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Non-current Investments - Additional Information (Detail) (USD $) | 6 Months Ended
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Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items] |
Auction Rate Securities with fair value maturing from 2016 to 2018 | 12,500,000 syna_AuctionRateSecuritiesWithFairValueMaturingWithinSpecifiedPeriod
Auction Rate Securities with fair value having no stated maturity | 2,800,000 syna_AuctionRateSecuritiesWithFairValueHavingNoStatedMaturity
ARS investments, investment grade | 600,000 syna_AuctionRateSecuritiesAtInvestmentGrade
ARS investments, below investment grade | 18,500,000 syna_AuctionRateSecuritiesBelowInvestmentGrade
Minimum [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Maturity period one | 2016
Maximum [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Maturity period one | 2018
Auction Rate Securities [Member] |
Schedule of Available-for-sale Securities [Line Items] |
ARS investments redeemed at par | 4,900,000 us-gaap_AvailableforsaleSecuritiesSoldAtPar / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AuctionRateSecuritiesMember

X
- Definition Auction rate securities at investment grade. + References No definition available. + Details
Name: | syna_AuctionRateSecuritiesAtInvestmentGrade
Namespace Prefix: | syna_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Auction rate securities below investment grade. + References No definition available. + Details
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Namespace Prefix: | syna_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Auction rate securities maturing year of specified amount one. + References No definition available. + Details
Name: | syna_AuctionRateSecuritiesMaturingYearOfSpecifiedAmountOne
Namespace Prefix: | syna_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Auction rate securities with fair value having no stated maturity. + References No definition available. + Details
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Namespace Prefix: | syna_
Data Type: | xbrli:monetaryItemType
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- Definition Auction rate securities with fair value maturing within specified period. + References No definition available. + Details
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X
- Definition The aggregate value of securities held, which were categorized neither as trading nor held-to-maturity, for which the interest rate reset through an auction process, that failed to be liquidated through auction, and which were sold at par value during the period. + References No definition available. + Details
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- Details
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- Details
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