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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
-Paragraph 28
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Section 50
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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Goodwill and Other Intangible Assets (Details Textual) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization	$ 5,587	$ 6,346	$ 3,065	$ 11,933	$ 6,129
Aggregate amortization expense 2019	18,700			18,700
Aggregate amortization expense 2020	14,600			14,600
Aggregate amortization expense 2021	10,800			10,800
Aggregate amortization expense 2022	7,500			7,500
Aggregate amortization expense 2023	$ 1,400			$ 1,400
Scenario, Forecast
Finite-Lived Intangible Assets [Line Items]
Intangible asset amortization						$ 22,500