Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019
Statement Of Financial Position [Abstract]
Allowances on trade accounts receivable	$ 26	$ 33
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	500,000	500,000
Common stock, par value	$ 0.10	$ 0.10
Common stock, shares authorized	25,500,000	25,500,000
Common stock, shares issued	10,699,000	10,650,000
Common stock, shares outstanding	9,883,000	9,843,000
Treasury stock, shares	816,000	807,000