Details of Selected Balance Sheet Accounts - Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials and subassemblies	$ 18,128	$ 18,509
Work-in-process	2,068	2,079
Finished goods	4,568	4,932
Less: reserve for excess and obsolete inventories	(12,902)	(13,333)
Inventories, net	$ 11,862	$ 12,187

Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Gross amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed.

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Amount of valuation reserve for inventory.

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Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer.

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