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v3.24.3

Summary of Significant Accounting Policies - Components of Gas and Electric Operating Revenue (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | $ 92.9 | $ 103.9 | $ 367.3 | $ 427.5
Billed and Unbilled Revenue |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 92.8 | 105.0 | 369.9 | 439.8
Rate Adjustment Mechanism Revenue |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 0.1 | (1.1) | (2.6) | (12.3)
Electric |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 62.5 | 72.1 | 192.5 | 244.8
Electric | Billed and Unbilled Revenue |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 67.5 | 80.6 | 197.3 | 248.1
Electric | Rate Adjustment Mechanism Revenue |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | (5.0) | (8.5) | (4.8) | (3.3)
Gas Segment |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 30.4 | 31.8 | 174.8 | 182.7
Gas Segment | Billed and Unbilled Revenue |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 25.3 | 24.4 | 172.6 | 191.7
Gas Segment | Rate Adjustment Mechanism Revenue |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 5.1 | 7.4 | 2.2 | (9.0)
Residential |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 46.3 | 55.9 | 176.7 | 222.9
Residential | Electric |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 37.4 | 47.5 | 108.4 | 147.5
Residential | Gas Segment |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 8.9 | 8.4 | 68.3 | 75.4
Commercial & Industrial |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 42.6 | 45.6 | 179.1 | 204.2
Commercial & Industrial | Electric |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 27.4 | 30.8 | 81.7 | 93.7
Commercial & Industrial | Gas Segment |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 15.2 | 14.8 | 97.4 | 110.5
Other |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 3.9 | 3.5 | 14.1 | 12.7
Other | Electric |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | 2.7 | 2.3 | 7.2 | 6.9
Other | Gas Segment |  |  |  |
Operating Revenues [Line Items] |  |  |  |
Total Gas and Electric Operating Revenues | $ 1.2 | $ 1.2 | $ 6.9 | $ 5.8

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