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Non-current Investments - ARS Investments (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2014 | Jun. 30, 2014
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Investments, Debt and Equity Securities [Abstract] |  |
Investment securities accretion | $ 1.9 syna_AccretionOnInvestmentSecurities | $ 1.3 syna_AccretionOnInvestmentSecurities

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- Definition Accretion on investment securities. + References No definition available. + Details
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Namespace Prefix: | syna_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration