LOANS - Types of Consumer Loan Modifications and Their Financial Effect (Details) - Consumer $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)
In North America offices
Financing Receivable, Impaired [Line Items]
Modifications as % of loans	0.12%
Total modifications balance	$ 338
In North America offices | Interest rate reduction
Financing Receivable, Impaired [Line Items]
Total modifications balance	276
In North America offices | Term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	15
In North America offices | Payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	37
In North America offices | Combination: interest rate reduction and term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	10
In North America offices | Combination: term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
In North America offices | Combination: interest rate reduction, term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 0
In offices outside North America
Financing Receivable, Impaired [Line Items]
Modifications as % of loans	0.36%
Total modifications balance	$ 279
In offices outside North America | Interest rate reduction
Financing Receivable, Impaired [Line Items]
Total modifications balance	13
In offices outside North America | Term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	2
In offices outside North America | Payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	17
In offices outside North America | Combination: interest rate reduction and term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	4
In offices outside North America | Combination: term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	242
In offices outside North America | Combination: interest rate reduction, term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 1
Residential mortgages | In North America offices
Financing Receivable, Impaired [Line Items]
Trial modifications, period	3 months
Trial modifications, amount	$ 25
Loans that had gone through bankruptcy	$ 1
Modifications as % of loans	0.05%
Total modifications balance	$ 52
Weighted average interest rate reduction %	2.00%
Weighted average term extension	183 months
Weighted average delay in payments	6 months
Residential mortgages | In North America offices | Interest rate reduction
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 0
Residential mortgages | In North America offices | Term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	15
Residential mortgages | In North America offices | Payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	34
Residential mortgages | In North America offices | Combination: interest rate reduction and term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	3
Residential mortgages | In North America offices | Combination: term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Residential mortgages | In North America offices | Combination: interest rate reduction, term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 0
Residential mortgages | In offices outside North America
Financing Receivable, Impaired [Line Items]
Modifications as % of loans	0.97%
Total modifications balance	$ 260
Weighted average interest rate reduction %	0.00%
Weighted average term extension	1 month
Weighted average delay in payments	1 month
Payment deferral period	4 months
Residential mortgages | In offices outside North America | Interest rate reduction
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 0
Residential mortgages | In offices outside North America | Term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Residential mortgages | In offices outside North America | Payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	17
Residential mortgages | In offices outside North America | Combination: interest rate reduction and term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Residential mortgages | In offices outside North America | Combination: term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	242
Residential mortgages | In offices outside North America | Combination: interest rate reduction, term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 1
Home equity loans | In North America offices
Financing Receivable, Impaired [Line Items]
Modifications as % of loans	0.19%
Total modifications balance	$ 8
Weighted average interest rate reduction %	3.00%
Weighted average term extension	120 months
Weighted average delay in payments	5 months
Home equity loans | In North America offices | Interest rate reduction
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 0
Home equity loans | In North America offices | Term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Home equity loans | In North America offices | Payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	3
Home equity loans | In North America offices | Combination: interest rate reduction and term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	5
Home equity loans | In North America offices | Combination: term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Home equity loans | In North America offices | Combination: interest rate reduction, term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Credit cards
Financing Receivable, Impaired [Line Items]
Loans forgiven	$ 9
Credit cards | In North America offices
Financing Receivable, Impaired [Line Items]
Modifications as % of loans	0.19%
Total modifications balance	$ 276
Weighted average interest rate reduction %	22.00%
Credit cards | In North America offices | Interest rate reduction
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 276
Credit cards | In North America offices | Term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Credit cards | In North America offices | Payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Credit cards | In North America offices | Combination: interest rate reduction and term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Credit cards | In North America offices | Combination: term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Credit cards | In North America offices | Combination: interest rate reduction, term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 0
Credit cards | In offices outside North America
Financing Receivable, Impaired [Line Items]
Modifications as % of loans	0.09%
Total modifications balance	$ 12
Weighted average interest rate reduction %	18.00%
Credit cards | In offices outside North America | Interest rate reduction
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 12
Credit cards | In offices outside North America | Term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Credit cards | In offices outside North America | Payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Credit cards | In offices outside North America | Combination: interest rate reduction and term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Credit cards | In offices outside North America | Combination: term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Credit cards | In offices outside North America | Combination: interest rate reduction, term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Personal, small business and other
Financing Receivable, Impaired [Line Items]
Loans forgiven	$ 1
Personal, small business and other | In North America offices
Financing Receivable, Impaired [Line Items]
Modifications as % of loans	0.01%
Total modifications balance	$ 2
Weighted average interest rate reduction %	7.00%
Weighted average term extension	16 months
Personal, small business and other | In North America offices | Interest rate reduction
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 0
Personal, small business and other | In North America offices | Term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Personal, small business and other | In North America offices | Payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Personal, small business and other | In North America offices | Combination: interest rate reduction and term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	2
Personal, small business and other | In North America offices | Combination: term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Personal, small business and other | In North America offices | Combination: interest rate reduction, term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 0
Personal, small business and other | In offices outside North America
Financing Receivable, Impaired [Line Items]
Modifications as % of loans	0.02%
Total modifications balance	$ 7
Weighted average interest rate reduction %	6.00%
Weighted average term extension	20 months
Weighted average delay in payments	6 months
Personal, small business and other | In offices outside North America | Interest rate reduction
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 1
Personal, small business and other | In offices outside North America | Term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	2
Personal, small business and other | In offices outside North America | Payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Personal, small business and other | In offices outside North America | Combination: interest rate reduction and term extension
Financing Receivable, Impaired [Line Items]
Total modifications balance	4
Personal, small business and other | In offices outside North America | Combination: term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	0
Personal, small business and other | In offices outside North America | Combination: interest rate reduction, term extension and payment delay
Financing Receivable, Impaired [Line Items]
Total modifications balance	$ 0