Summary of Significant Accounting Policies - Insurance-related Assessments (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Insurance-related Assessments [Abstract]
Liability balance for guaranty fund	$ 89	$ 86

This item represents a non-contingent liability for the fair value of an obligation to stand ready to perform over the term of a guaranty issued in the event that specified triggering events or conditions occur.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(15))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 460
-SubTopic 10
-Name Accounting Standards Codification
-Section 25
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482050/460-10-25-4

Name:	us-gaap_GuarantyLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant