LOANS - Loan-to-Value Ratios Consumer Loans (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 | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	77,799	79,053
Consumer | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	95,159	90,741
Consumer | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	9,929	8,385
Consumer | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	209	263
Consumer | LTV not available | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,383	1,230
Consumer | Total | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	106,680	100,619
Consumer | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	102,680	96,039
Consumer | Residential mortgages | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	102,680	96,039
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 | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	6,634	15,644
One year prior to current fiscal year	16,146	19,104
Two years prior to current fiscal year	18,846	16,935
Three years prior to current fiscal year	16,451	8,789
Four years prior to current fiscal year	8,395	3,598
Prior	25,029	22,367
Loans, net of unearned income	91,501	86,437
Consumer | Residential mortgages | Less than or equal to 80% | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,847	3,106
One year prior to current fiscal year	3,356	4,144
Two years prior to current fiscal year	3,713	3,293
Three years prior to current fiscal year	2,845	3,048
Four years prior to current fiscal year	2,775	2,074
Prior	8,942	9,201
Loans, net of unearned income	$ 23,478	$ 24,866
Loan to value ratio	52.00%	51.00%
Consumer | Residential mortgages | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 1,975	$ 6,497
One year prior to current fiscal year	5,916	1,227
Two years prior to current fiscal year	1,096	267
Three years prior to current fiscal year	362	140
Four years prior to current fiscal year	226	74
Prior	318	132
Loans, net of unearned income	9,893	8,337
Consumer | Residential mortgages | Greater than 80% but less than or equal to 100% | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	620	975
One year prior to current fiscal year	1,102	964
Two years prior to current fiscal year	1,069	502
Three years prior to current fiscal year	385	92
Four years prior to current fiscal year	63	48
Prior	44	36
Loans, net of unearned income	3,283	2,617
Consumer | Residential mortgages | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	6	40
One year prior to current fiscal year	43	33
Two years prior to current fiscal year	33	1
Three years prior to current fiscal year	1	23
Four years prior to current fiscal year	26	9
Prior	78	74
Loans, net of unearned income	187	180
Consumer | Residential mortgages | Greater than 100% | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	294
One year prior to current fiscal year	33	273
Two years prior to current fiscal year	44	25
Three years prior to current fiscal year	0	1
Four years prior to current fiscal year	1	0
Prior	8	7
Loans, net of unearned income	86	600
Consumer | Residential mortgages | LTV not available | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	1,099	1,085
Consumer | Residential mortgages | LTV not available | In offices outside North America
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	243	31
Consumer | Home equity loans (pre-reset) | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	3,167	3,677
Consumer | Home equity loans (pre-reset) | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	28	36
Consumer | Home equity loans (pre-reset) | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	9	56
Consumer | Home equity loans (post-reset) | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	491	627
Consumer | Home equity loans (post-reset) | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	8	12
Consumer | Home equity loans (post-reset) | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	13	27
Consumer | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	4,000	4,580
Consumer | Home equity loans | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	4,000	4,580
Consumer | Home equity loans | Less than or equal to 80% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	3,658	4,304
Consumer | Home equity loans | Greater than 80% but less than or equal to 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	36	48
Consumer | Home equity loans | Greater than 100% | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	22	83
Consumer | Home equity loans | LTV not available | UNITED STATES
Financing Receivable, Credit Quality Indicator [Line Items]
Loans, net of unearned income	$ 284	$ 145