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Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($) $ in Millions | 6 Months Ended
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Jun. 30, 2022 | Jun. 30, 2021
Liability for Claims and Claims Adjustment Expense [Line Items] |  |
Net of loss reserve discounts | $ 15.0 | $ 10.0
Increase (decrease) in estimates for claims | 22.0 | (16.0)
Adjustment expense | 3.0 | 4.0
Liability recognized for best estimate net of reinsurance | 303.0 |
Liability recognized for best estimate net of reinsurance, reported losses | 292.0 |
Liability recognized for best estimate net of reinsurance, incurred but not reported (IBNR) | 11.0 |
Liability recognized for best estimate net of reinsurance, current accident year losses | 3.0 |
Insurance |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |
Liability recognized for best estimate net of reinsurance | 255.0 |
Liability recognized for best estimate net of reinsurance, current accident year losses | 1.0 |
Favorable reserve development net of premium offsets | 3.0 | 12.0
Reinsurance & Monoline Excess |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |
Liability recognized for best estimate net of reinsurance | 48.0 |
Liability recognized for best estimate net of reinsurance, current accident year losses | 2.0 |
Unfavorable reserve development net of premium offsets | $ 0.3 | $ 8.0

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437 + Details
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- Definition Current year monetary amount of the change in worker's compensation reserve liability resulting from the discount applied to reduce the reserve to present value. + References No definition available. + Details
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- Definition Liability for Claims and Claims Adjustment Expense, Net Of Reinsurance, Current Accident Year Losses + References No definition available. + Details
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- Definition Liability for Claims and Claims Adjustment Expense, Net Of Reinsurance, Incurred but Not Reported (IBNR) Claims, Amount + References No definition available. + Details
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- Definition Liability for Claims and Claims Adjustment Expense, Net Of Reinsurance, Reported Claims, Amount + References No definition available. + Details
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- Definition Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims Undiscounted Basis Prior Years, Increase (Decrease) + References No definition available. + Details
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