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Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) | 12 Months Ended
--- | ---
Sep. 30, 2020 | Sep. 30, 2019
Significant Accounting Policies [Line Items] |  |
Cash and cash equivalents held by foreign subsidiaries and branch offices | $ 5,800,000 |
Transition tax on undistributed earnings of foreign subsidiaries | 0 |
Accumulated foreign earnings | $ 0 |
Minimum credit limit | 30 days |
Extended credit terms for trade receivables | 60 days |
Goodwill impairment | $ 671,000 |
Goodwill | 4,337,000 | $ 5,008,000
Income tax, Interest or penalties incurred | $ 0 | 0
Accounting Standards Update 2016-02 |  |
Significant Accounting Policies [Line Items] |  |
Change in accounting principle, accounting standards update, adopted [true false] | true |
Change in Accounting Principle, Accounting Standards Update, Adoption Date | Oct. 01, 2019 |
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false] | false |
Accounting Standards Update 2018-07 |  |
Significant Accounting Policies [Line Items] |  |
Change in accounting principle, accounting standards update, adopted [true false] | true |
Change in Accounting Principle, Accounting Standards Update, Adoption Date | Oct. 01, 2019 |
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false] | true |
Accounting Standards Update 2018-13 |  |
Significant Accounting Policies [Line Items] |  |
Change in accounting principle, accounting standards update, adopted [true false] | true |
Change in Accounting Principle, Accounting Standards Update, Adoption Date | Oct. 01, 2019 |
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false] | true |
Accounting Standards Update 2017-04 |  |
Significant Accounting Policies [Line Items] |  |
Change in accounting principle, accounting standards update, adopted [true false] | true |
Change in Accounting Principle, Accounting Standards Update, Adoption Date | Jul. 01, 2020 |
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false] | true |
Change in accounting principle, accounting standards update, early adoption [true false] | true |
Oil and Gas Markets |  |
Significant Accounting Policies [Line Items] |  |
Goodwill impairment | $ 700,000 |
Emerging Markets |  |
Significant Accounting Policies [Line Items] |  |
Goodwill impairment | 0 |
Adjacent Markets |  |
Significant Accounting Policies [Line Items] |  |
Goodwill | $ 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 | 2.00% |
Product Concentration Risk | Sales Revenue, Net | Thermal Film |  |
Significant Accounting Policies [Line Items] |  |
Percentage of company revenue | 8.00% |
Customer one |  |
Significant Accounting Policies [Line Items] |  |
Trade account and financing receivable due | $ 7,300,000 | $ 12,100,000
Customer one | Customer Concentration Risk | Sales Revenue, Net |  |
Significant Accounting Policies [Line Items] |  |
Percentage of company revenue | 48.20% | 25.20%
Customer two |  |
Significant Accounting Policies [Line Items] |  |
Trade account and financing receivable due |  | $ 6,700,000
Customer two | Customer Concentration Risk | Sales Revenue, Net |  |
Significant Accounting Policies [Line Items] |  |
Percentage of company revenue |  | 19.70%

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