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Summary of Significant Accounting Policies - Stock-Based Compensation (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Stock-based compensation expense | $ 8 | $ 7 | $ 8
Income tax benefits | $ 2 | $ 2 | $ 2
Restricted Stock [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Shares granted during the year | 82,433 | 76,806 | 115,746
Shares vested during the year | 75,107 | 75,007 | 44,829
Unvested shares at end of year | 158,464 | 152,140 | 157,860
Unrecognized compensation expense at end of year (in thousands) | $ 3 | $ 3 | $ 4
Total Shareholder Return Market-Based Awards [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Shares granted during the year | 45,739 | 34,912 | 69,814
Shares vested during the year | 64,640 | 61,456 | 43,730
Shares earned based on market metrics | 35,552 | 44,863 | 48,890
Unvested shares at end of year | 77,530 | 96,915 | 130,567
Unrecognized compensation expense at end of year (in thousands) | $ 2 | $ 2 | $ 4
Performance Shares [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Shares granted during the year | 137,161 | 104,685 | 69,814
Shares vested during the year | 64,640 | 61,456 | 43,730
Shares earned based on market metrics | 29,088 | 33,801 |
Unvested shares at end of year | 232,486 | 161,235 | 130,567
Unrecognized compensation expense at end of year (in thousands) | $ 3 | $ 2 | $ 2

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