XML 82 R67.htm IDEA: XBRL DOCUMENT
v3.20.4

Retirement Benefit Plans - Asset Allocation of Defined Benefit Pension Plan Assets and Fair Values and Levels in Fair Value Hierarchy (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | $ 21,609 | $ 20,970 | $ 22,052
Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 19,511 | 18,965 |
Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 2,098 | 2,005 | $ 1,815
Large value |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 175 | 435 |
Large value | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 175 | 435 |
Large value | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Large blend |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 9,334 | 9,368 |
Large blend | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 9,334 | 9,368 |
Large blend | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Large growth |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 1,109 | 625 |
Large growth | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 1,109 | 625 |
Large growth | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Mid blend |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 176 | 163 |
Mid blend | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 176 | 163 |
Mid blend | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Small blend |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 224 | 159 |
Small blend | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 224 | 159 |
Small blend | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Foreign large blend |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 1,603 | 1,607 |
Foreign large blend | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 1,603 | 1,607 |
Foreign large blend | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Diversified emerging markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 50 | 17 |
Diversified emerging markets | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 50 | 17 |
Diversified emerging markets | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Inflation protected bond |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 1,028 | 1,100 |
Inflation protected bond | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 1,028 | 1,100 |
Inflation protected bond | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Intermediate term bond |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 7,479 | 6,974 |
Intermediate term bond | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 5,381 | 4,969 |
Intermediate term bond | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 2,098 | 2,005 |
High inflation bond |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 178 | 173 |
High inflation bond | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 178 | 173 |
High inflation bond | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Emerging markets bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 106 | 106 |
Emerging markets bonds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 106 | 106 |
Emerging markets bonds | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 0 | 0 |
Short-term bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 147 | 243 |
Short-term bonds | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 147 | 243 |
Short-term bonds | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | $ 0 | $ 0 |

X
- 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_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_UsEquityLargeValueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_UsEquityLargeBlendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_UsEquityLargeGrowthMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_UsEquityMidBlendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_UsEquitySmallBlendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_NonUsEquitySecuritiesForeignLargeBlendMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_NonUsEquitySecuritiesDiversifiedEmergingMarketMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_UsDebtSecuritiesInflationProtectedBondMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_UsDebtSecuritiesIntermediateTermBondMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_UsDebtSecuritiesHighInflationBondMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_NonUsDebtSecuritiesEmergingMarketBondMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=sif_StableValueShortTermBondMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |