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Accounting Policies (Tables) | 12 Months Ended
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Dec. 31, 2020
Accounting Policies [Abstract] |
Disposal Groups, Pretax Income (Loss) | The Massachusetts Business had the following pretax income (loss) for the twelve months ended December 31, 2020, 2019 and 2018:
|  | Twelve Months Ended December 31,
(in millions) |  | 2020 |  | 2019 |  | 2018 |
Pretax Income (Loss) |  | ($422.3) |  | $36.8 |  | ($835.6) |

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