Commitments and Contingencies, Variable Interest Entities (Details) - MW	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Maximum
Purchased Power Agreements (PPAs) [Abstract]
Long term purchased power agreements expiration	2032
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Purchased Power Agreements (PPAs) [Abstract]
Generating capacity (in MW)	1,518	1,442

Generating capacity under long-term purchased power agreements.

No definition available.

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