Income Taxes - Tax Effects of Temporary Differences and Carry-Forwards (Details) - USD ($)	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Deferred Tax Assets [Abstract]
Inventory reserve	$ 239,000		$ 301,000
Other reserves and accruals	358,000		207,000
Stock-based compensation	6,000		23,000
Tax credit carry-forwards	1,724,000		1,966,000
Federal tax loss carry-forwards	1,169,000		1,980,000
State tax loss carry-forwards	250,000		734,000
Foreign tax loss carry-forwards	67,000		127,000
Total deferred income taxes	3,813,000		5,338,000
Valuation allowance	(388,000)	$ (400,000)	(5,097,000)
Total deferred income tax liabilities	118,000		114,000
Net deferred tax assets	3,307,000		127,000
Deferred Tax Liabilities [Abstract]
Fixed assets	100,000		90,000
Other	18,000		24,000
Total deferred income tax liabilities	$ 118,000		$ 114,000