LOANS - Consumer Loans, Delinquencies and Non-Accrual Details (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 651,995	$ 657,221
Loans held at fair value	5,134	5,360
Reversal of accrued interest	200	600
Consumer
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	363,696	368,067
Non-accrual loans for which there is no ACLL	132	140
Non-accrual loans for which there is an ACLL	1,263	1,177
Total non-accrual	1,395	1,317
90 days  past due and accruing	1,857	1,658
Loans held at fair value	238	237
Unearned income	748	712
Accrued interest receivable	1,000	1,000
Consumer | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	31,452	31,478
Consumer | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	358,748	363,256
Consumer | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,325	2,372
Consumer | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,375	2,153
Consumer | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	248	286
Consumer | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	286,389	289,014
Non-accrual loans for which there is no ACLL	132	140
Non-accrual loans for which there is an ACLL	622	608
Total non-accrual	754	748
90 days  past due and accruing	1,780	1,589
Consumer | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	282,041	284,782
Consumer | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,010	2,058
Consumer | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,090	1,888
Consumer | In North America offices | 90+ days past due | Personal Banking and Wealth Management
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	31,500	31,500
Consumer | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	248	286
Consumer | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	77,307	79,053
Non-accrual loans for which there is no ACLL	0	0
Non-accrual loans for which there is an ACLL	641	569
Total non-accrual	641	569
90 days  past due and accruing	77	69
Consumer | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	17,808	17,762
Consumer | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	76,707	78,474
Consumer | In offices outside North America | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	315	314
Consumer | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	285	265
Consumer | In offices outside North America | 90+ days past due | Personal Banking and Wealth Management
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	17,800	17,800
Consumer | In offices outside North America | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
Consumer | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	98,790	96,039
Loans held at fair value	238	237
Consumer | Residential mortgages | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0
Consumer | Residential mortgages | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	98,790	96,039
Non-accrual loans for which there is no ACLL	83	86
Non-accrual loans for which there is an ACLL	448	434
Total non-accrual	531	520
90 days  past due and accruing	147	163
Mortgage loans in process of foreclosure	100	100
Consumer | Residential mortgages | In North America offices | Global Wealth Management Business
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income		19,800
Consumer | Residential mortgages | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	97,881	95,023
Consumer | Residential mortgages | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	336	421
Consumer | Residential mortgages | In North America offices | 30–89 days past due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	100	100
Consumer | Residential mortgages | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	332	316
Consumer | Residential mortgages | In North America offices | 90+ days past due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	100	200
Consumer | Residential mortgages | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	241	279
Consumer | Residential mortgages | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	26,913	28,114
Non-accrual loans for which there is no ACLL	0	0
Non-accrual loans for which there is an ACLL	359	305
Total non-accrual	359	305
90 days  past due and accruing	14	13
Mortgage loans in process of foreclosure	0
Consumer | Residential mortgages | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
Consumer | Residential mortgages | In offices outside North America | Global Wealth Management Business
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	20,300	19,800
Consumer | Residential mortgages | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	26,740	27,946
Consumer | Residential mortgages | In offices outside North America | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	62	62
Consumer | Residential mortgages | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	111	106
Consumer | Residential mortgages | In offices outside North America | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
Consumer | Home equity loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	4,244	4,580
Consumer | Home equity loans | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0
Consumer | Home equity loans | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	4,244	4,580
Non-accrual loans for which there is no ACLL	46	51
Non-accrual loans for which there is an ACLL	152	151
Total non-accrual	198	202
90 days  past due and accruing	0	0
Home equity loans in process of foreclosure	100	100
Consumer | Home equity loans | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	4,089	4,407
Consumer | Home equity loans | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	34	38
Consumer | Home equity loans | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	121	135
Consumer | Home equity loans | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
Consumer | Credit cards
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	145,023	150,098
Consumer | Credit cards | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0
Consumer | Credit cards | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	145,543	150,643
Non-accrual loans for which there is no ACLL	0	0
Non-accrual loans for which there is an ACLL	0	0
Total non-accrual	0	0
90 days  past due and accruing	1,608	1,415
Consumer | Credit cards | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	142,390	147,717
Consumer | Credit cards | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	1,545	1,511
Consumer | Credit cards | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	1,608	1,415
Consumer | Credit cards | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
Consumer | Credit cards | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	13,033	12,955
Non-accrual loans for which there is no ACLL	0	0
Non-accrual loans for which there is an ACLL	136	127
Total non-accrual	136	127
90 days  past due and accruing	63	56
Consumer | Credit cards | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
Consumer | Credit cards | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	12,704	12,659
Consumer | Credit cards | In offices outside North America | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	163	147
Consumer | Credit cards | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	166	149
Consumer | Credit cards | In offices outside North America | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0	0
Consumer | Personal, small business and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	36,877	36,812
Consumer | Personal, small business and other | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	31,452	31,478
Consumer | Personal, small business and other | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	37,812	37,752
Non-accrual loans for which there is no ACLL	3	3
Non-accrual loans for which there is an ACLL	22	23
Total non-accrual	25	26
90 days  past due and accruing	25	11
Consumer | Personal, small business and other | In North America offices | Global Wealth Management Business
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	33,900	34,000
Consumer | Personal, small business and other | In North America offices | Global Wealth Management Business | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 31,500	$ 31,500
Consumer | Personal, small business and other | In North America offices | Global Wealth Management Business | Internal Investment Grade
Financing Receivable, Past Due [Line Items]
Percentage of loans rated investment grade	95.00%	98.00%
Consumer | Personal, small business and other | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 37,681	$ 37,635
Consumer | Personal, small business and other | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	95	88
Consumer | Personal, small business and other | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	29	22
Consumer | Personal, small business and other | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	7	7
Consumer | Personal, small business and other | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	37,361	37,984
Non-accrual loans for which there is no ACLL	0	0
Non-accrual loans for which there is an ACLL	146	137
Total non-accrual	146	137
90 days  past due and accruing	0	0
Consumer | Personal, small business and other | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 17,808	$ 17,762
Consumer | Personal, small business and other | In offices outside North America | Internal Investment Grade
Financing Receivable, Past Due [Line Items]
Percentage of loans rated investment grade	95.00%	98.00%
Consumer | Personal, small business and other | In offices outside North America | Global Wealth Management Business
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 26,300	$ 26,600
Consumer | Personal, small business and other | In offices outside North America | Global Wealth Management Business | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 17,800	$ 17,800
Consumer | Personal, small business and other | In offices outside North America | Global Wealth Management Business | Internal Investment Grade
Financing Receivable, Past Due [Line Items]
Percentage of loans rated investment grade	89.00%	94.00%
Consumer | Personal, small business and other | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 37,263	$ 37,869
Consumer | Personal, small business and other | In offices outside North America | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	90	105
Consumer | Personal, small business and other | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	8	10
Consumer | Personal, small business and other | In offices outside North America | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 0	$ 0