Debt - Narrative (Details)							1 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 20, 2019 USD ($)	Mar. 29, 2019	Dec. 17, 2018 USD ($)	Nov. 05, 2018	Aug. 08, 2018 USD ($)	Sep. 30, 2019 USD ($) repayment tranche	Dec. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) invoice	Sep. 30, 2018 USD ($)
Line of Credit Facility [Line Items]
Gain (loss) on extinguishment of debt									$ 0	$ (496,000)
Revolver	$ 15,542,000						$ 15,542,000		$ 15,542,000	21,253,000
Number of customer invoices | invoice									1
Foreign subsidiary borrowings
Line of Credit Facility [Line Items]
Receivables pledged as collateral	$ 672,000						$ 672,000		$ 672,000	2,007,000
Number of tranches with modified repayment schedule | tranche							1
Number of long-term debt repayments reduced | repayment							2
Repayments of debt reduction							$ 96,000
Debt loan extension period							6 months
Foreign subsidiary borrowings | Euro Interbank Offered Rate (Euribor) | Minimum
Line of Credit Facility [Line Items]
Euribor variable interest rates	1.00%						1.00%		1.00%
Foreign subsidiary borrowings | Euro Interbank Offered Rate (Euribor) | Maximum
Line of Credit Facility [Line Items]
Euribor variable interest rates	4.00%						4.00%		4.00%
2018 Credit Agreement | Line of Credit
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 | Line of Credit
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity						$ 30,000
Credit facility accordion feature, increase amount						$ 10,000
Line of credit facility, amount available	$ 7,709,000						$ 7,709,000		$ 7,709,000	$ 8,437,000
Weighted average interest rate	3.60%						3.60%		3.60%	3.85%
Commitment fee						0.25%
Debt issuance costs, gross	$ 75,000					$ 212,000	$ 75,000		$ 75,000
Accumulated amortization of debt issuance costs, revolver	$ 106,000						$ 106,000		$ 106,000	$ 12,000
2018 Credit Agreement | Revolving credit agreement | Line of Credit | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on LIBOR						1.50%
First Amendment To Credit Agreement And Security Agreement | Line of Credit
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%
Export Credit Facility | Revolving credit agreement | Line of Credit
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity				$ 5,000,000
Credit facility accordion feature, increase amount				$ 35,000,000
Weighted average interest rate	3.40%						3.40%		3.40%
Export Credit Facility | Revolving credit agreement | Line of Credit | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on LIBOR				1.25%
Third Amendment To Credit Agreement | Line of Credit
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 | Line of Credit
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		10.00%
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%	10.00%
Line of credit facility benchmark of collateral threshold		$ 20,000,000
Receivables pledged as collateral		24,000,000
Collateral spring line of credit facility availability	$ 2,400,000						$ 2,400,000		$ 2,400,000
Fourth Amendment To Credit Agreement | Revolving credit agreement | Line of Credit
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity	35,000,000						35,000,000		35,000,000
Line of credit facility, amount available	7,709,000						7,709,000		7,709,000
Line of credit facility floor		2,000,000
Line of credit facility benchmark of collateral threshold		$ 20,000,000
Total commitment spring line of credit facility availability	$ 3,500,000						$ 3,500,000		$ 3,500,000
Short Term Debt Arrangement For Working Capital Purposes
Line of Credit Facility [Line Items]
Debt agreement term								6 months
Revolver								$ 1,137,000
As Of August 31, 2018 Or September 30, 2018 | First Amendment To Credit Agreement And Security Agreement | Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility, covenant terms, fixed charge coverage ratio					1.1
On Or After October 31, 2018 | First Amendment To Credit Agreement And Security Agreement | Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility, covenant terms, fixed charge coverage ratio					1.1