| Commitments, Contingencies and Litigation - Additional Information (Detail) | 9 Months Ended | 
|---|---|
| Sep. 30, 2017 | |
| Pending Litigation [Member] | The Complaint [Member] | |
| Loss Contingencies [Line Items] | |
| Lawsuit Filing Date | Nov. 08, 2016 | 
| X | ||||||||||
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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| X | ||||||||||
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- Definition States the date the complaint was formally filed in a court of law, in arbitration or mediation. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Details 
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| X | ||||||||||
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- Details 
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