Note 8 - Share-Based Compensation - Summary of Option Activity Under Stock Plans (Details) - USD ($)	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Outstanding (in shares)	1,433,216	1,469,306	1,495,856	1,251,166
Outstanding. (in dollars per share)	$ 4.08	$ 4.04	$ 4.03	$ 3.54
Outstanding	6 years 146 days	7 years 109 days	8 years 109 days	9 years
Outstanding	$ 6,221,909	$ 2,034,303	$ 1,174,810	$ 8,243,956
Granted (in shares)	45,000	6,000	258,000
Granted. (in dollars per share)	$ 4.72	$ 5.56	$ 6.30
Exercised (in shares)	(60,200)	(15,100)	(9,970)
Exercised. (in dollars per share)	$ 3.58	$ 2.43	$ 2.34
Forfeited (in shares)	(20,890)	(17,450)	(3,340)
Forfeited. (in dollars per share)	$ 4.28	$ 4.53	$ 3.21
Exercisable at March 31, 2015 (in shares)	818,800
Exercisable at March 31, 2015 (in dollars per share)	$ 3.73
Exercisable at March 31, 2015	6 years 36 days
Exercisable at March 31, 2015	$ 3,843,905