Investments - Gross realized gains and losses on available for sale fixed maturity security investment transactions (Details) - Fixed maturities - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Gross realized gains and losses on the sale of available for sale fixed maturity security investments
Gross gains	$ 3	$ 7	$ 12
Gross losses	$ (18)	$ (1)	$ (5)

Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27357-111563

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