LOANS - Performance of Modified Consumer Loans (Details) - Consumer $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($)
In North America offices
Financing Receivable, Modified [Line Items]
Total modified loans balance	$ 339
Gross credit losses	13
In North America offices | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	155
In North America offices | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	100
In North America offices | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	84
In offices outside North America
Financing Receivable, Modified [Line Items]
Total modified loans balance	278
Gross credit losses	1
In offices outside North America | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	277
In offices outside North America | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	1
In offices outside North America | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Residential mortgages | In North America offices
Financing Receivable, Modified [Line Items]
Total modified loans balance	52
Gross credit losses	0
Residential mortgages | In North America offices | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	18
Residential mortgages | In North America offices | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	18
Residential mortgages | In North America offices | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	16
Residential mortgages | In offices outside North America
Financing Receivable, Modified [Line Items]
Total modified loans balance	260
Gross credit losses	1
Residential mortgages | In offices outside North America | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	259
Residential mortgages | In offices outside North America | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	1
Residential mortgages | In offices outside North America | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Home equity loans | In North America offices
Financing Receivable, Modified [Line Items]
Total modified loans balance	9
Gross credit losses	0
Home equity loans | In North America offices | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	6
Home equity loans | In North America offices | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	1
Home equity loans | In North America offices | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	2
Credit cards | In North America offices
Financing Receivable, Modified [Line Items]
Total modified loans balance	276
Gross credit losses	13
Credit cards | In North America offices | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	129
Credit cards | In North America offices | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	81
Credit cards | In North America offices | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	66
Credit cards | In offices outside North America
Financing Receivable, Modified [Line Items]
Total modified loans balance	12
Gross credit losses	0
Credit cards | In offices outside North America | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	12
Credit cards | In offices outside North America | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Credit cards | In offices outside North America | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Personal, small business and other | In North America offices
Financing Receivable, Modified [Line Items]
Total modified loans balance	2
Gross credit losses	0
Personal, small business and other | In North America offices | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	2
Personal, small business and other | In North America offices | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Personal, small business and other | In North America offices | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Personal, small business and other | In offices outside North America
Financing Receivable, Modified [Line Items]
Total modified loans balance	6
Gross credit losses	0
Personal, small business and other | In offices outside North America | Current
Financing Receivable, Modified [Line Items]
Total modified loans balance	6
Personal, small business and other | In offices outside North America | 30–89 days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	0
Personal, small business and other | In offices outside North America | 90+ days past due
Financing Receivable, Modified [Line Items]
Total modified loans balance	$ 0