Note 6 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

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

	Years ended December 31,
	2012		2011		2010
Current:
Federal	$	152,140	$	32,845	$	70,381
State and local		21,095		8,171		9,595
		173,235		41,016		79,976
Deferred:
Federal		12,458		110,495		37,897
State and local		8,594		7,216		2,204
		21,052		117,711		40,101
Total tax expense	$	194,287	$	158,727	$	120,077

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

	Years ended December 31,
	2012		2011		2010
Income tax at federal statutory rate	$	176,624	$	145,506	$	111,893
State tax, net of federal effect		16,191		9,668		6,337
Nondeductible meals and entertainment		1,568		1,570		1,627
Change in effective state tax rate, net of federal benefit		126		1,611		141
Valuation allowance		--		552		--
Other, net		(222)		(180)		79
Total tax expense	$	194,287	$	158,727	$	120,077

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

	December 31,
	2012			2011
Deferred tax assets:
Insurance accruals	$	9,713		$	8,316
Allowance for doubtful accounts		1,715			1,827
Compensation accrual		16,851			20,522
Deferred compensation accrual		25,997			24,727
Federal benefit of state uncertain tax positions		10,586			7,155
Equity investment		2,197			2,197
Other		3,403			3,584
Total gross deferred tax assets		70,462			68,328
Valuation allowance		(2,749	)		(2,749	)
Total deferred tax assets, net of valuation allowance		67,713			65,579
Deferred tax liabilities:
Plant and equipment, principally due to differences in depreciation		571,830			551,526
Prepaid permits and insurance, principally due to expensing for income tax purposes		19,069			17,605
Other		9,188			8,027
Total gross deferred tax liabilities		600,087			577,158
Net deferred tax liability	$	532,374		$	511,579

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

	December 31,
	2012			2011			2010
Beginning balance	$	17.4		$	17.3		$	18.9
Additions based on tax positions related to the current year		7.1			4.0			4.2
Additions/(reductions) based on tax positions taken in prior years		4.2			(0.3	)		(1.4	)
Reductions due to settlements		--			(0.4	)		(1.8	)
Reductions due to lapse of applicable statute of limitations		(2.9	)		(3.2	)		(2.6	)
Ending balance	$	25.8		$	17.4		$	17.3