Name:	us-gaap_GuaranteeObligationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248

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

Describe the approximate term of the guarantee or each group of similar guarantees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248

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The amount of assets held either as collateral or by third parties that, upon the occurrence of any triggering event or condition under the guarantee, the guarantor can obtain and liquidate to recover all or a portion of the amounts paid under the guarantee.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Current estimate of exposure under the guarantee or each group of similar guarantees before reduction for potential recoveries.

No definition available.

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of claims made under the terms of the guarantee as of the balance sheet date.

No definition available.

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Namespace Prefix:	xel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The legal entity responsible for providing the guarantee.

No definition available.

Name:	xel_GuaranteeObligationsGuarantor
Namespace Prefix:	xel_
Data Type:	xbrli:stringItemType
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Period Type:	duration

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Name:	us-gaap_UnderlyingAssetClassAxis=xel_ObligationsunderequipmentleaseMember
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