Debt Instrument Borrowing Period

No definition available.

Name:	isil_DebtInstrumentBorrowingPeriod
Namespace Prefix:	isil_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Potential Incremental Borrowing Capacity Upon Request.

+ References

No definition available.

+ Details

Name:	isil_PotentialIncrementalBorrowingCapacityUponRequest
Namespace Prefix:	isil_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

Date the debt instrument was issued, 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 210.5-02.22(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, 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 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- 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 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

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 20, 22
-Article 5

+ Details

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

- 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

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

+ Details

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

- Details

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Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=isil_PreviousTermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=isil_PreviousRevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=isil_SwingLineLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=isil_MulticurrencyBorrowingsMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=isil_EurodollarBorrowingPeriodOneMember
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Period Type:

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 01, 2016	Jan. 02, 2015	Sep. 01, 2011	Aug. 31, 2011
Debt Instrument [Line Items]
Outstanding letters of credit	$ 1.3	$ 1.3
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Term of credit facility	5 years
Debt instrument, issuance date	Sep. 01, 2011
Credit facility maximum borrowing capacity			$ 325.0
Debt instrument maturity date	Sep. 01, 2016
Increase in additional borrowing capacity	$ 75.0
Credit facility outstanding borrowings	0.0	$ 0.0
Standby Letters of Credit [Member]
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 25.0
Previous Term-Loan Facility \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Term of credit facility	6 years
Credit facility maximum borrowing capacity				$ 300.0
Previous Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity				$ 75.0
Swing Line Loans [Member]
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 10.0
Multicurrency Borrowings [Member]
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 50.0
Eurodollar Borrowing Period One [Member]
Debt Instrument [Line Items]
Debt instrument borrowing period	1 month
Eurodollar Borrowing Period Two [Member]
Debt Instrument [Line Items]
Debt instrument borrowing period	2 months
Eurodollar Borrowing Period Three [Member]
Debt Instrument [Line Items]
Debt instrument borrowing period	3 months
Eurodollar Borrowing Period Four [Member]
Debt Instrument [Line Items]
Debt instrument borrowing period	6 months
Eurodollar Borrowing Period Five [Member]
Debt Instrument [Line Items]
Debt instrument borrowing period	12 months
Eurocurrency Rate Loans
Debt Instrument [Line Items]
Debt instrument variable interest rate	1.00%
Eurocurrency Rate Loans \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate	1.75%
Eurocurrency Rate Loans \| Maximum [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate	2.75%
Base Rate Loans
Debt Instrument [Line Items]
Debt instrument variable interest rate	0.50%
Base Rate Loans \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate	0.75%
Base Rate Loans \| Maximum [Member]
Debt Instrument [Line Items]
Debt instrument variable interest rate	1.75%