Fair Value Option - Loans and Lending Commitments (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Aggregate contractual principal amount of performing loans and long-term receivables in excess of fair value	$ 1,430	$ 958
Loans on nonaccrual status and/or more than 90 days past due Aggregate contractual principal in excess of fair value	10,279	10,526
Aggregate fair value	$ 3,315	$ 3,519

No definition available.

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- Definition

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of loans and long-term receivables (other than securities categorized as trading, available-for-sale or held-to-maturity) that have contractual principal amounts and for which the fair value option has been elected.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=123596393&loc=d3e14064-108612

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

This item represents the aggregate fair value of loans held as assets that are in nonaccrual status for which the fair value option has been elected, if the entity's policy is to recognize interest income separately from other changes in fair value.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (e)(2)
-URI http://asc.fasb.org/extlink&oid=123596393&loc=d3e14064-108612

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

For loans held as assets for which the fair value option has been elected, this item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of those loans that are 90 days or more past due, in nonaccrual status, or both.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (e)(3)
-URI http://asc.fasb.org/extlink&oid=123596393&loc=d3e14064-108612

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant