Commitments and Contingencies, Purchased Power Agreements (Details) - Independent Power Producing Entities - MW	3 Months Ended	12 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Purchased Power Agreements [Abstract]
Generating capacity under long term purchased power agreements (in MW)	1,571	1,571
Purchase Power Agreement Expiration (year)	2032	2032

The expiration of purchase power agreements currently under contract (year).

No definition available.

Name:	psco_PurchasePowerAgreementExpiration
Namespace Prefix:	psco_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration