LOANS - Consumer Loans Credit Scores (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 651,995	$ 657,221
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	363,696	368,067
Consumer | 90+ days past due
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,375	2,153
Consumer | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	286,389	289,014
Consumer | In North America offices | 90+ days past due
Financing Receivable, Credit Quality Indicator [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, Credit Quality Indicator [Line Items]
Loans, net of unearned income	31,500	31,500
Consumer | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	77,307	79,053
Consumer | In offices outside North America | 90+ days past due
Financing Receivable, Credit Quality Indicator [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, Credit Quality Indicator [Line Items]
Loans, net of unearned income	17,800	17,800
Consumer | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	98,790	96,039
Consumer | Residential mortgages | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	98,790	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	332	316
Consumer | Residential mortgages | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	26,913	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	111	106
Consumer | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	4,244	4,580
Consumer | Home equity loans | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	4,244	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	121	135
Consumer | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	145,023	150,098
Consumer | Credit cards | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	145,543	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	1,608	1,415
Consumer | Credit cards | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	48	75
Loans, net of unearned income	13,033	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	166	149
Consumer | Credit cards | Canada
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	520	545
Consumer | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	56	67
Loans, net of unearned income	36,877	36,812
Consumer | Personal, small business and other | In North America offices
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	37,812	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	$ 37,361	$ 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	95.00%	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	$ 8	$ 10
Consumer | Personal, small business and other | Canada
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	935	940
Consumer | Classifiably Managed and Delinquency Managed | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	78,800	80,500
Consumer | Less than 680
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	35,814	34,306
Consumer | Less than 680 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	56	691
One year prior to current fiscal year	823	639
Two years prior to current fiscal year	669	431
Three years prior to current fiscal year	400	321
Four years prior to current fiscal year	353	302
Prior	2,341	2,020
Loans, net of unearned income	4,642	4,404
Consumer | Less than 680 | Home equity loans (pre-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	529	552
Consumer | Less than 680 | Home equity loans (post-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	63	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	0	1
Four years prior to current fiscal year	1	1
Prior	102	103
Loans, net of unearned income	103	106
Consumer | Less than 680 | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	695	720
Consumer | Less than 680 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	29,044	27,901
Consumer | Less than 680 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	856	766
Loans, net of unearned income	29,900	28,667
Consumer | Less than 680 | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	11	247
One year prior to current fiscal year	307	96
Two years prior to current fiscal year	94	15
Three years prior to current fiscal year	13	21
Four years prior to current fiscal year	17	10
Prior	135	126
Loans, net of unearned income	577	515
Consumer | 680 to 760
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	87,626	89,490
Consumer | 680 to 760 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,112	7,530
One year prior to current fiscal year	6,981	5,933
Two years prior to current fiscal year	5,690	4,621
Three years prior to current fiscal year	4,410	2,505
Four years prior to current fiscal year	2,382	1,072
Prior	7,061	6,551
Loans, net of unearned income	27,636	28,212
Consumer | 680 to 760 | Home equity loans (pre-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,407	1,536
Consumer | 680 to 760 | Home equity loans (post-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	70	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	137	144
Loans, net of unearned income	141	151
Consumer | 680 to 760 | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,618	1,752
Consumer | 680 to 760 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	57,031	58,213
Consumer | 680 to 760 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	346	354
Loans, net of unearned income	57,377	58,567
Consumer | 680 to 760 | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	51	546
One year prior to current fiscal year	576	170
Two years prior to current fiscal year	147	20
Three years prior to current fiscal year	16	23
Four years prior to current fiscal year	18	10
Prior	187	190
Loans, net of unearned income	995	959
Consumer | Greater than 760
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	117,736	120,733
Consumer | Greater than 760 | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2,258	12,928
One year prior to current fiscal year	13,463	12,672
Two years prior to current fiscal year	12,698	10,936
Three years prior to current fiscal year	10,981	5,445
Four years prior to current fiscal year	5,388	1,899
Prior	14,100	12,649
Loans, net of unearned income	58,888	56,529
Consumer | Greater than 760 | Home equity loans (pre-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,739	1,876
Consumer | Greater than 760 | Home equity loans (post-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	41	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	107	111
Loans, net of unearned income	111	117
Consumer | Greater than 760 | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,891	2,033
Consumer | Greater than 760 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	55,624	60,896
Consumer | Greater than 760 | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans	51	54
Loans, net of unearned income	55,675	60,950
Consumer | Greater than 760 | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	120	800
One year prior to current fiscal year	812	210
Two years prior to current fiscal year	174	30
Three years prior to current fiscal year	24	28
Four years prior to current fiscal year	21	9
Prior	131	144
Loans, net of unearned income	1,282	1,221
Consumer | Classifiably managed
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	31,452	31,478
Consumer | Classifiably managed | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	17,808	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	31,452	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	17,808	17,762
Consumer | FICO not available
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	12,306	11,522
Consumer | FICO not available | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	7,624	6,894
Consumer | FICO not available | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	40	75
Consumer | FICO not available | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,071	1,914
Consumer | FICO not available | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	2,571	2,639
Consumer | Total loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 284,934	$ 287,529