Discontinued Operations - Summary of Operating Results (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Discontinued Operations And Disposal Groups [Abstract]
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Net sales	$ 3,736	$ 11,811		$ 17,899	$ 30,255
Cost of sales	4,326	11,028		20,358	29,716
Gross margin	(590)	783		(2,459)	539
Operating expenses:
Research and development	15	55		100	238
Selling and marketing	329	519		1,561	1,561
General and administrative	683			681
Total operating expenses	1,027	574		2,342	1,799
Income (loss) from discontinued operations	(1,617)	209		(4,801)	(1,260)
Other income (expense):
Interest expense and other, net	6,030	(321)		5,649	(826)
Income (loss) from discontinued operations before income taxes	4,413	(112)		848	(2,086)
Net income (loss) from discontinued operations	$ 4,413	$ (112)		$ 848	$ (2,086)

Disposal group including discontinued operation, interest expense and other, net.

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Disposal group including discontinued operation, other income (expense).

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Disposal group including discontinued operation operating expenses.

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Disposal group including discontinued operation research and development expense.

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Disposal group including discontinued operation selling and marketing expense.

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Amount before tax of income (loss) from a discontinued operation. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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Indicates business segment that includes component or group of components disposed of or classified as held-for-sale representing strategic shift that has or will have major effect on operation and financial result.

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Amount of costs of goods sold attributable to disposal group, including, but not limited to, discontinued operation.

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Amount of general and administrative expense attributable to disposal group, including, but not limited to, discontinued operation.

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Amount of gross profit attributable to disposal group, including, but not limited to, discontinued operation.

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Amount of operating expense attributable to disposal group, including, but not limited to, discontinued operation.

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Amount of operating income (loss) attributable to disposal group, including, but not limited to, discontinued operation.

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