Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Feb. 28, 2014	Feb. 28, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (9,304)	$ (10,558)
Adjustments to reconcile net loss to net cash from operating activities:
Depreciation	1,304	1,523
Gain on sale of idle property, plant and equipment	(462)	(1,411)
Change in assets and liabilities:
Restricted cash	600	(600)
Accrued interest receivable	1	4
Accounts receivable	(1,723)	(2,515)
Inventories	(2,502)	(1,981)
Other current assets	(32)	(280)
Accounts payable, trade	118	264
Accrued liabilities	3,400	1,859
Other, net	(527)	(71)
Net cash from operating activities	(9,127)	(13,766)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from principal payments of U.S. Treasury Bills	30,998	48,987
Purchase of U.S. Treasury Bills	(28,999)	(37,993)
Proceeds from note receivable	35	11
Proceeds from sale of idle property, plant and equipment	958	348
Purchase of property, plant and equipment	(649)	(49)
Other, net	221	109
Net cash from investing activities	2,564	11,413
Net decrease in cash	(6,563)	(2,353)
Cash at beginning of period	11,838	12,011
Cash at end of period	5,275	9,658
NON-CASH TRANSACTIONS:
Note receivable from sale of idle property, plant and equipment	$ 0	$ 1,689