LOANS - Consumer Loans Credit Scores (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 660,612	$ 657,221
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	374,591	368,067
Consumer | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,454	2,153
Consumer | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	296,792	289,014
Consumer | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,133	1,888
Consumer | In North America offices | 90+ days past due | Personal Banking and Wealth Management
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	30,600	31,500
Consumer | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	77,799	79,053
Consumer | In offices outside North America | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	321	265
Consumer | In offices outside North America | 90+ days past due | Personal Banking and Wealth Management
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	17,900	17,800
Consumer | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	102,680	96,039
Consumer | Residential mortgages | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	102,680	96,039
Consumer | Residential mortgages | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	285	316
Consumer | Residential mortgages | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	27,090	28,114
Consumer | Residential mortgages | In offices outside North America | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	92	106
Consumer | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	4,000	4,580
Consumer | Home equity loans | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	4,000	4,580
Consumer | Home equity loans | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	96	135
Consumer | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	152,352	150,098
Consumer | Credit cards | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	152,951	150,643
Consumer | Credit cards | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,723	1,415
Consumer | Credit cards | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	63	75
Loans, net of unearned income	13,714	12,955
Consumer | Credit cards | In offices outside North America | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	190	149
Consumer | Credit cards | Canada
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	599	545
Consumer | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	49	67
Loans, net of unearned income	36,242	36,812
Consumer | Personal, small business and other | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	37,161	37,752
Consumer | Personal, small business and other | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	29	22
Consumer | Personal, small business and other | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 36,995	$ 37,984
Consumer | Personal, small business and other | In offices outside North America | Internal Investment Grade
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage of loans rated investment grade	99.00%	98.00%
Consumer | Personal, small business and other | In offices outside North America | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 39	$ 10
Consumer | Personal, small business and other | Canada
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	919	940
Consumer | Classifiably Managed and Delinquency Managed | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	79,300	80,500
Consumer | Less than 680
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	35,545	34,306
Consumer | Less than 680 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	151	691
One year prior to current fiscal year	717	639
Two years prior to current fiscal year	602	431
Three years prior to current fiscal year	393	321
Four years prior to current fiscal year	312	302
Prior	2,185	2,020
Loans, net of unearned income	4,360	4,404
Consumer | Less than 680 | Home equity loans (pre-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	490	552
Consumer | Less than 680 | Home equity loans (post-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	71	62
Consumer | Less than 680 | Home equity term loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One year prior to current fiscal year	0	0
Two years prior to current fiscal year	0	1
Three years prior to current fiscal year	1	1
Four years prior to current fiscal year	1	1
Prior	90	103
Loans, net of unearned income	92	106
Consumer | Less than 680 | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	653	720
Consumer | Less than 680 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	29,111	27,901
Consumer | Less than 680 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	913	766
Loans, net of unearned income	30,024	28,667
Consumer | Less than 680 | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	10	247
One year prior to current fiscal year	268	96
Two years prior to current fiscal year	80	15
Three years prior to current fiscal year	11	21
Four years prior to current fiscal year	13	10
Prior	126	126
Loans, net of unearned income	508	515
Consumer | 680 to 760
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	90,663	89,490
Consumer | 680 to 760 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,704	7,530
One year prior to current fiscal year	6,659	5,933
Two years prior to current fiscal year	5,747	4,621
Three years prior to current fiscal year	4,360	2,505
Four years prior to current fiscal year	2,345	1,072
Prior	7,099	6,551
Loans, net of unearned income	28,914	28,212
Consumer | 680 to 760 | Home equity loans (pre-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,212	1,536
Consumer | 680 to 760 | Home equity loans (post-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	76	65
Consumer | 680 to 760 | Home equity term loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One year prior to current fiscal year	0	1
Two years prior to current fiscal year	1	2
Three years prior to current fiscal year	2	2
Four years prior to current fiscal year	1	2
Prior	133	144
Loans, net of unearned income	137	151
Consumer | 680 to 760 | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,425	1,752
Consumer | 680 to 760 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	59,069	58,213
Consumer | 680 to 760 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	357	354
Loans, net of unearned income	59,426	58,567
Consumer | 680 to 760 | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	45	546
One year prior to current fiscal year	515	170
Two years prior to current fiscal year	129	20
Three years prior to current fiscal year	14	23
Four years prior to current fiscal year	14	10
Prior	181	190
Loans, net of unearned income	898	959
Consumer | Greater than 760
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	125,740	120,733
Consumer | Greater than 760 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	5,671	12,928
One year prior to current fiscal year	13,618	12,672
Two years prior to current fiscal year	12,540	10,936
Three years prior to current fiscal year	10,860	5,445
Four years prior to current fiscal year	5,350	1,899
Prior	13,907	12,649
Loans, net of unearned income	61,946	56,529
Consumer | Greater than 760 | Home equity loans (pre-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,736	1,876
Consumer | Greater than 760 | Home equity loans (post-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	45	40
Consumer | Greater than 760 | Home equity term loans
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
One year prior to current fiscal year	0	1
Two years prior to current fiscal year	1	2
Three years prior to current fiscal year	2	2
Four years prior to current fiscal year	1	1
Prior	104	111
Loans, net of unearned income	108	117
Consumer | Greater than 760 | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,889	2,033
Consumer | Greater than 760 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	60,712	60,896
Consumer | Greater than 760 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	54	54
Loans, net of unearned income	60,766	60,950
Consumer | Greater than 760 | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	105	800
One year prior to current fiscal year	712	210
Two years prior to current fiscal year	151	30
Three years prior to current fiscal year	20	28
Four years prior to current fiscal year	16	9
Prior	135	144
Loans, net of unearned income	1,139	1,221
Consumer | Classifiably managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	30,596	31,478
Consumer | Classifiably managed | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	17,902	17,762
Consumer | Classifiably managed | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0
Consumer | Classifiably managed | Residential mortgages | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0	0
Consumer | Classifiably managed | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0
Consumer | Classifiably managed | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0
Consumer | Classifiably managed | Credit cards | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	0	0
Consumer | Classifiably managed | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	30,596	31,478
Consumer | Classifiably managed | Personal, small business and other | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	17,902	17,762
Consumer | FICO not available
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	12,730	11,522
Consumer | FICO not available | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	7,460	6,894
Consumer | FICO not available | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	33	75
Consumer | FICO not available | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,136	1,914
Consumer | FICO not available | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	3,101	2,639
Consumer | Total loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 295,274	$ 287,529