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Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Thousands | Jun. 30, 2026 | Dec. 31, 2025
--- | --- | ---
Detail of regulatory liabilities |  |
Total regulatory liabilities | $ 1,977,868 | $ 1,947,030
Less: current regulatory liabilities | 194,643 | 210,909
Total non-current regulatory liabilities | 1,783,225 | 1,736,121
AROs and removal costs |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 298,964 | 286,907
Other postretirement benefits |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 226,529 | 233,952
Four Corners coal reclamation |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 97,048 | 97,988
Income taxes — deferred investment tax credit |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 80,553 | 81,949
Deferred fuel and purchased power |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 61,437 | 0
Income taxes — change in state rates |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 55,201 | 56,260
RES |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 56,847 | 54,551
Sundance maintenance |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 25,969 | 25,668
Spent nuclear fuel |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 16,928 | 20,492
DSM |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 12,498 | 26,228
TCA Balancing Account |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 10,654 | 4,860
TEAM |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 3,436 | 3,738
Deferred fuel and purchased power — mark-to-market (Note 10) |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 0 | 3,641
Other |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 1,977 | 3,063
ACC | Excess deferred income taxes - Tax Cuts and Jobs Act |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | 832,335 | 847,572
FERC | Excess deferred income taxes - Tax Cuts and Jobs Act |  |
Detail of regulatory liabilities |  |
Total regulatory liabilities | $ 197,492 | $ 200,161

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