Debt - Narrative (Details)							1 Months Ended		3 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 ($) tranche repayment	Dec. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) invoice
Line of Credit Facility [Line Items]
Short-term debt arrangement	$ 15,542,000						$ 15,542,000		$ 16,630,000
Number of customer invoices factored | invoice									1
Foreign subsidiary borrowings
Line of Credit Facility [Line Items]
Receivables pledged as collateral	$ 672,000						$ 672,000		$ 629,000
Long-term debt, number of tranches with modified repayment schedule | tranche							1
Debt instrument, number of repayments reduced | repayment							2
Debt instrument, repayment reduction per payment, amount							$ 96,000
Debt instrument, 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%
Foreign subsidiary borrowings | Euro Interbank Offered Rate (Euribor) | Maximum
Line of Credit Facility [Line Items]
Euribor variable interest rates									4.00%
2018 Credit Agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Fixed charge coverage ratio						1.1
Percent availability under revolving commitment						12.50%
Percentage of stock pledged on credit agreement					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
Accordion feature, increase limit						$ 10,000
Weighted average interest rate, revolving credit facility	3.60%						3.60%		3.90%
Commitment fee percentage						0.25%
Debt issuance costs incurred									$ 212,000
Revolving line of credit, accumulated amortization of debt issuance costs	$ 106,000						$ 106,000		131,000
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%
First And Second Amendment to 2018 Credit Agreement | Revolving credit agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Debt issuance costs incurred									$ 75,000
Export Credit Facility | Revolving credit agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity				$ 5,000,000
Accordion feature, increase limit				$ 35,000,000
Weighted average interest rate, revolving credit facility	3.40%						3.40%		3.69%
Export Credit Facility | Revolving credit agreement | Revolving credit agreement | London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Line Items]
Basis spread on LIBOR				1.25%
Short Term Debt Arrangement For Working Capital Purposes
Line of Credit Facility [Line Items]
Debt instrument, term								6 months
Short-term debt arrangement								$ 1,137,000
Third Amendment To Credit Agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Coverage ratio threshold for three or more business days in consecutive thirty day period			12.50%
Fourth Amendment To Credit Agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Receivables pledged as collateral	$ 24,000,000						$ 24,000,000		$ 24,496,000
Fixed charge coverage ratio						1.1
Percent availability under revolving commitment		10.00%
Coverage ratio threshold for three or more business days in consecutive thirty day period	10.00%	10.00%
Line of credit facility, benchmark of collateral threshold		$ 20,000,000
Line of credit facility, collateral springs	$ 2,400,000						2,400,000
Fourth Amendment To Credit Agreement | Revolving credit agreement | Revolving credit agreement
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity	35,000,000						35,000,000
Remaining borrowing capacity	7,709,000						7,709,000		$ 7,049,000
Line of credit facility, covenant terms, floor		2,000,000
Line of credit facility, benchmark of collateral threshold		$ 20,000,000
Line of credit facility, total commitment springs	$ 3,500,000						$ 3,500,000