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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Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Finite-lived intangible assets
Intangible assets, gross	$ 6,074		$ 6,074		$ 6,015
Less accumulated amortization	(4,916)		(4,916)		(4,532)
Intangible assets, net	1,158		1,158		1,483
Amortization of intangible assets	100	$ 100	300	$ 300
Trade name
Finite-lived intangible assets
Intangible assets, gross	1,209		1,209		1,204
Patents and know-how
Finite-lived intangible assets
Intangible assets, gross	4,113		4,113		4,090
Customer relationships
Finite-lived intangible assets
Intangible assets, gross	$ 752		$ 752		$ 721
Minimum \| Trade name
Finite-lived intangible assets
Useful life			15 years
Minimum \| Patents and know-how
Finite-lived intangible assets
Useful life			5 years
Minimum \| Customer relationships
Finite-lived intangible assets
Useful life			4 years
Maximum \| Trade name
Finite-lived intangible assets
Useful life			20 years
Maximum \| Patents and know-how
Finite-lived intangible assets
Useful life			12 years
Maximum \| Customer relationships
Finite-lived intangible assets
Useful life			8 years