COMMISSIONS AND FEES; ADMINISTRATION AND OTHER FIDUCIARY FEES - Administration and Other Fiduciary Fees (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Commissions and fees
Total administration and other fiduciary fees	$ 971	$ 915	$ 2,856	$ 2,904
Custody fees
Commissions and fees
Total administration and other fiduciary fees	469	445	1,424	1,449
Custody fees | ICG
Commissions and fees
Total administration and other fiduciary fees	447	422	1,349	1,375
Custody fees | PBWM
Commissions and fees
Total administration and other fiduciary fees	20	21	62	67
Custody fees | Legacy Franchises
Commissions and fees
Total administration and other fiduciary fees	2	2	13	7
Fiduciary fees
Commissions and fees
Total administration and other fiduciary fees	370	334	1,024	1,026
Fiduciary fees | ICG
Commissions and fees
Total administration and other fiduciary fees	73	78	217	210
Fiduciary fees | PBWM
Commissions and fees
Total administration and other fiduciary fees	199	179	537	580
Fiduciary fees | Legacy Franchises
Commissions and fees
Total administration and other fiduciary fees	98	77	270	236
Guarantee fees
Commissions and fees
Total administration and other fiduciary fees	132	136	408	429
Guarantee fees | ICG
Commissions and fees
Total administration and other fiduciary fees	124	124	382	391
Guarantee fees | PBWM
Commissions and fees
Total administration and other fiduciary fees	6	10	21	34
Guarantee fees | Legacy Franchises
Commissions and fees
Total administration and other fiduciary fees	1	2	4	4
Administration and other fiduciary fees
Commissions and fees
Total administration and other fiduciary fees	971	915	2,856	2,904
Revenue not accounted for under ASC 606, revenue from contracts with customers	132	136	408	429
Administration and other fiduciary fees | ICG
Commissions and fees
Total administration and other fiduciary fees	644	624	1,948	1,976
Administration and other fiduciary fees | PBWM
Commissions and fees
Total administration and other fiduciary fees	225	210	620	681
Administration and other fiduciary fees | Legacy Franchises
Commissions and fees
Total administration and other fiduciary fees	$ 101	$ 81	$ 287	$ 247