Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	3 Months Ended
	Aug. 31, 2011	Aug. 31, 2010
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (6,845)	$ (6,065)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	615	685
Changes in assets and liabilities:
Accrued interest receivable	7	(1)
Accounts receivable	884	802
Inventories	(1,554)	(77)
Other current assets	183	68
Accounts payable, trade	(74)	95
Accrued liabilities	1,640	993
Other, net	(2)	8
Net cash used in operating activities	(5,146)	(3,492)
CASH FROM INVESTING ACTIVITIES:
Proceeds from principal payments of U.S. Treasury Bills	26,986	66,983
Purchase of U.S. Treasury Bills	(22,994)	(62,981)
Purchase of property, plant and equipment	(353)	(131)
Other, net	(48)	(52)
Net cash provided by investing activities	3,591	3,819
CASH FLOWS FROM FINANCING ACTIVITIES:
Cash dividends paid	(755)	(1,510)
Net cash used in financing activities	(755)	(1,510)
Net decrease in cash	(2,310)	(1,183)
Cash at beginning of period	9,727	9,268
Cash at end of period	$ 7,417	$ 8,085