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Gas Cost Adjustment NOPR (Details) - USD ($) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2018 | Sep. 30, 2021
Public Utilities, General Disclosures [Line Items] |  |
recoverability of costs in excess of forecasted amount - low end |  | 9000.00%
recoverability of costs in excess of forecasted amount - high end |  | 9500.00%
SPS | Southwest Power Pool (SPP) | SPP Open Access Transmission Tariff Upgrade Costs |  |
Public Utilities, General Disclosures [Line Items] |  |
Public Utilities, Billed Charges For Transmission Service Upgrades | $ 13 |

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