Long-Term Debt - 2 1/4% Senior Notes (Details) - 2¼% Senior Notes	Feb. 26, 2020	Sep. 30, 2020
Debt Instrument [Line Items]
Senior note interest rate (in percentage)		2.25%
Debt Instrument, Redemption - Post March 1 2023
Debt Instrument [Line Items]
Initial redemption price (in percentage)	101.125%
Final redemption price (in percentage)	100.00%
Debt Instrument, Redemption - Pre March 1 2023
Debt Instrument [Line Items]
Maximum redemption percent allowed and limited to proceeds from equity offering (in percentage)	35.00%
Debt redemption, price percent of principal amount, from the proceeds of certain equity offerings (in percentage)	102.25%
Debt instrument, redemption price, (in percentage)	100.00%
Redemption price percent if change in control occurs (in percentage)	101.00%

Debt Instrument, Redemption Price, Percentage, Ending

No definition available.

Name:	slgn_DebtInstrumentRedemptionPricePercentageEnding
Namespace Prefix:	slgn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Redemption Price, Percentage, Initial

+ References

No definition available.

+ Details

Name:	slgn_DebtInstrumentRedemptionPricePercentageInitial
Namespace Prefix:	slgn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Redemption, Price Percent Of Principal Amount, From the Proceeds of Certain Equity Offerings

+ References

No definition available.

+ Details

Name:	slgn_DebtRedemptionPricePercentOfPrincipalAmountFromtheProceedsofCertainEquityOfferings
Namespace Prefix:	slgn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum Redemption Percent Allowed And Limited To Proceeds From Equity Offering

+ References

No definition available.

+ Details

Name:	slgn_MaximumRedemptionPercentAllowedAndLimitedToProceedsFromEquityOffering
Namespace Prefix:	slgn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Redemption Price Percent If Change in Control Occurs

+ References

No definition available.

+ Details

Name:	slgn_RedemptionPricePercentIfChangeinControlOccurs
Namespace Prefix:	slgn_
Data Type:	num:percentItemType
Balance Type:	na
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

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ 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 e
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=slgn_TwoAndOneQuarterPercentSeniorNotesDue2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=slgn_DebtInstrumentRedemptionPeriodPostMarch12023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=slgn_DebtInstrumentRedemptionPreMarch12023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: