equipment, principally due to differences in depreciation		729,016			696,913
Prepaid permits and insurance, principally due to expensing for income tax purposes		39,285			33,594
Lease right-of-use assets		30,014			-
Other		11,916			1,339
Total gross deferred tax liabilities		810,231			731,846
Net deferred tax liability	$	699,078		$	643,461

Summary of Positions for which Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Table Text Block]

	December 31,
	2019			2018			2017
Beginning balance	$	52.2		$	45.3		$	35.4
Additions based on tax positions related to the current year		11.0			13.9			11.6
Additions/(reductions) based on tax positions taken in prior years		(6.5	)		(2.4	)		5.4
Reductions due to settlements		-			-			(2.4	)
Reductions due to lapse of applicable statute of limitations		(6.1	)		(4.6	)		(4.7	)
Ending balance	$	50.6		$	52.2		$	45.3