Income Taxes - Deferred Tax Assets and Liabilities (Detail) (USD $)	Sep. 30, 2014	Sep. 30, 2013
Deferred Tax Assets:
Accrued liabilities and reserves	$ 288,000	$ 338,000
Allowance for doubtful accounts	91,000	115,000
Inventory	186,000	202,000
R&D tax credits carryforwards	671,000	805,000
Non-deductible stock compensation	194,000	178,000
Net operating losses carryforwards	58,000	59,000
Other	24,000	57,000
Gross Deferred Tax Assets	1,512,000	1,754,000
Deferred and Other Tax Liabilities:
Unrealized gain on investments	(798,000)	(736,000)
Percentage of completion	(104,000)
Property, plant and equipment	(964,000)	(1,179,000)
Unrecognized tax benefits	(300,000)	(300,000)
Other	(39,000)	(23,000)
Gross Deferred and Other Tax Liabilities	(2,205,000)	(2,238,000)
Net Deferred Income and Other Tax Liabilities	$ (693,000)	$ (484,000)