CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Income Statement [Abstract]
Contract manufacturing revenue	$ 13,781	$ 6,819	$ 36,548	$ 46,678
Cost of contract manufacturing	11,731	10,951	32,972	47,641
Gross profit (loss)	2,050	(4,132)	3,576	(963)
Operating expenses:
Selling, general and administrative	3,242	4,824	9,273	12,273
Restructuring charges	0	0	0	1,258
Total operating expenses	3,242	4,824	9,273	13,531
Operating loss	(1,192)	(8,956)	(5,697)	(14,494)
Interest and other income, net	9	28	190	65
Loss from continuing operations before income taxes	(1,183)	(8,928)	(5,507)	(14,429)
Income tax benefit	44	0	217	0
Loss from continuing operations	(1,139)	(8,928)	(5,290)	(14,429)
Income (loss) from discontinued operations, net of tax	0	(2,076)	739	(10,404)
Net loss	(1,139)	(11,004)	(4,551)	(24,833)
Comprehensive loss	(1,139)	(11,004)	(4,551)	(24,833)
Series E preferred stock accumulated dividends	(1,442)	(1,442)	(3,604)	(3,604)
Net loss attributable to common stockholders	$ (2,581)	$ (12,446)	$ (8,155)	$ (28,437)
Basic and diluted weighted average common shares outstanding	56,068,844	45,225,804	55,949,164	45,032,335
Basic and diluted net (loss) income per common share attributable to common stockholders: Continuing operations	$ (0.05)	$ (0.23)	$ (0.16)	$ (0.40)
Basic and diluted net (loss) income per common share attributable to common stockholders: Discontinued operations	0	(0.05)	0.01	(0.23)
Net loss per share attributable to common stockholders	$ (0.05)	$ (0.28)	$ (0.15)	$ (0.63)