LOANS - Consumer Loans Troubled Debt Restructurings (Details) - Consumer $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) loan
In North America offices
Financing Receivable, Modified [Line Items]
Number of loans modified | loan	41,336
Post-modification recorded investment	$ 264
In North America offices | Residential mortgages
Financing Receivable, Modified [Line Items]
Number of loans modified | loan	346
Post-modification recorded investment	$ 81
Average interest rate reduction	0.00%
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	$ 1
In North America offices | Residential mortgages | New OCC guidance
Financing Receivable, Modified [Line Items]
Post-modification recorded investment for borrowers that have gone through Chapter 7 bankruptcy	$ 1
In North America offices | Home equity loans
Financing Receivable, Modified [Line Items]
Number of loans modified | loan	104
Post-modification recorded investment	$ 9
Average interest rate reduction	0.00%
In North America offices | Credit cards
Financing Receivable, Modified [Line Items]
Number of loans modified | loan	40,740
Post-modification recorded investment	$ 173
Average interest rate reduction	17.00%
In North America offices | Personal, small business and other
Financing Receivable, Modified [Line Items]
Number of loans modified | loan	146
Post-modification recorded investment	$ 1
Average interest rate reduction	5.00%
In offices outside North America
Financing Receivable, Modified [Line Items]
Number of loans modified | loan	5,855
Post-modification recorded investment	$ 37
In offices outside North America | Residential mortgages
Financing Receivable, Modified [Line Items]
Number of loans modified | loan	183
Post-modification recorded investment	$ 6
Average interest rate reduction	0.00%
In offices outside North America | Credit cards
Financing Receivable, Modified [Line Items]
Number of loans modified | loan	5,000
Post-modification recorded investment	$ 22
Average interest rate reduction	19.00%
In offices outside North America | Personal, small business and other
Financing Receivable, Modified [Line Items]
Number of loans modified | loan	672
Post-modification recorded investment	$ 9
Average interest rate reduction	8.00%
Deferred principal | In North America offices
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	$ 0
Deferred principal | In North America offices | Residential mortgages
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Deferred principal | In North America offices | Home equity loans
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Deferred principal | In North America offices | Credit cards
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Deferred principal | In North America offices | Personal, small business and other
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Deferred principal | In offices outside North America
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Deferred principal | In offices outside North America | Residential mortgages
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Deferred principal | In offices outside North America | Credit cards
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Deferred principal | In offices outside North America | Personal, small business and other
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Contingent principal forgiveness | In North America offices
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Contingent principal forgiveness | In North America offices | Residential mortgages
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Contingent principal forgiveness | In North America offices | Home equity loans
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Contingent principal forgiveness | In North America offices | Credit cards
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Contingent principal forgiveness | In North America offices | Personal, small business and other
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Contingent principal forgiveness | In offices outside North America
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Contingent principal forgiveness | In offices outside North America | Residential mortgages
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Contingent principal forgiveness | In offices outside North America | Credit cards
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Contingent principal forgiveness | In offices outside North America | Personal, small business and other
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Principal forgiveness | In North America offices
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Principal forgiveness | In North America offices | Residential mortgages
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Principal forgiveness | In North America offices | Home equity loans
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Principal forgiveness | In North America offices | Credit cards
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Principal forgiveness | In North America offices | Personal, small business and other
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Principal forgiveness | In offices outside North America
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	1
Principal forgiveness | In offices outside North America | Residential mortgages
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	0
Principal forgiveness | In offices outside North America | Credit cards
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	1
Principal forgiveness | In offices outside North America | Personal, small business and other
Financing Receivable, Modified [Line Items]
Post-modification recorded investment	$ 0