Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Nov. 30, 2011	Nov. 30, 2010
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (10,267)	$ (13,821)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,203	1,357
Gain on sale of idle property, plant and equipment	(2,500)
Change in assets and liabilities:
Accrued interest receivable	5	(1)
Accounts receivable	3,533	3,648
Inventories	(1,314)	(166)
Other current assets	360	1,346
Accounts payable, trade	(728)	(1,183)
Accrued liabilities	1,963	1,239
Other, net	31	(17)
Net cash used in operating activities	(7,714)	(7,598)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from principal payments of U.S. Treasury Bills	34,985	129,966
Purchase of U.S. Treasury Bills	(30,991)	(116,967)
Proceeds from sale of idle property, plant and equipment	4,071
Purchase of property, plant and equipment	(466)	(306)
Other, net	(45)	(73)
Net cash provided by investing activities	7,554	12,620
CASH FLOWS FROM FINANCING ACTIVITIES:
Cash dividends paid	(1,511)	(3,021)
Net cash used in financing activities	(1,511)	(3,021)
Net (decrease) increase in cash	(1,671)	2,001
Cash at beginning of period	9,727	9,268
Cash at end of period	$ 8,056	$ 11,269