Overview and significant Accounting Policies (Details 4) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Property, plant and equipment
Equipment and furniture	$ 147,151	$ 158,540
Less accumulated depreciation and amortization	(133,559)	(136,753)
Net property, plant and equipment	$ 13,592	21,787
Minimum
Property, plant and equipment
Estimated useful lives of acquired intangible assets	2 years
Maximum
Property, plant and equipment
Estimated useful lives of acquired intangible assets	10 years
Buildings and improvements \| Minimum
Property, plant and equipment
Estimated useful lives	3 years
Buildings and improvements \| Maximum
Property, plant and equipment
Estimated useful lives	40 years
Software \| Minimum
Property, plant and equipment
Estimated useful lives	2 years
Software \| Maximum
Property, plant and equipment
Estimated useful lives	10 years
Equipment and furniture \| Minimum
Property, plant and equipment
Estimated useful lives	3 years
Equipment and furniture \| Maximum
Property, plant and equipment
Estimated useful lives	20 years
Capital lease assets
Property, plant and equipment
Equipment and furniture	$ 2,658	1,774
Less accumulated depreciation and amortization	(920)	(687)
Net property, plant and equipment	$ 1,738	$ 1,087

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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Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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