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Common stock Common stock issuance (Details 2) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Class of Stock [Line Items] |  |  |
Common Stock, Shares Authorized | 500,000,000 | 500,000,000 |
Common Stock, Shares, Issued | 204,162,814 | 203,889,661 |
Proceeds from Issuance of Common Stock | $ (149,000) | $ 88,767,000 | $ 3,385,000
At-the-market offering |  |  |
Class of Stock [Line Items] |  |  |
Common Stock, Shares Authorized | 6,400,000 |  |
Common Stock, Shares, Issued | 0 | 2,800,000 |
Common Stock, Authorized Shares Remaining | 3,600,000 |  |
Proceeds from Issuance of Common Stock | $ (100,000) | $ 88,800,000 |
Payments of Stock Issuance Costs | $ 149,000 | $ 1,200,000 |
K-Plan |  |  |
Class of Stock [Line Items] |  |  |
Common Stock, Authorized Shares Remaining | 7,200,000 |  |

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