v3.26.3
Fair Value of Financial Assets and Liabilities - Recurring Fair Value Measurements (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Derivatives, Fair Value [Line Items]          
Return Cash Collateral $ 0   $ 0   $ 0
Other Derivative Instruments          
Derivatives, Fair Value [Line Items]          
Pre-tax gains (losses) recognized during the period in income 7 $ (2) 5 $ (9)  
Other Derivative Instruments | Natural Gas Commodity          
Derivatives, Fair Value [Line Items]          
Pre-tax gains (losses) recognized during the period in income [1],[2]     (7) $ (9)  
Other Derivative Instruments | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Pre-tax gains (losses) recognized during the period in income [3] 7 $ (2) 12    
Fair Value Measured on a Recurring Basis          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Net [4] 8   8   7
Derivative Liability, Net [4] 5   5   8
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Net 0   0   0
Derivative Liability, Net 1   1   1
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Natural Gas Commodity          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross 8   8   7
Netting [5] 0   0   0
Derivative Asset, Net 8   8   7
Derivative Liability, Gross 4   4   7
Netting [5] 0   0   0
Derivative Liability, Net 4   4   7
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Level 1 | Natural Gas Commodity          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross 0   0   0
Derivative Liability, Gross 0   0   0
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Level 2 | Natural Gas Commodity          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross 8   8   7
Derivative Liability, Gross 4   4   7
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Level 3 | Natural Gas Commodity          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross 0   0   0
Derivative Liability, Gross 0   0   0
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:AssetsCurrent          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross [4] 10   10   13
Netting [4],[5] (2)   (2)   (6)
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:AssetsCurrent | Level 1          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross [4] 0   0   0
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:AssetsCurrent | Level 2          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross [4] 10   10   13
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:AssetsCurrent | Level 3          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross [4] 0   0   0
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:AssetsCurrent | Other Derivative Instruments | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross 2   2   6
Netting [5] (2)   (2)   (6)
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:AssetsCurrent | Other Derivative Instruments | Level 1 | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross 0   0   0
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:AssetsCurrent | Other Derivative Instruments | Level 2 | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross 2   2   6
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:AssetsCurrent | Other Derivative Instruments | Level 3 | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Derivative Asset, Gross 0   0   0
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent          
Derivatives, Fair Value [Line Items]          
Derivative Liability, Gross [4] 7   7   14
Netting [4],[5] (2)   (2)   (6)
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent | Level 1          
Derivatives, Fair Value [Line Items]          
Derivative Liability, Gross [4] 0   0   0
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent | Level 2          
Derivatives, Fair Value [Line Items]          
Derivative Liability, Gross [4] 7   7   14
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent | Level 3          
Derivatives, Fair Value [Line Items]          
Derivative Liability, Gross [4] 0   0   0
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent | Other Derivative Instruments | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Derivative Liability, Gross 3   3   7
Netting [5] (2)   (2)   (6)
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent | Other Derivative Instruments | Level 1 | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Derivative Liability, Gross 0   0   0
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent | Other Derivative Instruments | Level 2 | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Derivative Liability, Gross 3   3   7
Fair Value Measured on a Recurring Basis | Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent | Other Derivative Instruments | Level 3 | Commodity Trading          
Derivatives, Fair Value [Line Items]          
Derivative Liability, Gross $ 0   $ 0   $ 0
[1] Amounts are primarily recorded to cost of natural gas sold and transported. Amounts are subject to cost-recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate.
[2] Relates primarily to option premium amortization.
[3] Recorded to electric revenues. Presented amounts do not reflect non-derivative transactions or margin sharing with customers.
[4] Current derivative assets are included in prepayments and other as of Sept. 30, 2026 and Dec. 31, 2025. Total current derivative liabilities are included in other current liabilities as of Sept. 30, 2026 and Dec. 31, 2025.
[5] PSCo nets derivative instruments and related collateral on its consolidated balance sheets when supported by a legally enforceable master netting agreement. At Sept. 30, 2026 and Dec. 31, 2025, derivative assets and liabilities include no obligations to return cash collateral. At both Sept. 30, 2026 and Dec. 31, 2025, derivative assets and liabilities include immaterial rights to reclaim cash collateral. Counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.