Consolidated Statements of Shareholders' Equity - USD ($) $ 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	8,353,000
Issuance of restricted common stock	$ 1	56				57
Issuance of restricted common stock (in shares)	9,000
Net income (loss)			(2,365)			(2,365)
Other comprehensive income				2,301		2,301
Balance at Oct. 31, 2019	$ 836	51,261	46,687	(4,730)	(4,215)	89,839
Balance (in shares) at Oct. 31, 2019	8,362,000
Balance at Jul. 31, 2019	$ 836	51,261	48,856	(6,877)	(4,215)	89,861
Balance (in shares) at Jul. 31, 2019	8,362,000
Net income (loss)	$ 0	0	(2,169)	0	0	(2,169)
Other comprehensive income	0	0	0	2,147	0	2,147
Balance at Oct. 31, 2019	$ 836	51,261	46,687	(4,730)	(4,215)	89,839
Balance (in shares) at Oct. 31, 2019	8,362,000
Balance at Apr. 30, 2020	$ 836	51,334	43,149	(6,467)	(4,215)	84,637
Balance (in shares) at Apr. 30, 2020	8,358,000
Issuance of restricted common stock	$ 1	41				42
Issuance of restricted common stock (in shares)	9,000
Issuance of common stock settled from deferred common share units (in shares)	12,000
Repurchase of common stock	$ (69)	(4,159)				(4,228)
Repurchase of common stock (in shares)	(687,000)
Net income (loss)			1,391			1,391
Other comprehensive income				180		180
Balance at Oct. 31, 2020	$ 768	47,216	44,540	(6,287)	(4,215)	82,022
Balance (in shares) at Oct. 31, 2020	7,692,000
Balance at Jul. 31, 2020	$ 837	51,375	43,742	(6,377)	(4,215)	$ 85,362
Balance (in shares) at Jul. 31, 2020	8,367,000
Issuance of common stock settled from deferred common share units	$ 0	0	0	0	0
Issuance of common stock settled from deferred common share units (in shares)	12,000					12,411
Repurchase of common stock	$ (69)	(4,159)	0	0	0	$ (4,228)
Repurchase of common stock (in shares)	(687,000)
Net income (loss)	$ 0	0	798	0	0	798
Other comprehensive income	0	0	0	90	0	90
Balance at Oct. 31, 2020	$ 768	$ 47,216	$ 44,540	$ (6,287)	$ (4,215)	$ 82,022
Balance (in shares) at Oct. 31, 2020	7,692,000