Name:	sr_NonmonetaryNotionalAmountOfNaturalGasDerivativeContractsNotDesignatedAsNormalPurchasesOrNormalSales
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Notional amount of non-exchange traded natural gas commodity contracts to be settled in next twelve months.

No definition available.

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Notional amount of non-exchange traded natural gas commodity contracts to be settled in year five.

No definition available.

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Notional amount of non-exchange traded natural gas commodity contracts to be settled in year four.

No definition available.

Name:	sr_NotionalAmountOfNonExchangeTradedNaturalGasCommodityContractsToBeSettledInYearFour
Namespace Prefix:	sr_
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Notional amount of non-exchange traded natural gas commodity contracts to be settled in year three.

No definition available.

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Notional amount of non-exchange traded natural gas commodity contracts to be settled in year two.

No definition available.

Name:	sr_NotionalAmountOfNonExchangeTradedNaturalGasCommodityContractsToBeSettledInYearTwo
Namespace Prefix:	sr_
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Fixed interest rate related to the interest rate derivative.

No definition available.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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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.

No definition available.

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Amount of decrease in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

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Data Type:	xbrli:monetaryItemType
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Nominal or face amount used to calculate payment on derivative.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

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Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_DerivativeTermOfContract
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Data Type:	xbrli:durationItemType
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Period Type:	duration

Amount of other receivables due from broker-dealers or clearing organizations.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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