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Postretirement Benefit Plans - Defined Contribution Plans - Additional Information (Detail) | Sep. 30, 2017 USD ($)
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Defined Contribution Plans [Member] |
Defined Contribution Plan Disclosure [Line Items] |
Balance of trust assets | $ 1,502,000

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- Definition Balance of the trust assets. + References No definition available. + Details
Name: | scl_BalanceOfTrustAssets
Namespace Prefix: | scl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |