Select balance sheet data - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 279,807	$ 289,063
Less accumulated depreciation	171,920	164,000
Total property, plant and equipment, net	107,887	125,063
Land [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 1,033	1,264
Property, plant and equipment useful lives	Indefinite
Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 3,169	3,169
Land Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful lives	15 years
Land Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful lives	39 years
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 55,022	58,021
Building and Building Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful lives	15 years
Building and Building Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful lives	39 years
Machinery, Equipment and Tooling [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 198,951	204,248
Machinery, Equipment and Tooling [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful lives	3 years
Machinery, Equipment and Tooling [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful lives	10 years
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 3,712	3,738
Property, plant and equipment useful lives	5 years
Office Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 16,243	15,469
Office Furniture and Fixtures [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful lives	3 years
Office Furniture and Fixtures [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment useful lives	7 years
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 1,677	$ 3,154

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment).

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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