Joint Ownership of Generation, Transmission and Gas Facilities (Details) $ in Thousands	12 Months Ended
Dec. 31, 2015 USD ($) MW
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 1,508,884
Accumulated depreciation	370,531
Construction work in progress	$ 37,182
Generating capacity (in MW) \| MW	820
Electric Generation \| Hayden Unit 1
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 155,159
Accumulated depreciation	69,679
Construction work in progress	$ 147
Ownership percentage (in hundredths)	76.00%
Electric Generation \| Hayden Unit 2
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 121,486
Accumulated depreciation	61,780
Construction work in progress	$ 20,840
Ownership percentage (in hundredths)	37.00%
Electric Generation \| Hayden Common Facilities
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 37,756
Accumulated depreciation	17,910
Construction work in progress	$ 321
Ownership percentage (in hundredths)	53.00%
Electric Generation \| Craig Units 1 and 2
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 60,158
Accumulated depreciation	36,570
Construction work in progress	$ 8,518
Ownership percentage (in hundredths)	10.00%
Electric Generation \| Craig Common Facilities 1, 2 and 3
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 37,418
Accumulated depreciation	18,520
Construction work in progress	$ 505
Ownership percentage (in hundredths)	7.00%
Electric Generation \| Comanche Unit 3
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 892,340
Accumulated depreciation	95,029
Construction work in progress	$ 452
Ownership percentage (in hundredths)	67.00%
Electric Generation \| Comanche Common Facilities
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 23,826
Accumulated depreciation	1,430
Construction work in progress	$ 894
Ownership percentage (in hundredths)	82.00%
Electric Transmission \| Transmission and other facilities, including substations
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 152,460
Accumulated depreciation	62,324
Construction work in progress	$ 5,378
Ownership percentage of group of jointly owned facilities	Various
Gas Transportation \| Rifle to Avon
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 19,928
Accumulated depreciation	7,165
Construction work in progress	$ 0
Ownership percentage (in hundredths)	60.00%
Gas Transportation \| Gas Transportation Compressor [Member]
Jointly Owned Utility Plant [Abstract]
Plant in service	$ 8,353
Accumulated depreciation	124
Construction work in progress	$ 127
Ownership percentage (in hundredths)	50.00%

The entity's generating capacity of the jointly owned facilities.

No definition available.

Name:	psco_JointlyOwnedGeneratingCapacity
Namespace Prefix:	psco_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Jointly Owned Utility Plant Proportionate Ownership Percentage Share

+ References

No definition available.

+ Details

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

- Definition

The period end amount owned by the reporting utility of a jointly owned utility plant in service.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 360
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 10.C)
-URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 10
-Section C

+ Details

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

- References

No definition available.

+ Details

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

- Definition

The period end amount of construction work in progress at a jointly owned electricity generation plant.

+ References

+ Details

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

- Definition

The period end amount of accumulated depreciation in a jointly owned electricity generation plant.

+ References

+ Details

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

- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

+ References

+ Details

Name:	us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_JointlyOwnedUtilityPlantAxis=us-gaap_JointlyOwnedElectricityGenerationPlantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_HaydenUnit1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_HaydenUnit2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_HaydenCommonFacilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_CraigUnits1And2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_CraigCommonFacilities12And3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_ComancheUnit3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_ComancheCommonFacilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_JointlyOwnedUtilityPlantAxis=us-gaap_JointlyOwnedElectricityTransmissionAndDistributionSystemMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_TransmissionandOtherFacilitiesincludingSubstationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_JointlyOwnedUtilityPlantAxis=us-gaap_GasTransmissionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_RifleToAvonMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	psco_JointlyOwnedUtilityPlantNameAxis=psco_GasTransportationCompressorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: