| Document and Entity Information | 12 Months Ended |
| Dec. 31, 2022 | |
| Cover [Abstract] | |
| Document Type | DEF 14A |
| Entity Registrant Name | Kaiser Aluminum Corporation |
| Amendment Flag | false |
| Entity Central Index Key | 0000811596 |
| Pay vs Performance Disclosure - USD ($) | 5 Months Ended | 7 Months Ended | 12 Months Ended | ||
| Dec. 31, 2020 | Jul. 30, 2020 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | |
| Pay vs Performance Disclosure [Table] | |||||
| Pay vs Performance [Table Text Block] | As required by Section 953(a) of the Dodd-Frank Wall Street Reform and Consumer Protection Act, and Item 402(v) of Regulation S-K, we are providing the following information about the relationship between executive “compensation actually paid” to our principal executive officers (“PEO”) and to our non-PEO named executive officers and certain financial performance of the Company. Year Summary Compensation Table (SCT) Total for PEO 1 (1) Compensation actually paid to PEO 1 (1)(2)(3) SCT Total for PEO 2 (1) Compensation actually paid to PEO 2 (1)(2)(4) Average SCT Total for non-PEO NEOs (1) Average compensation actually paid to non-PEO NEOs (1)(2)(5) Value of Initial Fixed $100 Investment based on: Net Income (Loss) Adjusted EBITDA ($ millions) (8) TSR Peer Group TSR (6) (a) (b) (c) (b) (c) (d) (e) (f) (g) (h) (i) 2022 $ 5,123,725 $ 1,614,307 N/A N/A $ 1,465,483 $ 639,781 $ 75.68 $ 136.42 $ ( 30 ) $ 142 2021 $ 5,505,512 $ 2,519,794 N/A N/A $ 2,052,660 $ 1,363,746 $ 90.25 $ 145.27 $ ( 19 ) $ 185 2020 $ 3,231,260 $ 2,110,286 $ 4,249,853 $ 2,119,022 $ 1,727,323 $ 1,705,476 $ 92.45 $ 122.68 $ 29 $ 154 ______________ (1) For 2022, the PEO is Mr. Harvey ("PEO1") and the non-PEO named executive officers are Messrs. Donnan, West, Walsh and Tiffany. For 2021, the PEO is Mr. Harvey and the non-PEO named executive officers are Messrs. Donnan, West, Walsh and Parkinson. For 2020, the PEOs are Messrs. Harvey and Hockema and the non-PEO named executive officers are Messrs. Donnan, West, Walsh and Tiffany. Mr. Hockema served as our PEO ("PEO2") until July 30, 2020 and Mr. Harvey has served as our PEO since July 31, 2020. (2) The fair value of equity awards reported for the purposes of compensation actually paid is calculated using the same methodologies as the fair value of equity awards reported in the Summary Compensation Table and adjusted for the share price and, for performance share awards, the probable outcome of the performance conditions, including as applicable as of December 31 st of each applicable year. (3) The table below sets forth the values deducted and added to the Summary Compensation Table Total for PEO 1. Year Summary Compensation Table Total for PEO 1 Exclusion of Change in Pension Value for PEO 1 Exclusion of Stock Awards Inclusion of Equity Values Compensation Actually Paid to PEO 1 2022 $ 5,123,725 $ 4,854 $ 3,414,128 $ ( 90,436 ) $ 1,614,307 2021 $ 5,505,512 $ 5,248 $ 3,697,874 $ 717,404 $ 2,519,794 2020 $ 3,231,260 $ 81,095 $ 1,769,707 $ 729,827 $ 2,110,286 The amounts in the Inclusion of Equity Values in the tables above are derived from the amounts set forth in the following tables: Year End Fair Value of Equity Awards Granted During Year That Remained Unvested as Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for PEO 1 Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for PEO 1 Total Inclusion of Equity Values for PEO 1 2022 $ 1,755,073 $ ( 1,309,747 ) $ ( 535,762 ) $ ( 90,436 ) 2021 $ 1,950,797 $ ( 1,355,240 ) $ 121,847 $ 717,404 2020 $ 1,906,561 $ ( 854,216 ) $ ( 322,518 ) $ 729,827 (4) The table below sets forth the values deducted and added to the Summary Compensation Table Total for PEO 2. Year Summary Compensation Table Total for PEO 2 Exclusion of Change in Pension Value for PEO 2 Exclusion of Stock Awards Inclusion of Equity Values Compensation Actually Paid to PEO 2 2020 $ 4,249,853 $ 6,210 $ 2,997,420 $ 872,799 $ 2,119,022 The amounts in the Inclusion of Equity Values in the tables above are derived from the amounts set forth in the following tables: Year Year-End Fair Value of Equity Awards Granted During Year That Remained Unvested as Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for PEO 2 Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for PEO 2 Total Inclusion of Equity