Guarantees and Commitments (Financing Commitments) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Guarantees and Product Warranties [Abstract]
Unused Commitments to Extend Credit	$ 6,142	$ 4,384
Commitments to provide capital to investees	778	504
Mortgage loan origination commitments	760	314
Home equity lines of credit commitments	187	226
Construction-lending commitments	$ 101	$ 127

Amount of financial support committed by investment company to investee that is contractually required.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 20
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=66023616&loc=SL35737432-115832

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