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Income Taxes (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Income Taxes [Line Items] |  |  |
Increase (Decrease) in Effective Tax Rate | (37.90%) | 30.20% |
Deferred Tax Assets, Operating Loss Carryforwards | $ 545.9 | $ 608.5 |
Deferred Tax Assets, Valuation Allowance | 7.8 | 6.4 |
Unrecognized Tax Benefits, Income Tax Penalties Expense | 0.0 | 0.0 | $ 0.0
Unrecognized Tax Benefits, Income Tax Penalties Accrued | 0.0 | $ 0.0 |
Massachusetts Business [Domain] |  |  |
Income Taxes [Line Items] |  |  |
Deferred Tax Assets, Valuation Allowance | 7.8 |  |
Internal Revenue Service (IRS) |  |  |
Income Taxes [Line Items] |  |  |
Deferred Tax Assets, Operating Loss Carryforwards | 464.4 |  |
State and Local Jurisdiction |  |  |
Income Taxes [Line Items] |  |  |
Deferred Tax Assets, Operating Loss Carryforwards | $ 73.7 |  |

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