Values for PEO 2 2020 $ 2,579,395 $ ( 1,084,565 ) $ ( 622,031 ) $ 872,799 (5) The table below sets forth the values deducted and added to the average Summary Compensation Table Total for non-PEO named executive officers. Year Average Summary Compensation Table Total for non-PEO NEOs Average Exclusion of Change in Pension Value for Non-PEO NEOs Exclusion of Stock Awards Inclusion of Equity Values Average Compensation Actually Paid to non-PEO NEOs 2022 $ 1,465,483 $ 0 $ 666,175 $ ( 159,527 ) $ 639,781 2021 $ 2,052,660 $ 3,214 $ 1,277,523 $ 591,823 $ 1,363,746 2020 $ 1,727,323 $ 17,874 $ 1,053,167 $ 1,049,194 $ 1,705,476 The amounts in the Inclusion of Equity Values in the tables above are derived from the amounts set forth in the following tables: Year Average Year-End Fair Value of Average Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for Non-PEO NEOs Average Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for Non-PEO NEOs Total Average Inclusion of Equity Values for Non-PEO NEOs 2022 $ 375,684 $ ( 540,385 ) $ 5,174 $ ( 159,527 ) 2021 $ 865,328 $ ( 302,341 ) $ 28,836 $ 591,823 2020 $ 1,297,037 $ ( 171,015 ) $ ( 76,828 ) $ 1,049,194 (6) The table below sets forth the values deducted and added to the average Summary Compensation Table Total for non-PEO named executive officers. (7) Net income (loss) is calculated in accordance with GAAP. (8) Our company-selected measure is Adjusted EBITDA (as defined in Exhibit A), which is used as the key performance metric in our short-term incentive plans. | ||||
| Company Selected Measure Name | Adjusted EBITDA | ||||
| Named Executive Officers, Footnote [Text Block] | (1) For 2022, the PEO is Mr. Harvey ("PEO1") and the non-PEO named executive officers are Messrs. Donnan, West, Walsh and Tiffany. For 2021, the PEO is Mr. Harvey and the non-PEO named executive officers are Messrs. Donnan, West, Walsh and Parkinson. For 2020, the PEOs are Messrs. Harvey and Hockema and the non-PEO named executive officers are Messrs. Donnan, West, Walsh and Tiffany. Mr. Hockema served as our PEO ("PEO2") until July 30, 2020 and Mr. Harvey has served as our PEO since July 31, 2020. | ||||
| Adjustment To PEO Compensation, Footnote [Text Block] | (3) The table below sets forth the values deducted and added to the Summary Compensation Table Total for PEO 1. Year Summary Compensation Table Total for PEO 1 Exclusion of Change in Pension Value for PEO 1 Exclusion of Stock Awards Inclusion of Equity Values Compensation Actually Paid to PEO 1 2022 $ 5,123,725 $ 4,854 $ 3,414,128 $ ( 90,436 ) $ 1,614,307 2021 $ 5,505,512 $ 5,248 $ 3,697,874 $ 717,404 $ 2,519,794 2020 $ 3,231,260 $ 81,095 $ 1,769,707 $ 729,827 $ 2,110,286 (4) The table below sets forth the values deducted and added to the Summary Compensation Table Total for PEO 2. Year Summary Compensation Table Total for PEO 2 Exclusion of Change in Pension Value for PEO 2 Exclusion of Stock Awards Inclusion of Equity Values Compensation Actually Paid to PEO 2 2020 $ 4,249,853 $ 6,210 $ 2,997,420 $ 872,799 $ 2,119,022 | ||||
| Non-PEO NEO Average Total Compensation Amount | $ 1,465,483 | $ 2,052,660 | $ 1,727,323 | ||
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 639,781 | 1,363,746 | 1,705,476 | ||
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | (5) The table below sets forth the values deducted and added to the average Summary Compensation Table Total for non-PEO named executive officers. Year Average Summary Compensation Table Total for non-PEO NEOs Average Exclusion of Change in Pension Value for Non-PEO NEOs Exclusion of Stock Awards Inclusion of Equity Values Average Compensation Actually Paid to non-PEO NEOs 2022 $ 1,465,483 $ 0 $ 666,175 $ ( 159,527 ) $ 639,781 2021 $ 2,052,660 $ 3,214 $ 1,277,523 $ 591,823 $ 1,363,746 2020 $ 1,727,323 $ 17,874 $ 1,053,167 $ 1,049,194 $ 1,705,476 | ||||
| Equity Valuation Assumption Difference, Footnote [Text Block] | The amounts in the Inclusion of Equity Values in the tables above are derived from the amounts set forth in the following tables: Year End Fair Value of Equity Awards Granted During Year That Remained Unvested as Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for PEO 1 Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for PEO 1 Total Inclusion of Equity Values for PEO 1 2022 $ 1,755,073 $ ( 1,309,747 ) $ ( 535,762 ) $ ( 90,436 ) 2021 $ 1,950,797 $ ( 1,355,240 ) $ 121,847 $ 717,404 2020 $ 1,906,561 $ ( 854,216 ) $ ( 322,518 ) $ 729,827 The amounts in the Inclusion of Equity Values in the tables above are derived from the amounts set forth in the following tables: Year Year-End Fair Value of Equity Awards Granted During Year That Remained Unvested as Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for PEO 2 Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for PEO 2 Total Inclusion of Equity Values for PEO 2 2020 $ 2,579,395 $ ( 1,084,565 ) $ ( 622,031 ) $ 872,799 The amounts in the Inclusion of Equity Values in the tables above are derived from the amounts set forth in the following tables: Year Average Year-End Fair Value of Average Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards for Non-PEO NEOs Average Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year for Non-PEO NEOs Total Average Inclusion of Equity Values for Non-PEO NEOs 2022 $ 375,684 $ ( 540,385 ) $ 5,174 $ ( 159,527 ) 2021 $ 865,328 $ ( 302,341 ) $ 28,836 $ 591,823 2020 $ 1,297,037 $ ( 171,015 ) $ ( 76,828 ) $ 1,049,194 | ||||
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | Compensation Actually Paid versus TSR The table below describes the relationship between compensation actually paid to our PEO and the average of the compensation actually paid to our non-PEO NEOs our cumulative TSR for fiscal years 2020 to 2022. The table shows that compensation actually paid to our executive officers is generally directionally aligned with changes in our cumulative total shareholder return for the time period reported. The table above also describes the relationship between our one-, two- and three-year cumulative TSR compared to the weighted average one-, two- and three-year cumulative TSR of the companies in the S&P 600 SmallCap Materials Index. As previously discussed, our TSR over the last three years was impacted by a series of external issues and challenges initiating with the onset of the COVID-19 pandemic late in the first quarter of 2020 that negatively impacted the end markets for many of our products, including large commercial aerospace applications. In addition, while the S&P 600 SmallCap Materials Index reflects our industry sector, many of the companies included in the index were not as heavily impacted by the COVID-19 pandemic related impact on the aerospace industry. | ||||
| Compensation Actually Paid vs. Net Income [Text Block] | C ompensation Actually Paid versus Net Income The table below describes the relationship between the compensation actually paid to our PEOs and the average of the compensation actually paid to our non-PEO named executive officers and our Net Income for fiscal years 2020 to 2022. We do not use net income as a metric in our incentive compensation plans and programs. Therefore, compensation actually paid to our named executive officers will not necessarily be as heavily influenced by changes in our net income. Nonetheless, the table shows that compensation actually paid to our named executive officers is generally directionally aligned with changes in our Net Income for the time period reported. | ||||
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | Compensation Actually Paid versus Adjusted EBITDA The table below describes the relationship between compensation actually paid to our PEOs and the average of the compensation actually paid to our non-PEO named executive officers and our Adjusted EBITDA for fiscal years 2020 through 2022. The table shows that the compensation actually paid to our named executive officers is generally directionally aligned with changes in our adjusted EBITDA for the time period reported after taking into account Warrick related increases in our adjusted EBITDA in 2021, Warrick related increases in the adjusted EBITDA based performance targets in 2021 and 2022 and challenges faced in 2022 and described in more detail in our CD&A. | ||||
| Tabular List [Table Text Block] | The following are the most important financial performance measures used by the Company to link executive compensation actually paid to our NEOs to the Company’s performance for the most recently completed fiscal year. Most Important Performance Measures • Adjusted EBITDA • Relative TSR • Adjusted EBITDA Margin | ||||
