Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Significant Accounting Policies [Line Items]
Cash and cash equivalents held by foreign subsidiaries and branch offices	$ 5,200,000
Minimum credit limit	30 days
Extended credit terms for trade receivables	60 days
Income tax, Interest or penalties incurred	$ 0	$ 0
Product Concentration Risk | Sales Revenue, Net | Certain Models of Oil and Gas Marine Wireless Products
Significant Accounting Policies [Line Items]
Percentage of company revenue	0.00%
Product Concentration Risk | Sales Revenue, Net | Thermal Film
Significant Accounting Policies [Line Items]
Percentage of company revenue	7.00%
Customer one
Significant Accounting Policies [Line Items]
Trade account and financing receivable due	$ 4,900,000
Customer one | Customer Concentration Risk | Sales Revenue, Net
Significant Accounting Policies [Line Items]
Percentage of company revenue	19.80%
Customer two
Significant Accounting Policies [Line Items]
Trade account and financing receivable due	$ 7,400,000
Long-term trade account and financing receivable due	$ 2,100,000
Customer two | Customer Concentration Risk | Sales Revenue, Net
Significant Accounting Policies [Line Items]
Percentage of company revenue	16.40%
Major Customer
Significant Accounting Policies [Line Items]
Trade account and financing receivable due		$ 7,300,000
Major Customer | Customer Concentration Risk | Sales Revenue, Net
Significant Accounting Policies [Line Items]
Percentage of company revenue		48.20%
Customer three
Significant Accounting Policies [Line Items]
Trade account and financing receivable due	$ 1,100,000
Customer three | Customer Concentration Risk | Sales Revenue, Net
Significant Accounting Policies [Line Items]
Percentage of company revenue	10.60%