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Regulatory Matters - Summary of Utilities Rate Plans (RECO) (Details) - RECO - USD ($) $ in Millions | 1 Months Ended | 35 Months Ended
--- | --- | ---
Feb. 29, 2020 | Jan. 31, 2016 | Jan. 31, 2020
Electric |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Plan electric system storm hardening amount |  | $ 15.7 |
Plan period (years) |  | 3 years |
Scenario, Forecast |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Amortization to income of net regulatory (assets) and liabilities |  |  | $ 0.2
Regulatory liabilities, amortization period |  |  | 3 years
Amortization to income of net regulatory assets | $ 4.8 |  | $ 25.6
Regulatory assets, amortization period | 4 years |  | 4 years
Average rate base | $ 229.9 |  | $ 178.7
Weighted average cost of capital (after-tax) (percent) | 7.11% |  | 7.47%
Authorized return on common equity (percent) | 9.50% |  | 9.60%
Cost of long-term debt (percent) | 4.88% |  | 5.37%
Common equity ratio (percent) | 48.32% |  | 49.70%
Scenario, Forecast | Year 1 |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Base rate changes | $ 12.0 |  | $ 1.7
Actual return on common equity (percent) |  |  | 7.50%
Scenario, Forecast | Year 2 |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Actual return on common equity (percent) |  |  | 5.70%

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