| Total Shareholder Return Amount | $ 75.68 | 90.25 | 92.45 | ||
| Peer Group Total Shareholder Return Amount | 136.42 | 145.27 | 122.68 | ||
| Net Income (Loss) | $ (30,000,000) | $ (19,000,000) | $ 29,000,000 | ||
| Company Selected Measure Amount | 142,000,000 | 185,000,000 | 154,000,000 | ||
| PEO Name | Mr. Harvey | Mr. Hockema | Mr. Harvey | Mr. Harvey | |
| Measure [Axis]: 1 | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Measure Name | Adjusted EBITDA | ||||
| Non-GAAP Measure Description [Text Block] | (8) Our company-selected measure is Adjusted EBITDA (as defined in Exhibit A), which is used as the key performance metric in our short-term incentive plans. | ||||
| Measure [Axis]: 2 | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Measure Name | Relative TSR | ||||
| Measure [Axis]: 3 | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Measure Name | Adjusted EBITDA Margin | ||||
| PEO 1 [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| PEO Total Compensation Amount | $ 5,123,725 | $ 5,505,512 | $ 3,231,260 | ||
| PEO Actually Paid Compensation Amount | 1,614,307 | 2,519,794 | 2,110,286 | ||
| PEO 2 [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| PEO Total Compensation Amount | 4,249,853 | ||||
| PEO Actually Paid Compensation Amount | 2,119,022 | ||||
| PEO [Member] | PEO 1 [Member] | Exclusion of Change in Pension Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 4,854 | 5,248 | 81,095 | ||
| PEO [Member] | PEO 1 [Member] | Exclusion of Stock Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 3,414,128 | 3,697,874 | 1,769,707 | ||
| PEO [Member] | PEO 1 [Member] | Inclusion of Equity Values [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (90,436) | 717,404 | 729,827 | ||
| PEO [Member] | PEO 1 [Member] | Inclusion of Equity Values Includes End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 1,755,073 | 1,950,797 | 1,906,561 | ||
| PEO [Member] | PEO 1 [Member] | Inclusion of Equity Values Includes Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (1,309,747) | (1,355,240) | (854,216) | ||
| PEO [Member] | PEO 1 [Member] | Inclusion of Equity Values Includes Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (535,762) | 121,847 | (322,518) | ||
| PEO [Member] | PEO 2 [Member] | Exclusion of Change in Pension Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 6,210 | ||||
| PEO [Member] | PEO 2 [Member] | Exclusion of Stock Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 2,997,420 | ||||
| PEO [Member] | PEO 2 [Member] | Inclusion of Equity Values [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 872,799 | ||||
| PEO [Member] | PEO 2 [Member] | Inclusion of Equity Values Includes Year-End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 2,579,395 | ||||
| PEO [Member] | PEO 2 [Member] | Inclusion of Equity Values Includes Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (1,084,565) | ||||
| PEO [Member] | PEO 2 [Member] | Inclusion of Equity Values Includes Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (622,031) | ||||
| Non-PEO NEO [Member] | Exclusion of Change in Pension Value [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 0 | 3,214 | 17,874 | ||
| Non-PEO NEO [Member] | Exclusion of Stock Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 666,175 | 1,277,523 | 1,053,167 | ||
| Non-PEO NEO [Member] | Inclusion of Equity Values [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (159,527) | 591,823 | 1,049,194 | ||
| Non-PEO NEO [Member] | Inclusion of Equity Values Includes Year-End Fair Value of Equity Awards Granted During Year That Remained Unvested as of Last Day of Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | 375,684 | 865,328 | 1,297,037 | ||
| Non-PEO NEO [Member] | Inclusion of Equity Values Includes Change in Fair Value from Last Day of Prior Year to Last Day of Year of Unvested Equity Awards [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | (540,385) | (302,341) | (171,015) | ||
| Non-PEO NEO [Member] | Inclusion of Equity Values Includes Change in Fair Value from Last Day of Prior Year to Vesting Date of Unvested Equity Awards that Vested During Year [Member] | |||||
| Pay vs Performance Disclosure [Table] | |||||
| Adjustment to Compensation Amount | $ 5,174 | $ 28,836 | $ (76,828) | ||
