The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

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Property, Plant & Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant & Equipment [Line Items]
Proceeds from sales of assets		$ 1,000		$ 1,000	$ 1,234
Property, plant and equipment
Property, Plant & Equipment [Line Items]
Depreciation and amortization	$ 2,500		$ 4,000	$ 5,100	$ 9,100