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Stockholders' Equity (Details) - USD ($) $ in Thousands |  | 12 Months Ended |
--- | --- | --- | ---
May 03, 2024 | Dec. 31, 2024 | Dec. 31, 2023
Class of Stock [Line Items] |  |  |
Total capitalization |  | $ 2,612,233 | $ 2,267,065
OTP |  |  |
Class of Stock [Line Items] |  |  |
Equity to total capitalization ratio (as a percent) |  | 53.10% |
Net assets restricted from distribution |  | $ 834,500 |
Minimum | Minnesota Public Utilities Commission | OTP |  |  |
Class of Stock [Line Items] |  |  |
Public utilities, requested equity capital structure (as a percent) |  | 47.20% |
Maximum | OTP |  |  |
Class of Stock [Line Items] |  |  |
Total capitalization |  | $ 2,200,000 |
Maximum | Minnesota Public Utilities Commission | OTP |  |  |
Class of Stock [Line Items] |  |  |
Public utilities, requested equity capital structure (as a percent) |  | 57.70% |
Second Shelf Registration |  |  |
Class of Stock [Line Items] |  |  |
Shelf registration (in shares) | 1,500,000 |  |
Number of shares issued (in shares) |  | 70,469 |
Number of shares available for grant (in shares) |  | 1,429,531 |
Cumulative Preferred Shares |  |  |
Class of Stock [Line Items] |  |  |
Preferred stock, shares authorized (in shares) |  | 1,500,000 |
Preferred stock, shares outstanding (in shares) |  | 0 | 0
Cumulative Preference Shares |  |  |
Class of Stock [Line Items] |  |  |
Preferred stock, shares authorized (in shares) |  | 1,000,000 |
Preferred stock, shares outstanding (in shares) |  | 0 | 0

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