Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Accumulated impairment loss	$ 8,300,000		$ 8,300,000
Aggregate amortization expense	10,500,000	$ 7,000,000.0	29,400,000	$ 19,400,000
Intangible asset impairment charge	657,000	$ 0	$ 657,000	$ 0
Quellent, LLC
Finite-Lived Intangible Assets [Line Items]
Intangible asset impairment charge	$ 657,000

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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Total loss recognized during the period from the impairment of goodwill plus the loss recognized in the period resulting from the impairment of the carrying amount of intangible assets, other than goodwill.

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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