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Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) | 12 Months Ended
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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% |

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