Note 16 - Employee and Non-employee Stock Options - Summary of Stock Option Activity (Details) - USD ($)	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Outstanding, shares (in shares)	10,000	40,000
Outstanding, weighted average exercise price per share (in dollars per share)	$ 10.08	$ 8.74
Outstanding, weighted average remaining life (Year)	5 years 47 days	6 years 54 days	2 years 32 days
Outstanding, aggregate intrinsic value	$ 140,193	$ 101,000	$ 617,000
Granted, shares (in shares)	0	0
Granted, weighted average exercise price per share (in dollars per share)	$ 0	$ 0
Exercised, shares (in shares)	(818)	0
Exercised, weighted average exercise price per share (in dollars per share)	$ 10.56	$ 0
Forfeited, shares (in shares)		(30,000)
Forfeited, weighted average exercise price per share (in dollars per share)
Repurchased, shares (in shares)	0	0
Repurchased, weighted average exercise price per share (in dollars per share)	$ 0	$ 0
Outstanding, shares (in shares)	9,182	10,000	40,000
Outstanding, weighted average exercise price per share (in dollars per share)	$ 10.03	$ 10.08	$ 8.74
Exercisable, shares (in shares)	9,182
Exercisable, weighted average exercise price per share (in dollars per share)	$ 10.03
Exercisable, weighted average remaining life (Year)	5 years 47 days
Exercisable, aggregate intrinsic value	$ 140,193