Business Segments (Details) $ in Millions	12 Months Ended
	Sep. 30, 2023 USD ($) segment	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Business segments
Number of business segments | segment	1
Flat Panel Display Systems
Geographic Data
Concentration risk threshold percentage	99.00%	98.00%	88.00%
Foreign Countries
Geographic Data
Net sales from outside the United States | $	$ 15.5	$ 11.1	$ 8.4