Commitments and Contingencies, Legal Contingencies (Details)	3 Months Ended
Mar. 31, 2016 USD ($) Factor
Pacific Northwest FERC Refund Proceeding
Legal Contingencies [Abstract]
Estimated City of Seattle's claim for refunds not including interest	$ 28,000,000
Number of factors considered in assessment \| Factor	2
Accrual for legal contingency	$ 0
Line Extension Disputes
Legal Contingencies [Abstract]
Accrual for legal contingency	0
Maximum \| Pacific Northwest FERC Refund Proceeding
Legal Contingencies [Abstract]
Minimum amount of damages claimed by plaintiff	50,000,000
Minimum \| Pacific Northwest FERC Refund Proceeding
Legal Contingencies [Abstract]
Minimum amount of damages claimed by plaintiff	$ 34,000,000

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

No definition available.

Name:	psco_AmountOfSalesClaimedAsSubjectToRefund
Namespace Prefix:	psco_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	psco_LegalContingenciesAbstract
Namespace Prefix:	psco_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of factors considered in the assessment of estimating an amount or range of reasonably possible loss by the entity.

+ References

No definition available.

+ Details

Name:	psco_NumberOfFactorsConsideredInAssessment
Namespace Prefix:	psco_
Data Type:	xbrli:integerItemType
Balance Type:	na
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

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

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ 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 (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

+ Details

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

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=psco_PacificNorthwestFercRefundProceedingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=psco_LineExtensionDisputesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: