LOANS - Consumer Loans, Delinquencies and Non-Accrual Details (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 660,612		$ 660,612		$ 657,221
Loans held at fair value	5,766		5,766		5,360
Reversal of accrued interest	300	$ 200	500	$ 300
Consumer
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	374,591		374,591		368,067
Non-accrual loans for which there is no ACLL	151		151		140
Non-accrual loans for which there is an ACLL	1,170		1,170		1,177
Total non-accrual	1,321		1,321		1,317
90 days  past due and accruing	1,947		1,947		1,658
Loans held at fair value	237		237		237
Unearned income	769		769		712
Accrued interest receivable	1,000		1,000		1,000
Consumer | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	30,596		30,596		31,478
Consumer | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	369,316		369,316		363,256
Consumer | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,572		2,572		2,372
Consumer | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,454		2,454		2,153
Consumer | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	249		249		286
Consumer | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	296,792		296,792		289,014
Non-accrual loans for which there is no ACLL	151		151		140
Non-accrual loans for which there is an ACLL	553		553		608
Total non-accrual	704		704		748
90 days  past due and accruing	1,869		1,869		1,589
Consumer | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	292,174		292,174		284,782
Consumer | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,236		2,236		2,058
Consumer | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,133		2,133		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	30,600		30,600		31,500
Consumer | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	249		249		286
Consumer | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	77,799		77,799		79,053
Non-accrual loans for which there is no ACLL	0		0		0
Non-accrual loans for which there is an ACLL	617		617		569
Total non-accrual	617		617		569
90 days  past due and accruing	78		78		69
Consumer | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	17,902		17,902		17,762
Consumer | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	77,142		77,142		78,474
Consumer | In offices outside North America | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	336		336		314
Consumer | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	321		321		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	17,900		17,900		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		0
Consumer | Residential mortgages
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	102,680		102,680		96,039
Loans held at fair value	237		237		237
Consumer | Residential mortgages | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0		0
Consumer | Residential mortgages | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	102,680		102,680		96,039
Non-accrual loans for which there is no ACLL	101		101		86
Non-accrual loans for which there is an ACLL	380		380		434
Total non-accrual	481		481		520
90 days  past due and accruing	139		139		163
Mortgage loans in process of foreclosure	200		200		100
Consumer | Residential mortgages | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	101,780		101,780		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	371		371		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		100
Consumer | Residential mortgages | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	285		285		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		100		200
Consumer | Residential mortgages | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	244		244		279
Consumer | Residential mortgages | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	27,090		27,090		28,114
Non-accrual loans for which there is no ACLL	0		0		0
Non-accrual loans for which there is an ACLL	328		328		305
Total non-accrual	328		328		305
90 days  past due and accruing	18		18		13
Mortgage loans in process of foreclosure	0		0		0
Consumer | Residential mortgages | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0		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	20,400		20,400		19,800
Consumer | Residential mortgages | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	26,950		26,950		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	48		48		62
Consumer | Residential mortgages | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	92		92		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		0
Consumer | Home equity loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	4,000		4,000		4,580
Consumer | Home equity loans | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0		0
Consumer | Home equity loans | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	4,000		4,000		4,580
Non-accrual loans for which there is no ACLL	46		46		51
Non-accrual loans for which there is an ACLL	139		139		151
Total non-accrual	185		185		202
90 days  past due and accruing	0		0		0
Home equity loans in process of foreclosure	100		100		100
Consumer | Home equity loans | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	3,869		3,869		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	35		35		38
Consumer | Home equity loans | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	96		96		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		0
Consumer | Credit cards
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	152,352		152,352		150,098
Consumer | Credit cards | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0		0
Consumer | Credit cards | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	152,951		152,951		150,643
Non-accrual loans for which there is no ACLL	0		0		0
Non-accrual loans for which there is an ACLL	0		0		0
Total non-accrual	0		0		0
90 days  past due and accruing	1,723		1,723		1,415
Consumer | Credit cards | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	149,487		149,487		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	1,741		1,741		1,511
Consumer | Credit cards | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	1,723		1,723		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		0
Consumer | Credit cards | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	13,714		13,714		12,955
Non-accrual loans for which there is no ACLL	0		0		0
Non-accrual loans for which there is an ACLL	172		172		127
Total non-accrual	172		172		127
90 days  past due and accruing	60		60		56
Consumer | Credit cards | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0		0		0
Consumer | Credit cards | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	13,344		13,344		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	180		180		147
Consumer | Credit cards | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	190		190		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		0
Consumer | Personal, small business and other
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	36,242		36,242		36,812
Consumer | Personal, small business and other | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	30,596		30,596		31,478
Consumer | Personal, small business and other | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	37,161		37,161		37,752
Non-accrual loans for which there is no ACLL	4		4		3
Non-accrual loans for which there is an ACLL	34		34		23
Total non-accrual	38		38		26
90 days  past due and accruing	7		7		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	33,100		33,100		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	$ 30,600		$ 30,600		$ 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	99.00%		99.00%		98.00%
Consumer | Personal, small business and other | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 37,038		$ 37,038		$ 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	89		89		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		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	5		5		7
Consumer | Personal, small business and other | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	36,995		36,995		37,984
Non-accrual loans for which there is no ACLL	0		0		0
Non-accrual loans for which there is an ACLL	117		117		137
Total non-accrual	117		117		137
90 days  past due and accruing	0		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	$ 17,902		$ 17,902		$ 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	99.00%		99.00%		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	$ 26,000		$ 26,000		$ 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	$ 17,900		$ 17,900		$ 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	93.00%		93.00%		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	$ 36,848		$ 36,848		$ 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	108		108		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	39		39		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		$ 0