Note L - Stockholders' Equity, Stock Plans and Other Employee Benefit Plans - Transactions With Respect to Restricted Stock (Details) - Restricted Stock [Member]	12 Months Ended
	Mar. 31, 2019 $ / shares shares
Unvested restricted stock, Shares (in shares) | shares	5,000
Unvested restricted stock, weighted average grant date fair value per share (in dollars per share) | $ / shares	$ 49.80
Granted, Shares (in shares) | shares	1,000
Granted, weighted average grant date fair value per share (in dollars per share) | $ / shares	$ 89.90
Vested, Shares (in shares) | shares	(5,000)
Vested, weighted average grant date fair value per share (in dollars per share) | $ / shares	$ (49.80)
Unvested restricted stock, Shares (in shares) | shares	1,000
Unvested restricted stock, weighted average grant date fair value per share (in dollars per share) | $ / shares	$ 89.90