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Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Compensation expense related to stock incentive plans | $ 4 | $ 5 | $ 11 | $ 15
Stock Incentive Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Restricted Common Stock, shares issued (shares) |  |  | 207,020 |
Restricted Common Stock, fair value per share (USD per share) |  |  | $ 111.13 |

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