Transactions With Affliated Parties (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction
Payment for commissions	$ 9	$ 9	$ 8
Earned premiums	7,958	7,225	6,478
Affiliated Parties
Related Party Transaction
Earned premiums	$ 51	$ 47	$ 47

Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-17(Column E))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480149/944-235-S99-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479655/944-605-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(13)(c))
-SubTopic 220
-Topic 942
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(1))
-SubTopic 220
-Topic 944
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Name:	us-gaap_PremiumsEarnedNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration