Note 9 - Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Federal/State	$ 123,527	$ 33,220	$ (11,117)
Foreign	19,883	18,494	15,028
Total	143,410	51,714	3,911
Federal/State	25,822	1,725	23,903
Foreign	18,171	(4,275)	2,803
Total	43,993	(2,550)	26,706
	$ 187,403	$ 49,164	$ 30,617