Future Policy Benefit Reserves - Earned Premiums and Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Insurance [Abstract]
Earned premiums	$ 110	$ 115
Interest expense	$ 184	$ 190

Amount of gross premium income recognized for liability for future policy benefit.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 29E
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480046/944-40-55-29E

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480081/944-40-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480081/944-40-50-6

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