LOANS - Consumer Loans, Delinquencies and Non-Accrual Details (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 733,905		$ 733,905		$ 694,488
Held at fair value	7,896		7,896		8,040
Reversal of accrued interest	400	$ 400	1,400	$ 1,200
Unallocated portfolio layer cumulative basis adjustments					(72)
Consumer loans
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	398,628		398,628		393,102
Non-accrual loans for which there is no ACLL	161		161		146
Non-accrual loans for which there is an ACLL	1,446		1,446		1,164
Total non-accrual	1,607		1,607		1,310
90 days  past due and accruing	2,578		2,578		2,907
Total excluding portfolio-layer hedges cumulative basis adjustments	398,036		398,036		393,326
Held at fair value	26		26		281
Unearned income	939		939		889
Accrued interest receivable	1,000		1,000		1,000
Unallocated portfolio layer cumulative basis adjustments	592		592		(224)
Consumer loans | Current
Financing Receivable, Past Due [Line Items]
Total excluding portfolio-layer hedges cumulative basis adjustments	391,214		391,214		386,444
Consumer loans | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Total excluding portfolio-layer hedges cumulative basis adjustments	3,222		3,222		3,175
Consumer loans | 90+ days past due
Financing Receivable, Past Due [Line Items]
Total excluding portfolio-layer hedges cumulative basis adjustments	3,395		3,395		3,472
Consumer loans | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Total excluding portfolio-layer hedges cumulative basis adjustments	205		205		235
Consumer loans | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	320,595		320,595		321,948
Non-accrual loans for which there is no ACLL	161		161		146
Non-accrual loans for which there is an ACLL	845		845		677
Total non-accrual	1,006		1,006		823
90 days  past due and accruing	2,487		2,487		2,835
Consumer loans | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	314,575		314,575		315,704
Consumer loans | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,819		2,819		2,847
Consumer loans | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,996		2,996		3,162
Consumer loans | In North America offices | 90+ days past due | Banking
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	25,200		25,200		25,900
Consumer loans | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	205		205		235
Consumer loans | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	77,441		77,441		71,378
Non-accrual loans for which there is no ACLL	0		0		0
Non-accrual loans for which there is an ACLL	601		601		487
Total non-accrual	601		601		487
90 days  past due and accruing	91		91		72
Consumer loans | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	21,562		21,562		17,553
Consumer loans | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	76,639		76,639		70,740
Consumer loans | In offices outside North America | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	403		403		328
Consumer loans | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	399		399		310
Consumer loans | In offices outside North America | 90+ days past due | Banking
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	21,600		21,600		17,600
Consumer loans | In offices outside North America | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0		0		0
Consumer loans | Residential mortgages
Financing Receivable, Past Due [Line Items]
Held at fair value	26		26		281
Consumer loans | Residential mortgages | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	117,799		117,799		114,593
Non-accrual loans for which there is no ACLL	134		134		114
Non-accrual loans for which there is an ACLL	589		589		409
Total non-accrual	723		723		523
90 days  past due and accruing	110		110		128
Mortgage loans in process of foreclosure	100		100		200
Consumer loans | Residential mortgages | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	116,633		116,633		113,613
Consumer loans | Residential mortgages | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	413		413		397
Consumer loans | 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 loans | Residential mortgages | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	548		548		349
Consumer loans | Residential mortgages | In North America offices | 90+ days past due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income					100
Consumer loans | Residential mortgages | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	205		205		234
Consumer loans | Residential mortgages | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	24,078		24,078		24,456
Non-accrual loans for which there is no ACLL	0		0		0
Non-accrual loans for which there is an ACLL	177		177		155
Total non-accrual	177		177		155
90 days  past due and accruing	0		0		0
Mortgage loans in process of foreclosure	100		100		100
Consumer loans | Residential mortgages | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0		0		0
Consumer loans | Residential mortgages | In offices outside North America | Global Wealth Management Business
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	18,700		18,700		19,100
Consumer loans | Residential mortgages | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	23,959		23,959		24,358
Consumer loans | Residential mortgages | In offices outside North America | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	46		46		38
Consumer loans | Residential mortgages | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	73		73		60
Consumer loans | 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 loans | Home equity loans | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,916		2,916		3,141
Non-accrual loans for which there is no ACLL	22		22		25
Non-accrual loans for which there is an ACLL	89		89		114
Total non-accrual	111		111		139
90 days  past due and accruing	0		0		0
Home equity loans in process of foreclosure	100		100		100
Consumer loans | Home equity loans | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,848		2,848		3,060
Consumer loans | Home equity loans | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	28		28		23
Consumer loans | Home equity loans | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	40		40		58
Consumer loans | 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 loans | Credit cards | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	167,446		167,446		171,059
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	2,377		2,377		2,705
Consumer loans | Credit cards | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	162,786		162,786		166,021
Consumer loans | Credit cards | In North America offices | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,283		2,283		2,333
Consumer loans | Credit cards | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	2,377		2,377		2,705
Consumer loans | 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 loans | Credit cards | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	13,754		13,754		12,927
Non-accrual loans for which there is no ACLL	0		0		0
Non-accrual loans for which there is an ACLL	283		283		211
Total non-accrual	283		283		211
90 days  past due and accruing	91		91		72
Consumer loans | Credit cards | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0		0		0
Consumer loans | Credit cards | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	13,230		13,230		12,523
Consumer loans | Credit cards | In offices outside North America | 30–89 days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	238		238		190
Consumer loans | Credit cards | In offices outside North America | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	286		286		214
Consumer loans | 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 loans | Personal, small business and other | In North America offices
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	32,434		32,434		33,155
Non-accrual loans for which there is no ACLL	5		5		7
Non-accrual loans for which there is an ACLL	167		167		154
Total non-accrual	172		172		161
90 days  past due and accruing	0		0		2
Consumer loans | Personal, small business and other | In North America offices | Global Wealth Management Business
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 27,400		$ 27,400		$ 28,100
Consumer loans | 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	80.00%		80.00%		83.00%
Consumer loans | Personal, small business and other | In North America offices | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 32,308		$ 32,308		$ 33,010
Consumer loans | 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		95		94
Consumer loans | Personal, small business and other | In North America offices | 90+ days past due
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	31		31		50
Consumer loans | Personal, small business and other | In North America offices | Past Due | Government-guaranteed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	0		0		1
Consumer loans | Personal, small business and other | In offices outside North America
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	39,609		39,609		33,995
Non-accrual loans for which there is no ACLL	0		0		0
Non-accrual loans for which there is an ACLL	141		141		121
Total non-accrual	141		141		121
90 days  past due and accruing	0		0		0
Consumer loans | Personal, small business and other | In offices outside North America | Classifiably managed
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	21,562		21,562		$ 17,553
Consumer loans | 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					83.00%
Consumer loans | 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	$ 30,000		$ 30,000		$ 25,400
Consumer loans | 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					$ 17,600
Consumer loans | 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	54.00%		54.00%		56.00%
Consumer loans | Personal, small business and other | In offices outside North America | Current
Financing Receivable, Past Due [Line Items]
Loans, net of unearned income	$ 39,450		$ 39,450		$ 33,859
Consumer loans | 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	119		119		100
Consumer loans | 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	40		40		36
Consumer loans | 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