General - Additional Information (Detail) - USD ($) $ in Millions |
9 Months Ended | 12 Months Ended |
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Sep. 30, 2018 |
Dec. 31, 2017 |
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| Organization Consolidation And Presentation Of Financial Statements [Abstract] | ||
| Derivative effective dates | Aug. 12, 2015 | |
| Sales returns reserve | $ 42.6 | $ 43.4 |
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- Definition Derivative effective dates. No definition available.
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- References No definition available.
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- Definition Amount of estimated sales returns. Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
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