Fair Value (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Private equity investments carried at cost	$ 18	$ 8
Federal Reserve and Federal Home Loan Bank stock	102	109
Private equity investments accounted for under the equity method	$ 74	$ 61

Fair value portion of investments accounted under the equity method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=125513658&loc=d3e32014-111567

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant