Note 7 - Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 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	0	(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/(benefit)	$ 164,575	$ 151,233	$ (91,024)

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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