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%