Regulatory Matters	6 Months Ended
Jun. 30, 2026
Regulated Operations [Abstract]
Regulatory Matters	REGULATORY MATTERS Regulation of the Corporation's utilities is generally consistent with that disclosed in Note 2 of the Corporation's annual audited consolidated financial statements ("2025 Annual Financial Statements"). A summary of significant outstanding regulatory matters follows. ITC Transmission Incentives: In 2021, the Federal Energy Regulatory Commission ("FERC") issued a supplemental notice of proposed rulemaking ("NOPR") on transmission incentives modifying the proposal in the initial NOPR released by FERC in 2020. The supplemental NOPR proposes to eliminate the 50-basis point regional transmission organization ("RTO") return on common equity ("ROE") incentive adder for RTO members that have been members for longer than three years. The timing and outcome of this proceeding are unknown. UNS Energy TEP General Rate Application: In June 2025, TEP filed a general rate application with the Arizona Corporation Commission ("ACC") requesting new rates effective September 1, 2026 using a December 31, 2024 test year, with post-test year adjustments through June 30, 2025. The application includes a proposal to phase-out or eliminate certain adjustor mechanisms, and requests an annual formulaic rate adjustment mechanism consistent with the ACC's approval of a formula rate policy statement in 2024. It also requests the deferral of certain costs associated with owning and operating Roadrunner Reserve II for future recovery. In June 2026, the Administrative Law Judge issued an extension of the procedural schedule such that a final decision on the rate case will be issued by November 17, 2026. The Residential Utility Consumer Office has challenged the ACC's authority to implement a formula rate framework through a policy statement, and in November 2025, the Arizona Court of Appeals ruled that the Residential Utility Consumer Office may proceed with its challenge. The timing and outcome of these regulatory and legal proceedings are unknown. The ACC has previously approved adjustor mechanisms, including formula-based mechanisms, in rate cases. UNS Gas General Rate Application: In February 2026, the ACC issued an order approving an allowed ROE of 9.61% and a 56% common equity component of capital structure. The order also approved an annual formulaic rate adjustment mechanism including a range of +/- 50 basis points around the allowed ROE and the inclusion of post-test year adjustments. New rates became effective March 1, 2026. FortisAlberta Third Performance-based Rate-setting ("PBR") Term Decision: In 2023, the Alberta Utilities Commission ("AUC") issued a decision establishing the parameters for the third PBR term for the period of 2024 through 2028. FortisAlberta sought permission to appeal the decision to the Court of Appeal of Alberta ("Court of Appeal") on the basis that the AUC erred in its decision to determine capital funding using 2018-2022 historical capital investments without consideration for funding of new capital programs included in the company's 2023 cost of service revenue requirement as approved by the AUC. In March 2025, the Court of Appeal granted FortisAlberta permission to appeal, which was heard in January 2026. A decision is expected in the third quarter of 2026. Depreciation Study: In May 2026, the AUC approved the negotiated settlement agreement that had been reached with respect to FortisAlberta's depreciation study. The corresponding reduction in FortisAlberta's depreciation rates has resulted in a true-up of $130 million. The settlement of the true-up will be addressed in a future rate application, with no impact to earnings anticipated as the related updates to revenue and depreciation expense are expected to be neutral.

Regulation of the Corporation's utilities is generally consistent with that disclosed in Note 2 of the Corporation's annual audited consolidated financial statements ("2025 Annual Financial Statements"). A summary of significant outstanding regulatory matters follows.

Transmission Incentives: In 2021, the Federal Energy Regulatory Commission ("FERC") issued a supplemental notice of proposed rulemaking ("NOPR") on transmission incentives modifying the proposal in the initial NOPR released by FERC in 2020. The supplemental NOPR proposes to eliminate the 50-basis point regional transmission organization ("RTO") return on common equity ("ROE") incentive adder for RTO members that have been members for longer than three years. The timing and outcome of this proceeding are unknown.

TEP General Rate Application: In June 2025, TEP filed a general rate application with the Arizona Corporation Commission ("ACC") requesting new rates effective September 1, 2026 using a December 31, 2024 test year, with post-test year adjustments through June 30, 2025. The application includes a proposal to phase-out or eliminate certain adjustor mechanisms, and requests an annual formulaic rate adjustment mechanism consistent with the ACC's approval of a formula rate policy statement in 2024. It also requests the deferral of certain costs associated with owning and operating Roadrunner Reserve II for future recovery. In June 2026, the Administrative Law Judge issued an extension of the procedural schedule such that a final decision on the rate case will be issued by November 17, 2026.

The Residential Utility Consumer Office has challenged the ACC's authority to implement a formula rate framework through a policy statement, and in November 2025, the Arizona Court of Appeals ruled that the Residential Utility Consumer Office may proceed with its challenge. The timing and outcome of these regulatory and legal proceedings are unknown. The ACC has previously approved adjustor mechanisms, including formula-based mechanisms, in rate cases.

UNS Gas General Rate Application: In February 2026, the ACC issued an order approving an allowed ROE of 9.61% and a 56% common equity component of capital structure. The order also approved an annual formulaic rate adjustment mechanism including a range of +/- 50 basis points around the allowed ROE and the inclusion of post-test year adjustments. New rates became effective March 1, 2026.

Third Performance-based Rate-setting ("PBR") Term Decision: In 2023, the Alberta Utilities Commission ("AUC") issued a decision establishing the parameters for the third PBR term for the period of 2024 through 2028. FortisAlberta sought permission to appeal the decision to the Court of Appeal of Alberta ("Court of Appeal") on the basis that the AUC erred in its decision to determine capital funding using 2018-2022 historical capital investments without consideration for funding of new capital programs included in the company's 2023 cost of service revenue requirement as approved by the AUC. In March 2025, the Court of Appeal granted FortisAlberta permission to appeal, which was heard in January 2026. A decision is expected in the third quarter of 2026.