Debt Instrument, Deferral Term

No definition available.

Name:	sif_DebtInstrumentDeferralTerm
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- Definition

Line Of Credit Facility, Accordion Feature, Increase Limit

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line Of Credit Facility, Availability Of Revolving Commitment, Fixed Charge Coverage Ratio Threshold

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Line of Credit Facility, Covenant Terms, Fixed Charge Coverage Ratio

+ References

No definition available.

+ Details

Name:	sif_LineOfCreditFacilityCovenantTermsFixedChargeCoverageRatio
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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Line of Credit Facility, Stock Pledged, Non-U.S. Subsidiaries, Percentage

+ References

No definition available.

+ Details

Name:	sif_LineOfCreditFacilityStockPledgedNonU.S.SubsidiariesPercentage
Namespace Prefix:	sif_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number Of Customer Invoices Factored

+ References

No definition available.

+ Details

Name:	sif_NumberOfCustomerInvoicesFactored
Namespace Prefix:	sif_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of accumulated amortization of debt issuance costs related to line of credit arrangements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section S45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68176171&loc=SL68176184-208336

+ Details

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

- 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

Amount of assets pledged to secure a debt instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentCollateralAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
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+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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

- Definition

The effective interest rate at the end of the reporting period.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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+ Details

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Balance Type:	na
Period Type:	instant

- 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

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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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

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+ Details

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

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

+ Details

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Period Type:	instant

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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+ Details

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

- Details

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Balance Type:
Period Type:

- Details

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Period Type:

- Details

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- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=sif_A2018CreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
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_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=sif_FourthAmendmentToCreditAgreementMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=sif_ExportCreditFacilityMember
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Period Type:

- Details

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Period Type:

- Details

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Period Type:

- Details

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Namespace Prefix:
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- Details

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Debt - Narrative (Details)			3 Months Ended	12 Months Ended
Debt - Narrative (Details)	Apr. 10, 2020 USD ($)	Sep. 20, 2019	Dec. 31, 2020 USD ($) invoice	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 17, 2018 USD ($)	Aug. 08, 2018 USD ($)
Line of Credit Facility [Line Items]
Number of customer invoices factored \| invoice			1
Foreign subsidiary borrowings
Line of Credit Facility [Line Items]
Receivables pledged as collateral			$ 955,000	$ 1,859,000
Remaining debt balance			$ 7,883,000	5,759,000
Foreign subsidiary borrowings \| Euribor \| Minimum
Line of Credit Facility [Line Items]
Euribor variable interest rates			1.00%
Foreign subsidiary borrowings \| Euribor \| Maximum
Line of Credit Facility [Line Items]
Euribor variable interest rates			4.20%
2018 Credit Agreement \| Revolving credit agreement
Line of Credit Facility [Line Items]
Percentage of stock pledged on credit agreement		66.67%
Fixed charge coverage ratio			1.1
Percent availability under revolving commitment			12.50%
2018 Credit Agreement \| Revolving credit agreement \| Revolving credit agreement
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity							$ 30,000,000
Accordion feature, increase limit							$ 10,000,000
Weighted average interest rate, revolving credit facility			1.70%
Commitment fee percentage			0.25%
Debt issuance costs incurred			$ 212,000
Revolving line of credit, accumulated amortization of debt issuance costs			$ 229,000	$ 205,000
2018 Credit Agreement \| Revolving credit agreement \| Revolving credit agreement \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on LIBOR			1.50%
Fourth Amendment to Credit Agreement \| Revolving credit agreement
Line of Credit Facility [Line Items]
Percent availability under revolving commitment			12.50%	12.50%
Receivables pledged as collateral			$ 26,724,000	$ 26,964,000
Fourth Amendment to Credit Agreement \| Revolving credit agreement \| Revolving credit agreement
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity			35,000,000	35,000,000
Remaining borrowing capacity			$ 16,767,000	$ 13,284,000
Export Credit Facility \| Revolving credit agreement \| Revolving credit agreement
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity						$ 5,000,000
Weighted average interest rate, revolving credit facility			1.20%	1.20%
Export Credit Facility \| Revolving credit agreement \| Revolving credit agreement \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on LIBOR			1.00%
PPP Loan \| Unsecured Promissory Note
Line of Credit Facility [Line Items]
Debt instrument, term	2 years
Face amount	$ 5,025,000
Interest rate	0.98%
Deferral term	6 months
First And Second Amendment to 2018 Credit Agreement \| Revolving credit agreement \| Revolving credit agreement
Line of Credit Facility [Line Items]
Debt issuance costs incurred					$ 75,000
JPMorgan Chase Bank, N.A. \| PPP Loan \| Unsecured Promissory Note
Line of Credit Facility [Line Items]
Repayment debt				$ 261,000
Remaining debt balance			$ 4,764,000	$ 4,764,000