The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of a finite-lived intangible asset to fair value.

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Fair Value of Financial Assets and Liabilities (Details 5) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Finite-lived Intangible Assets [Roll Forward]
Net carrying value Patent Portfolios, net			$ 3,578
Amortization expenses	$ (346)	$ (346)	(1,027)	$ (1,027)
Patent Portfolios, net impairment charges	$ 1,051		1,051
Patents [Member]
Finite-lived Intangible Assets [Roll Forward]
Net carrying value Patent Portfolios, net			1,500	$ 3,578	$ 3,578
Amortization expenses			(1,027)
Patent Portfolios, net impairment charges			$ 1,051