Investment Securities - Amortized Cost and Estimated Fair Value of Securities by Contractual Maturity (Details) $ in Millions	Mar. 31, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items]
Due within one year	$ 136
Due from one to five years	926
Due from five to ten years	1,839
Due after ten years	4,698
Debt securities, available-for-sale, amortized cost, total	7,599
Agency - commercial
Debt Securities, Available-for-sale [Line Items]
Due within one year	21
Due from one to five years	175
Due from five to ten years	328
Due after ten years	4,609
Debt securities, available-for-sale, amortized cost, total	5,133
U.S. Treasury and Government Agencies
Debt Securities, Available-for-sale [Line Items]
Due within one year	97
Due from one to five years	300
Due from five to ten years	1,377
Due after ten years	125
Debt securities, available-for-sale, amortized cost, total	1,899
US States and Political Subdivisions Debt Securities
Debt Securities, Available-for-sale [Line Items]
Due within one year	0
Due from one to five years	0
Due from five to ten years	18
Due after ten years	0
Debt securities, available-for-sale, amortized cost, total	18
Other Debt Obligations
Debt Securities, Available-for-sale [Line Items]
Due within one year	20
Due from one to five years	459
Due from five to ten years	469
Due after ten years	378
Debt securities, available-for-sale, amortized cost, total	$ 1,326

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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