Revenues - Additional Information (Detail) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)
Accrued sales returns included in accrued expenses and other current liabilities	$ 14,702	$ 14,702
Product Concentration Risk \| Total Service Revenue \| Maximum
Total service revenue as percentage of consolidated revenues	1.00%	1.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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