XML 50 R39.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Auction Rate Securities - ARS Investments (Parenthetical) (Detail) - USD ($) $ in Millions | Sep. 30, 2016 | Jun. 30, 2016
--- | --- | ---
Investments Debt And Equity Securities [Abstract] |  |
Investment securities accretion | $ 4.7 | $ 4.4

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

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