Note 6 - Income Taxes (Detail) - Reconciliation of Income Tax Expense (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 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

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period.

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