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Revenue Recognition - Additional Information (Detail) | 6 Months Ended
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Dec. 31, 2017 Time
Revenue Recognition [Abstract] |
Stock rotation rights of inventory per year for distributors | 2

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- Definition Stock rotation rights for inventory per year. + References No definition available. + Details
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Namespace Prefix: | syna_
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Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_RevenueRecognitionAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration