LOANS - Consumer Loans Outside of North America (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 645,960	$ 667,767
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	357,583	376,534
Consumer | 30 to 89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,077	1,999
Consumer | 90 days or more past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,932	1,963
Consumer | Classifiably Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	33,910	35,324
Consumer | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	93,381	83,361
Consumer | Residential mortgages | Classifiably Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0	0
Consumer | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	139,856	133,351
Consumer | Credit cards | Classifiably Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0	0
Consumer | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	39,199	39,806
Consumer | Personal, small business and other | Classifiably Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	33,910	35,324
In offices outside North America | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 78,894	112,847
NCL ratio	0.91%		1.10%
In offices outside North America | Consumer | 30 to 89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 293	$ 502
Past due ratio	0.49%	0.57%
In offices outside North America | Consumer | 90 days or more past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 291	$ 421
Past due ratio	0.49%	0.48%
In offices outside North America | Consumer | Classifiably Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 19,432	$ 24,482
In offices outside North America | Consumer | FICO Score, Delinquency Managed Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	59,462	88,365
In offices outside North America | Consumer | Classifiably Managed and Delinquency Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	80,400	114,300
In offices outside North America | Consumer | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 27,281	37,889
NCL ratio	0.18%		0.10%
In offices outside North America | Consumer | Residential mortgages | 30 to 89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 51	$ 165
Past due ratio	0.19%	0.44%
In offices outside North America | Consumer | Residential mortgages | 90 days or more past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 86	$ 158
Past due ratio	0.32%	0.42%
In offices outside North America | Consumer | Residential mortgages | Classifiably Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 0	$ 0
In offices outside North America | Consumer | Residential mortgages | FICO Score, Delinquency Managed Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	27,281	37,889
In offices outside North America | Consumer | Residential mortgages | Global Wealth Management Business
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	19,300	19,800
In offices outside North America | Consumer | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 11,764	17,808
NCL ratio	3.22%		3.99%
In offices outside North America | Consumer | Credit cards | 30 to 89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 131	$ 192
Past due ratio	1.11%	1.08%
In offices outside North America | Consumer | Credit cards | 90 days or more past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 125	$ 188
Past due ratio	1.06%	1.06%
In offices outside North America | Consumer | Credit cards | Classifiably Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 0	$ 0
In offices outside North America | Consumer | Credit cards | FICO Score, Delinquency Managed Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	11,764	17,808
In offices outside North America | Consumer | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 39,849	57,150
NCL ratio	0.74%		0.92%
In offices outside North America | Consumer | Personal, small business and other | 30 to 89 days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 111	$ 145
Past due ratio	0.54%	0.44%
In offices outside North America | Consumer | Personal, small business and other | 90 days or more past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 80	$ 75
Past due ratio	0.39%	0.23%
In offices outside North America | Consumer | Personal, small business and other | Classifiably Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 19,432	$ 24,482
In offices outside North America | Consumer | Personal, small business and other | FICO Score, Delinquency Managed Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	20,417	32,668
In offices outside North America | Consumer | Personal, small business and other | Global Wealth Management Business
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	28,500	34,600
In offices outside North America | Consumer | Personal, small business and other | Global Wealth Management Business | Classifiably Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	19,400	24,500
In offices outside North America | Consumer | Personal, small business and other | Global Wealth Management Business | Classifiably Managed and Delinquency Managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 28,500	$ 34,600