Note 2 - Restatement of Previously Issued Financial Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2021
Cost of products sold	$ 1,405,033	$ 1,243,684	$ 1,235,459
Total costs and expenses	1,487,993	1,321,271	1,286,577
Operating income	21,359	64,009	181,067
Earnings before income taxes	13,793	59,895	160,016
Income taxes	4,562	13,695	33,916
Net earnings	$ 9,231	$ 46,200	$ 126,100
Basic (in dollars per share)	$ 1.19	$ 5.28	$ 13.82
Diluted (in dollars per share)	$ 1.16	$ 5.24	$ 13.72
Inventories	$ 670,898	$ 403,995
Refundable income taxes	6,976	5,446
Total current assets	794,039	550,686
Total assets	1,212,721	942,274
Income taxes payable	0	0
Total current liabilities	156,188	173,155
Deferred income tax liability, net	31,481	33,016
Other liabilities	3,639	4,974
Total liabilities	657,971	363,244
Retained earnings	641,259	632,051
Total stockholders’ equity	554,750	579,030
Total liabilities and stockholders’ equity	1,212,721	942,274
Previously Reported [Member]
Cost of products sold	1,373,456	1,237,348
Total costs and expenses	1,456,416	1,314,935
Operating income	52,936	70,345
Earnings before income taxes	45,370	66,231
Income taxes	12,232	15,224
Net earnings	$ 33,138	$ 51,007
Basic (in dollars per share)	$ 4.23	$ 5.83
Diluted (in dollars per share)	$ 4.20	$ 5.79
Inventories	$ 708,811	$ 410,331
Refundable income taxes	0	3,866
Total current assets	824,976	555,442
Total assets	1,243,658	947,030
Income taxes payable	2,018	0
Total current liabilities	158,206	173,155
Deferred income tax liability, net	31,625	32,944
Other liabilities	3,700	4,995
Total liabilities	660,194	363,193
Retained earnings	669,973	636,858
Total stockholders’ equity	583,464	583,837
Total liabilities and stockholders’ equity	1,243,658	947,030
Revision of Prior Period, Adjustment [Member]
Cost of products sold	31,577	6,336
Total costs and expenses	31,577	6,336
Operating income	(31,577)	(6,336)
Earnings before income taxes	(31,577)	(6,336)
Income taxes	(7,670)	(1,529)
Net earnings	$ (23,907)	$ (4,807)
Basic (in dollars per share)	$ (3.04)	$ (0.55)
Diluted (in dollars per share)	$ (3.04)	$ (0.55)
Inventories	$ (37,913)	$ (6,336)
Refundable income taxes	6,976	1,580
Total current assets	(30,937)	(4,756)
Total assets	(30,937)	(4,756)
Income taxes payable	(2,018)	0
Total current liabilities	(2,018)	0
Deferred income tax liability, net	(144)	72
Other liabilities	(61)	(21)
Total liabilities	(2,223)	51
Retained earnings	(28,714)	(4,807)
Total stockholders’ equity	(28,714)	(4,807)
Total liabilities and stockholders’ equity	$ (30,937)	$ (4,756)