Debt - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Mar. 31, 2015
Debt Instrument [Line Items]
Amount borrowed under revolving credit facility	$ 248.1us-gaap_LineOfCredit
Debt issuance cost	5.0us-gaap_DebtIssuanceCosts
Debt amortization period	60 months
Percentage of voting capital stock	65.00%
Description of Base Rate	The revolving credit facility and term loans bear interest at our election of a Base Rate plus an applicable margin or LIBOR plus an applicable margin. Swingline loans bear interest at a Base Rate plus an applicable margin. The Base Rate is a floating rate that is the greater of the Prime Rate, the Federal Funds Rate plus 50 basis points, or LIBOR plus 100 basis points. The applicable margin is based on a sliding scale which ranges from zero to 100 basis points for Base Rate loans and 100 basis points to 200 basis points for LIBOR loans.
Description of periodic payments	The term loan facility requires repayment over five years with nineteen quarterly principal payments which began in the three months ending March 31, 2015.
Quarterly payment beginning period	Mar. 31, 2015
Final principal payment	90.0
Revolving credit facility maturity period	Sep. 30, 2019
Operating covenant description	Under the Credit Agreement, there are restrictive operating covenants, including three financial covenants which limit the consolidated total leverage ratio, or leverage ratio, the consolidated interest coverage ratio, or interest coverage ratio, and places a restriction on the amount of capital expenditures that may be made in any fiscal year. The leverage ratio is the ratio of debt as of the measurement date to earnings before interest, taxes, depreciation and amortization, or EBITDA, for the four consecutive quarters ending with the quarter of measurement. The leverage ratio must not exceed 2.50 to 1.0 during the first two years of the agreement, and 2.0 to 1.0 during the last three years of the agreement. The interest coverage ratio is EBITDA to interest expense for the four consecutive quarters ending with the quarter of measurement. The interest coverage ratio must not be less than 3.50 to 1.0 during the term of the Credit Agreement.
First Four Quarters [Member]
Debt Instrument [Line Items]
Quarterly principal payment	1.9
Next Fourteen Quarters [Member]
Debt Instrument [Line Items]
Quarterly principal payment	3.8
Federal Funds Effective Swap Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
Base Rate [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.00%
Base Rate [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility amount	150
Amount borrowed under revolving credit facility	100.0
Revolving Credit Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Commitment fee percentage of unused portion	0.25%
Revolving Credit Facility [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Commitment fee percentage of unused portion	0.45%
Revolving Credit Facility and Term Loan [Member]
Debt Instrument [Line Items]
Increase in Line of credit facility	100
Term Loan [Member]
Debt Instrument [Line Items]
Line of credit facility amount	150
Amount borrowed under revolving credit facility	150.0
Letter of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility amount	20
Bridge Loan [Member]
Debt Instrument [Line Items]
Line of credit facility amount	$ 20

Debt instrument amortization period.

No definition available.

Name:	syna_DebtInstrumentAmortizationPeriod
Namespace Prefix:	syna_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility allowable requests for additional borrowing.

+ References

No definition available.

+ Details

Name:	syna_LineOfCreditFacilityAllowableRequestsForAdditionalBorrowing
Namespace Prefix:	syna_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the final principal payment made at the maturity of the credit facility.

+ References

No definition available.

+ Details

Name:	syna_LineOfCreditFacilityFinalPrincipalPayment
Namespace Prefix:	syna_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of voting capital stock of certain foreign subsidiaries collateralized.

+ References

No definition available.

+ Details

Name:	syna_PercentageOfVotingCapitalStockOfCertainForeignSubsidiariesCollateralized
Namespace Prefix:	syna_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of minimum financial levels (for example, tangible net worth and working capital) and achievement of certain financial ratios (for example, working capital ratio and debt service coverage ratio), and adherence to certain clauses which generally require or restrict certain actions (for example, entering into a debt arrangement with equal or greater seniority, and selling or discontinuing a certain business segment or material subsidiary) to be in compliance with the covenant clauses of the debt agreement. May also include a discussion of the adverse consequences that would result if the entity violates or fails to satisfy the covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 470

-Section 50

-Paragraph 3

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentCovenantDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

+ References

No definition available.

+ Details

Name:	us-gaap_DebtIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Date the first payment under the line of credit must be paid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityDateOfFirstRequiredPayment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the frequency of periodic payments, which may be presented in a variety of ways (for example, monthly, quarterly, annually).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityFrequencyOfPayments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of the required periodic payment applied to principal.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityPeriodicPaymentPrincipal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_CreditFacilityAxis=syna_RevolvingCreditFacilityAndTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=syna_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=syna_FirstFourQuartersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=syna_NextFourteenQuartersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_BridgeLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_FederalFundsEffectiveSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: