Fair Value of Financial Assets and Liabilities - Consideration of Credit Risk and Concentrations (Details) - Credit Concentration Risk $ in Millions	Sep. 30, 2025 USD ($) Counterparty
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure	8
Municipal or Cooperative Entities or Other Utilities [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure	6
External Credit Rating, Investment Grade [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure	2
Wholesale, trading and non-trading commodity credit exposure for the most significant counterparties \| $	$ 3
Percentage of wholesale, trading and non-trading commodity credit exposure for the most significant counterparties (in hundredths)	6.00%
External Credit Rating, Non Investment Grade [Member]
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure	0
Internal Investment Grade
Derivative [Line Items]
Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure	6
Wholesale, trading and non-trading commodity credit exposure for the most significant counterparties \| $	$ 41
Percentage of wholesale, trading and non-trading commodity credit exposure for the most significant counterparties (in hundredths)	75.00%

PUBLIC SERVICE CO OF COLORADO 10-Q