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Fair Value - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Fair Value Disclosures [Line Items]
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Transfer amount of assets or liabilities of level three	0syna_FairValueMeasurementsTransfersIntoOrOutOfLevelThree	0syna_FairValueMeasurementsTransfersIntoOrOutOfLevelThree	0syna_FairValueMeasurementsTransfersIntoOrOutOfLevelThree	0syna_FairValueMeasurementsTransfersIntoOrOutOfLevelThree
Validity Sensors, Inc [Member]
Fair Value Disclosures [Line Items]
Additional consideration	130,900,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh / us-gaap_BusinessAcquisitionAxis = syna_ValiditySensorsIncMember		130,900,000us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh / us-gaap_BusinessAcquisitionAxis = syna_ValiditySensorsIncMember
Pacinian [Member]
Fair Value Disclosures [Line Items]
Additional consideration paid to former stockholders based on sales of products, due	10,000,000syna_BusinessCombinationContingentConsiderationArrangementsContingentConsiderationObligationToFormerShareholdersOfAcquiree / us-gaap_BusinessAcquisitionAxis = syna_PacinianMember		10,000,000syna_BusinessCombinationContingentConsiderationArrangementsContingentConsiderationObligationToFormerShareholdersOfAcquiree / us-gaap_BusinessAcquisitionAxis = syna_PacinianMember
Prepaid Expenses and Other Current Assets [Member] | Auction Rate Securities [Member]
Fair Value Disclosures [Line Items]
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Amount of investments in debt securities classified as available-for-sale, expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

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-Topic 320

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