Note M - Share-based Compensation - Outstanding Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
		Jun. 30, 2019	Mar. 31, 2019
Options outstanding (in shares)	[1]	42,234
Options outstanding, weighted average exercise price (in dollars per share)	[1]	$ 46.807
Options outstanding, weighted average remaining contractual life (Year)		4 years 73 days	1 year 116 days	[1]
Options outstanding, aggregate intrinsic value	[1]		$ 1,127
Options granted (in shares)		0	10,000
Granted, weighted average exercise price (in dollars per share)			$ 89.90
Options exercised (in shares)		(32,234)
Exercised, weighted average exercise price (in dollars per share)		$ 33.438
Exercised, aggregate intrinsic value		$ 1,134
Options outstanding (in shares)		10,000	42,234	[1]
Options outstanding, weighted average exercise price (in dollars per share)		$ 89.90	$ 46.807	[1]
Options exercisable (in shares)
Options exercisable, weighted average exercise price (in dollars per share)

[1] Represents outstanding options after giving effect to the replacement options issued in connection with the Company’s special dividend to shareholders of record on December 22, 2017.