XML 101 R86.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Pension and Other Post-retirement Benefits - Fair Value Measurement of Plan Assets (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | $ 18.5 | $ 20.2 |
Non-investment plan assets | 0.1 | 0.1 |
Total plan assets | 18.6 | 20.3 |
Short-term investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.2 | 0.2 |
Common stocks |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 2.3 | 2.5 |
U.S. Treasury securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 6.5 | 6.7 |
Other fixed income securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 7.4 | 7.4 |
Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 1.2 | 1.0 |
Private equity |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.9 | 2.4 |
Quoted Prices in Active Markets for Identical Contracts (Level 1) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 3.3 | 3.3 |
Quoted Prices in Active Markets for Identical Contracts (Level 1) | Short-term investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.2 | 0.2 |
Quoted Prices in Active Markets for Identical Contracts (Level 1) | Common stocks |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 2.3 | 2.5 |
Quoted Prices in Active Markets for Identical Contracts (Level 1) | U.S. Treasury securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.8 | 0.6 |
Quoted Prices in Active Markets for Identical Contracts (Level 1) | Other fixed income securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Quoted Prices in Active Markets for Identical Contracts (Level 1) | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Quoted Prices in Active Markets for Identical Contracts (Level 1) | Private equity |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Significant Other Observable Inputs (Level 2) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 14.3 | 14.5 |
Significant Other Observable Inputs (Level 2) | Short-term investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Significant Other Observable Inputs (Level 2) | Common stocks |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Significant Other Observable Inputs (Level 2) | U.S. Treasury securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 5.7 | 6.1 |
Significant Other Observable Inputs (Level 2) | Other fixed income securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 7.4 | 7.4 |
Significant Other Observable Inputs (Level 2) | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 1.2 | 1.0 |
Significant Other Observable Inputs (Level 2) | Private equity |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Significant Non- observable Inputs (Level 3) |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.9 | 2.4 |
Significant Non- observable Inputs (Level 3) | Short-term investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Significant Non- observable Inputs (Level 3) | Common stocks |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Significant Non- observable Inputs (Level 3) | U.S. Treasury securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Significant Non- observable Inputs (Level 3) | Other fixed income securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Significant Non- observable Inputs (Level 3) | Mutual funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | 0.0 | 0.0 |
Significant Non- observable Inputs (Level 3) | Private equity |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Total fair value of plan asset investments | $ 0.9 | $ 2.4 | $ 2.2

X
- Definition Defined benefit plan fair value of non-investment plan assets. + References No definition available. + Details
Name: | aos_DefinedBenefitPlanFairValueOfNonInvestmentPlanAssets
Namespace Prefix: | aos_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Defined Benefit Plan Fair Value of Plan Assets Including Non-Investment Plan Assets + References No definition available. + Details
Name: | aos_DefinedBenefitPlanFairValueOfPlanAssetsIncludingNoninvestmentPlanAssets
Namespace Prefix: | aos_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 55 -Paragraph 17 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480482/715-20-55-17 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

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

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

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

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

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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: |