Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jan. 31, 2020	Apr. 30, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in usd per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common stock, no par value (in usd per share)
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	16,925,247	16,849,026
Common stock, shares outstanding	16,925,247	16,849,026