Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Capital Contributed in Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Total
Balance at Apr. 30, 2019	$ 835	$ 51,205	$ 49,052	$ (7,031)	$ (4,215)	$ 89,846
Balance (in shares) at Apr. 30, 2019	8,353
Issuance of restricted common stock	$ 1	56	0	0	0	57
Issuance of restricted common stock (in shares)	9
Net income (loss)	$ 0	0	(196)	0	0	(196)
Other comprehensive income	0	0	0	154	0	154
Balance at Jul. 31, 2019	$ 836	51,261	48,856	(6,877)	(4,215)	89,861
Balance (in shares) at Jul. 31, 2019	8,362
Balance at Apr. 30, 2020	$ 836	51,334	43,149	(6,467)	(4,215)	84,637
Balance (in shares) at Apr. 30, 2020	8,358
Issuance of restricted common stock	$ 1	41	0	0	0	42
Issuance of restricted common stock (in shares)	9
Net income (loss)	$ 0	0	593	0	0	593
Other comprehensive income	0	0	0	90	0	90
Balance at Jul. 31, 2020	$ 837	$ 51,375	$ 43,742	$ (6,377)	$ (4,215)	$ 85,362
Balance (in shares) at Jul. 31, 2020	8,367