Debt - Narrative (Details)				1 Months Ended	2 Months Ended	12 Months Ended
	Apr. 10, 2020 USD ($)	Sep. 20, 2019 USD ($)	Aug. 08, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 03, 2020	Sep. 30, 2020 USD ($) invoice	Sep. 30, 2019 USD ($)	Dec. 17, 2018 USD ($)
Line of Credit Facility [Line Items]
Number of customer invoices | invoice						1
Notes Payable to Banks
Line of Credit Facility [Line Items]
Debt agreement term				6 months
Debt face amount				$ 1,137,000
Notes Payable to Banks
Line of Credit Facility [Line Items]
Weighted average interest rate						2.70%
Debt face amount						$ 1,465,000
Long-term loan repayment schedule period						72 months
Notes Payable to Banks | Minimum | Subsequent event
Line of Credit Facility [Line Items]
Debt agreement term					6 months
Notes Payable to Banks | Maximum | Subsequent event
Line of Credit Facility [Line Items]
Debt agreement term					12 months
Notes Payable to Banks | Euro Interbank Offered Rate (Euribor)
Line of Credit Facility [Line Items]
Basis spread on LIBOR						3.20%
Foreign subsidiary borrowings
Line of Credit Facility [Line Items]
Receivables pledged as collateral						$ 1,859,000	$ 672,000
Long-term debt						$ 5,759,000	$ 6,592,000
Foreign subsidiary borrowings | Euro Interbank Offered Rate (Euribor) | Minimum
Line of Credit Facility [Line Items]
Euribor variable interest rates						1.00%
Foreign subsidiary borrowings | Euro Interbank Offered Rate (Euribor) | Maximum
Line of Credit Facility [Line Items]
Euribor variable interest rates						4.20%
2018 Credit Agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Line of credit facility, covenant terms, fixed charge coverage ratio			1.1
Line of credit facility, availability of revolving commitment, fixed charge coverage ratio threshold			12.50%
Line of credit facility, stock pledged, non-U.S. subsidiaries, percentage		66.67%
2018 Credit Agreement | Revolving credit agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity			$ 30,000
Credit facility accordion feature, increase limit			$ 10,000
Weighted average interest rate						1.70%	3.60%
Commitment fee						0.25%
Debt issuance costs incurred						$ 212,000	$ 75,000
Revolving line of credit, accumulated amortization of debt issuance costs						$ 205,000	$ 106,000
2018 Credit Agreement | Revolving credit agreement | Revolving credit agreement | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on LIBOR						1.50%
Export Credit Facility | Revolving credit agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity								$ 5,000,000
Credit facility accordion feature, increase limit								$ 35,000,000
Weighted average interest rate						1.20%	3.40%
Export Credit Facility | Revolving credit agreement | Revolving credit agreement | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on LIBOR						1.00%	1.25%
Third Amendment To Credit Agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Line of credit facility, availability of revolving commitment, fixed charge coverage ratio threshold for three or more business days in any consecutive 30 day period		12.50%
Fourth Amendment To Credit Agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Line of credit facility, covenant terms, fixed charge coverage ratio						1.1
Line of credit facility, availability of revolving commitment, fixed charge coverage ratio threshold						12.50%
Line of credit facility, availability of revolving commitment, fixed charge coverage ratio threshold for three or more business days in any consecutive 30 day period		10.00%
Receivables pledged as collateral						$ 26,964,000	$ 24,000,000
Fourth Amendment To Credit Agreement | Revolving credit agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity						35,000	35,000
Line of credit facility floor		$ 2,000,000
Line of credit facility, amount available						13,284,000	$ 7,709,000
Paycheck Protection Program Loan | Unsecured Debt
Line of Credit Facility [Line Items]
Debt agreement term	2 years
Debt face amount	$ 5,025,000
Interest rate, fixed percentage	0.98%
Deferral term	6 months
Paycheck Protection Program Loan | Unsecured Debt | JPMORGAN CHASE BANK N.A.
Line of Credit Facility [Line Items]
Repayments of debt						261,000
Long-term debt						4,764,000
Long-term debt paid in 2021						3,176,000
Long-term debt paid in 2022						$ 1,588,000