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Reserves for Loss and Loss Expenses (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2022 | Mar. 31, 2021
Liability for Claims and Claims Adjustment Expense [Line Items] |  |
Net of loss reserve discounts | $ 7 | $ 5
Increase (decrease) in estimates for claims | 4 | (5)
Adjustment expense | 1 | 3
Liability recognized for best estimate net of reinsurance | 290 |
Liability recognized for best estimate net of reinsurance, reported losses | 268 |
Liability recognized for best estimate net of reinsurance, incurred but not reported (IBNR) | 22 |
Liability recognized for best estimate net of reinsurance, current accident year losses | 1 |
Insurance |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |
Liability recognized for best estimate net of reinsurance | 246 |
Favorable reserve development net of premium offsets | 6 | 6
Reinsurance & Monoline Excess |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |
Liability recognized for best estimate net of reinsurance | 44 |
Unfavorable reserve development net of premium offsets | $ 5 | $ 3

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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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- Definition Liability for Claims and Claims Adjustment Expense, Net Of Reinsurance + References No definition available. + Details
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- Definition Unfavorable Reserve Development Net Of Premium Offsets + References No definition available. + Details
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