CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital Contributions [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]
Balance at Apr. 30, 2015	$ 93,321	$ 828	$ 50,538	$ 57,003	$ (10,833)	$ (4,215)
Balance (in shares) at Apr. 30, 2015		8,282
Issuance of restricted common stock	15	$ 0	15	0	0	0
Issuance of restricted common stock (in shares)		3
Net loss	(10,224)	$ 0	0	(10,224)	0	0
Other comprehensive income (loss)	(268)	0	0	0	(268)	0
Balance at Apr. 30, 2016	82,844	$ 828	50,553	46,779	(11,101)	(4,215)
Balance (in shares) at Apr. 30, 2016		8,285
Issuance of restricted common stock	92	$ 2	90	0	0	0
Issuance of restricted common stock (in shares)		18
Issuance of deferred common stock units	51	$ 0	51	0	0	0
Issuance of deferred common stock units (in shares)		0
Net loss	(15)	$ 0	0	(15)	0	0
Other comprehensive income (loss)	1,861	0	0	0	1,861	0
Balance at Apr. 30, 2017	$ 84,833	$ 830	$ 50,694	$ 46,764	$ (9,240)	$ (4,215)
Balance (in shares) at Apr. 30, 2017		8,303