Derivative Instruments - Summary of Gross Principal Notional Outstanding for CDS Contracts (Detail) - Variable Interest Entity [Member] - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Interest Rate Swap [Member]
Ambac Rating
Derivative, Notional Amount	$ 1,662	$ 1,573
Interest Rate Swap One [Member]
Ambac Rating
Derivative, Notional Amount	864	887
Currency Swaps [Member]
Ambac Rating
Derivative, Notional Amount	$ 149	$ 176

Nominal or face amount used to calculate payment on derivative.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant