Note 7 - Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income tax at federal statutory rate	$ 134,572	$ 208,334	$ 243,529
State tax, net of federal effect	24,627	18,334	19,165
Federal tax reform	(3,219)	(309,223)
Benefit of stock compensation	(4,919)	(4,907)
199/R&D credit	1,000	(7,056)
Nondeductible meals and entertainment	1,071	1,374	1,419
Change in effective state tax rate, net of federal benefit	(1,469)	3,403	(1,055)
Other, net	(430)	(1,283)	649
Total tax expense/(benefit)	$ 151,233	$ (91,024)	$ 263,707

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

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