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Stockholders' Equity - Narratives (Details) - USD ($) $ / shares in Units, $ in Thousands |  | 3 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 05, 2019 | Dec. 31, 2021 | Sep. 30, 2021 | Jun. 30, 2021 | Mar. 31, 2021 | Dec. 31, 2020 | Sep. 30, 2020 | Jun. 30, 2020 | Mar. 31, 2020 | Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Mar. 31, 2019 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Nov. 04, 2021 | May 31, 2021 | Jul. 31, 2019 | Dec. 31, 2018 | Apr. 26, 2018
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares, Issued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 38,097,525
Sale of Stock, Price Per Share | $ 13.125 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 15.00
Sale of Stock, Transaction Date | 11,175,927 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Decrease in percentage of shares outstanding (percent) | 7.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock Repurchase Program, Authorized Amount |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 150,000 |  | $ 100,000 |  |
Purchase of treasury shares |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 50,000 | $ 30,099 | $ 10,868 |  |  |  |  |
Stock Repurchase Program, Remaining Authorized Repurchase Amount |  | $ 159,000 |  |  |  |  |  |  |  |  |  |  |  | $ 159,000 |  |  |  |  |  |  |
Dividends paid (in dollars per share) |  | $ 0.01 | $ 0.01 | $ 0.01 | $ 0.01 | $ 0.01 | $ 0.01 | $ 0.01 | $ 0.085 | $ 0.085 | $ 0.085 | $ 0.085 | $ 0.085 | $ 0.04 | $ 0.115 | $ 0.34 |  |  |  |  |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Repurchase of Shares by Subsidiary | $ 250,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares, Issued |  | 263,255,708 |  |  |  | 267,188,547 |  |  |  | 270,485,308 |  |  |  | 263,255,708 | 267,188,547 | 270,485,308 |  |  |  | 290,537,612 |
Stock Repurchased and Retired During Period, Shares |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,658,544 | 3,328,574 | 1,004,685 |  |  |  |  |
Affiliated Entity | Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock Repurchased and Retired During Period, Shares | 19,047,619 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Brookfield [Member] | GrafTech International Ltd [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity Method Investment, Ownership Percentage |  | 24.30% |  |  |  | 55.30% |  |  |  |  |  |  |  | 24.30% | 55.30% |  |  | 24.00% |  |  |

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