Note 11 - Stock Based Compensation - Stock Option Activity (Details) - $ / shares					9 Months Ended	12 Months Ended
	Apr. 01, 2018	Feb. 03, 2017	Nov. 01, 2016	Feb. 03, 2014	Dec. 31, 2018	Mar. 31, 2018	Mar. 31, 2017
Outstanding, beginning of period (in shares)	242,350				242,350	242,350
Outstanding, beginning of period (in dollars per share)					$ 13.87	$ 13.84	$ 13.84
Outstanding, beginning of period (Year)					5 years 219 days	6 years 36 days	7 years 36 days
Granted (in shares)	20,354	3,700	19,000	225,150	20,354
Granted (in dollars per share)					$ 14.25
Granted (Year)					9 years 109 days
Exercised (in shares)
Exercised (in dollars per share)
Exercised (Year)
Forfeited, exchanged or expired (in shares)
Forfeited, exchanged or expired (in dollars per share)
Forfeited, exchanged or expired (Year)
Outstanding, end of period (in shares)					262,704	242,350	242,350
Vested at end of year (in shares)					184,060	180,260
Vested at end of year (in dollars per share)					$ 13.84	$ 13.84
Vested at end of year (Year)					5 years 73 days	5 years 292 days