Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

No definition available.

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

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Number of claims dismissed.

+ References

No definition available.

+ Details

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- Definition

Number of claims settled.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Number of plaintiffs that have filed claims pertaining to a loss contingency.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of pending claims pertaining to a loss contingency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of sales claimed by the plaintiff as being subject to refund.

+ References

No definition available.

+ Details

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

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

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Namespace Prefix:	xel_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Loss Contingency, Subset of Cases within Multi-District Litigation, Number

+ References

No definition available.

+ Details

Name:	xel_LossContingencySubsetofCaseswithinMultiDistrictLitigationNumber
Namespace Prefix:	xel_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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Namespace Prefix:
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Commitments and Contingencies, Legal Contingencies (Details)	1 Months Ended		12 Months Ended
	Oct. 31, 2016 USD ($)	Dec. 31, 2015	Dec. 31, 2016 USD ($)	Dec. 31, 2009
Gas Trading Litigation
Legal Contingencies [Abstract]
Loss Contingency, Pending Claims, Number			1	13
Loss Contingency, Claims Settled, Number			5
Loss Contingency, Claims Dismissed, Number			7
Loss Contingency, Subset of Cases within Multi-District Litigation, Number			2
PSCo \| Pacific Northwest FERC Refund Proceeding
Legal Contingencies [Abstract]
Litigation Settlement, Amount	$ 15,000
PSCo \| Line Extension Disputes
Legal Contingencies [Abstract]
Accrual For Legal Contingency			$ 0
Loss Contingency, Number of Plaintiffs			2
NSP-Wisconsin \| Gas Trading Litigation
Legal Contingencies [Abstract]
Loss Contingency, Pending Claims, Number				2
Minimum \| PSCo \| Pacific Northwest FERC Refund Proceeding
Legal Contingencies [Abstract]
Amount Of Sales Claimed As Subject To Refund			$ 34,000,000
Minimum \| PSCo \| Line Extension Disputes
Legal Contingencies [Abstract]
Loss Contingency, Number of Plaintiffs		50
Maximum \| PSCo \| Pacific Northwest FERC Refund Proceeding
Legal Contingencies [Abstract]
Amount Of Sales Claimed As Subject To Refund			$ 50,000,000