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Stockholders' Equity (Details) - USD ($) $ in Thousands |  | 12 Months Ended |
--- | --- | --- | ---
May 03, 2021 | Dec. 31, 2022 | Dec. 31, 2021
Class of Stock [Line Items] |  |  |
Total capitalization |  | $ 2,041,138 | $ 1,724,791
OTP |  |  |
Class of Stock [Line Items] |  |  |
Equity to total capitalization (as a percent) |  | 54.70% |
Net assets restricted from distribution |  | $ 737,400 |
Minimum | Minnesota Public Utilities Commission | OTP |  |  |
Class of Stock [Line Items] |  |  |
Public utilities, requested equity capital structure (as a percent) |  | 47.50% |
Maximum | OTP |  |  |
Class of Stock [Line Items] |  |  |
Total capitalization |  | $ 1,800,000 |
Maximum | Minnesota Public Utilities Commission | OTP |  |  |
Class of Stock [Line Items] |  |  |
Public utilities, requested equity capital structure (as a percent) |  | 58.00% |
Second Shelf Registration |  |  |
Class of Stock [Line Items] |  |  |
Shelf registration (in shares) | 1,500,000 |  |
Number of shares issued (in shares) |  | 133,827 |
Number of shares available for grant (in shares) |  | 1,250,993 |
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 |

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