Supply Chain Finance Program (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Payables and Accruals [Abstract]
Termination notice period (at least)	30 days
Termination notice period by financial institution (at least)	10 days
Supply chain finance program, payment period (up to)	210 days
Supplier chain finance program obligation, current	$ 385.8	$ 303.7	$ 284.2
Supplier Finance Program, Obligation, Current, Statement of Financial Position [Extensible Enumeration]	Trade accounts payable	Trade accounts payable	Trade accounts payable

Supplier Finance Program, Termination Notice Period

No definition available.

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Balance Type:	na
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- Definition

Supplier Finance Program, Termination Notice Period By Financial Institution

+ References

No definition available.

+ Details

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Namespace Prefix:	slgn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

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

- Definition

Amount of obligation for supplier finance program, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479468/405-50-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479468/405-50-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479468/405-50-50-4

+ Details

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

- Definition

Indicates line item in statement of financial position that includes obligation for supplier finance program, classified as current.

+ References

+ Details

Name:	us-gaap_SupplierFinanceProgramObligationCurrentStatementOfFinancialPositionExtensibleEnumeration
Namespace Prefix:	us-gaap_
Data Type:	enum2:enumerationSetItemType
Balance Type:	na
Period Type:	instant

- Definition

Period when payment is expected to be made to finance provider or intermediary in supplier finance program, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 405
-SubTopic 50
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479468/405-50-50-3

+ Details

Name:	us-gaap_SupplierFinanceProgramPaymentTimingPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant