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 of intangible assets, excluding goodwill, acquired at the acquisition date.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Goodwill and Other Intangible Assets - Textual (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2017	Aug. 31, 2016
Goodwill [Line Items]
Amortization of intangible assets	$ 4.7	$ 3.3	$ 3.4
Technology-based intangible assets [Member]
Goodwill [Line Items]
Finite-lived intangible asset, useful life	15 years
Customer-related intangible assets [Member]
Goodwill [Line Items]
Finite-lived intangible asset, useful life	11 years
Well Service Group, Inc. and Utility Access Solutions, Inc. (WSG) [Member]
Goodwill [Line Items]
Intangible assets				$ 27.0
Pragmatic Drilling Fluids Additives, Ltd [Member]
Goodwill [Line Items]
Intangible assets					$ 1.7