Asbestos and environmental reinsurance retention.

No definition available.

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- Definition

Percentage of reserves for asbestos and environmental claims to total loss and loss expense reserves.

+ References

No definition available.

+ Details

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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

Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to asbestos and environmental claims, net of estimated reinsurance recoveries.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (cc)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

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- Definition

The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date.

+ References

+ 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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Property Casualty Loss And Loss Expenses (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property Casualty Insurance Underwriters
Certain accident, life and health loss reserves	$ 6,677,000,000	$ 6,088,000,000	$ 5,646,000,000	$ 5,219,000,000
Prior year claims and claims adjustments expense, (favorable) and unfavorable	(131,000,000)	(248,000,000)	(167,000,000)
Net loss and loss expense reserves for asbestos and environmental claims	$ 85,000,000	$ 85,000,000
Percentage of reserves for asbestos and environmental claims	2.00%	2.00%
Maximum
Property Casualty Insurance Underwriters
Reinsurance retention	$ 500,000
Life and Health Loss Reserves
Property Casualty Insurance Underwriters
Certain accident, life and health loss reserves	69,000,000	$ 59,000,000	61,000,000
Commercial Insurance
Property Casualty Insurance Underwriters
Prior year claims and claims adjustments expense, (favorable) and unfavorable	(95,000,000)	(192,000,000)	(157,000,000)
Commercial Insurance \| Commercial Casualty Line
Property Casualty Insurance Underwriters
Certain accident, life and health loss reserves	2,282,000,000
Prior year claims and claims adjustments expense, (favorable) and unfavorable	(54,000,000)	(78,000,000)	(47,000,000)
Commercial Insurance \| Workers' Compensation Line
Property Casualty Insurance Underwriters
Certain accident, life and health loss reserves	1,002,000,000
Prior year claims and claims adjustments expense, (favorable) and unfavorable	(39,000,000)	(77,000,000)	(58,000,000)
Commercial Insurance \| Commercial Property Line
Property Casualty Insurance Underwriters
Certain accident, life and health loss reserves	514,000,000
Prior year claims and claims adjustments expense, (favorable) and unfavorable	(16,000,000)	(25,000,000)	(47,000,000)
Commercial Insurance \| Commercial Auto Line
Property Casualty Insurance Underwriters
Certain accident, life and health loss reserves	685,000,000
Prior year claims and claims adjustments expense, (favorable) and unfavorable	17,000,000	(6,000,000)
Personal Insurance
Property Casualty Insurance Underwriters
Prior year claims and claims adjustments expense, (favorable) and unfavorable	(18,000,000)	(27,000,000)	13,000,000
Personal Insurance \| Personal Auto
Property Casualty Insurance Underwriters
Certain accident, life and health loss reserves	292,000,000
Prior year claims and claims adjustments expense, (favorable) and unfavorable	(15,000,000)	(26,000,000)
Personal Insurance \| Homeowner
Property Casualty Insurance Underwriters
Prior year claims and claims adjustments expense, (favorable) and unfavorable	(5,000,000)	11,000,000
Excess and Surplus Lines Insurance
Property Casualty Insurance Underwriters
Certain accident, life and health loss reserves	423,000,000
Prior year claims and claims adjustments expense, (favorable) and unfavorable	7,000,000	(11,000,000)	(24,000,000)
Reinsurance assumed and other non segment
Property Casualty Insurance Underwriters
Prior year claims and claims adjustments expense, (favorable) and unfavorable	$ (25,000,000)	$ (18,000,000)	$ 1,000,000