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Income Taxes Other Income Tax Matters (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Income Tax [Line Items] |  |  |  |  |
Tax Credit Carryforward, Amount |  | $ 1,519 | $ 1,644 |  |
State NOL carryforwards |  | 9 | 11 |  |
Valuation allowances for state NOL carryforwards |  | (2) | (2) |  |
state tax credit carryforward, net of federal detirment | [1] | 70 | 74 |  |
valuation allowances for state credit carryforwards, net of federal benefit | [2] | (58) | (60) |  |
Federal detriment |  | 19 | 20 |  |
Federal Benefit |  | $ 16 | $ 16 |  |
Federal statutory rate |  | 21.00% | 21.00% |  | 21.00%
State income tax on pretax income, net of federal tax effect |  | 4.80% | 4.90% |  | 4.90%
Effective Income Tax Rate Reconciliation, Tax Credit, Percent | [3] | (43.20%) | (28.10%) |  | (27.40%)
Effective Income Tax Rate Reconciliation, Other Regulatory Items, Percent | [4] | (7.30%) | (5.60%) |  | (5.50%)
Other tax credits, net NOL & tax credit allowances |  | (1.30%) | (1.30%) |  | (1.30%)
Other, net |  | (0.20%) | 0.10% |  | (0.10%)
Effective income tax rate |  | (26.20%) | (9.00%) |  | (8.40%)
Total income tax benefit |  | $ (402) | $ (146) |  | $ (135)
Deferred tax expense (benefit) excluding items below |  | 434 | 129 |  | (138)
Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities |  | (201) | (188) |  | 8
Income Tax Expense (Benefit), Intraperiod Tax Allocation |  | (8) | 0 |  | (10)
Deferred tax benefit |  | (464) | (249) |  | (140)
Regulatory liabilities |  | 1,094 |  |  |
Tax Credit Carryforward, Valuation Allowance |  | (14) | (10) |  |
Adjustments to deferred income taxes for wind production tax credit cash transfers | [5] | (689) | (190) |  | 0
income tax expense |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |
Current federal tax expense |  | 36 | 113 |  | 1
Current state tax expense |  | 28 | 16 |  | 3
Current change in unrecognized tax expense (benefit) |  | 2 | (21) |  | 5
Deferred federal tax benefit |  | (510) | (331) |  | (239)
Deferred state tax expense |  | 46 | 75 |  | 96
Deferred change in unrecognized tax expense |  | 0 | 7 |  | 3
Deferred ITCs |  | (4) | (5) |  | (4)
Total income tax benefit |  | (402) | (146) |  | $ (135)
Net Deferred Tax Liablility [Member] |  |  |  |  |
Income Tax [Line Items] |  |  |  |  |
Tax Credit Carryforward, Amount |  | 1,589 | 1,718 | [6] |
Differences between book and tax bases of property |  | 7,008 | 6,744 | [6] |
Operating Lease Assets |  | 282 | 327 | [6] |
Regulatory Asset |  | 566 | 523 | [6] |
Deferred fuel costs |  | 0 | 67 | [6] |
Deferred tax liability - Pension expense |  | 155 | 151 | [6] |
Other |  | 97 | 80 | [6] |
Total deferred tax liabilities |  | 8,108 | 7,892 | [6] |
Regulatory Liability |  | 751 | 715 | [6] |
Operating Loss Carryforwards |  | 1 | 0 | [6] |
Tax Credit Carryforward, Valuation Allowance |  | (73) | (70) | [6] |
other employee benefits |  | 102 | 117 | [6] |
Other |  | 126 | 184 | [6] |
Total deferred tax assets |  | 2,789 | 3,007 | [6] |
Net deferred tax liability |  | 5,319 | 4,885 | [6] |
Operating lease liabilities |  | 282 | 327 | [6] |
Deferred investment tax credits |  | $ 11 | $ 16 | [6] |
[1] | State tax credit carryforwards are net of federal detriment of $19 million and $20 million as of Dec. 31, 2024 and 2023, respectively.
[2] | Valuation allowances for state tax credit carryforwards were net of federal benefit of $16 million as of Dec. 31, 2024 and 2023.
[3] | Wind, Solar and Nuclear PTCs (net of estimated transfer discounts) are generally credited to customers (reduction to revenue) and do not materially impact earnings. Nuclear PTCs, newly available in 2024, resulted in benefits of 11.3% to the ETR for the year ended Dec. 31, 2024.
[4] | Plant regulatory differences primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit are offset by corresponding revenue reductions
[5] | Proceeds from tax credit transfers are included in cash received (paid) for income taxes in the consolidated statement of cash flows.
[6] | Prior periods have been reclassified to conform to current year presentation

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- Definition The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482685/740-10-50-3 + Details
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