COMMISSIONS AND FEES; ADMINISTRATION AND OTHER FIDUCIARY FEES - Administration and Other Fiduciary Fees (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Commissions and fees
Total administration and other fiduciary fees	$ 966	$ 961
Custody fees
Commissions and fees
Total administration and other fiduciary fees	473	457
Custody fees | ICG
Commissions and fees
Total administration and other fiduciary fees	447	432
Custody fees | PBWM
Commissions and fees
Total administration and other fiduciary fees	23	21
Custody fees | Legacy Franchises
Commissions and fees
Total administration and other fiduciary fees	3	4
Custody fees | Corporate/Other
Commissions and fees
Total administration and other fiduciary fees	0	0
Fiduciary fees
Commissions and fees
Total administration and other fiduciary fees	349	359
Fiduciary fees | ICG
Commissions and fees
Total administration and other fiduciary fees	64	61
Fiduciary fees | PBWM
Commissions and fees
Total administration and other fiduciary fees	205	191
Fiduciary fees | Legacy Franchises
Commissions and fees
Total administration and other fiduciary fees	80	107
Fiduciary fees | Corporate/Other
Commissions and fees
Total administration and other fiduciary fees	0	0
Guarantee fees
Commissions and fees
Total administration and other fiduciary fees	144	145
Guarantee fees | ICG
Commissions and fees
Total administration and other fiduciary fees	132	132
Guarantee fees | PBWM
Commissions and fees
Total administration and other fiduciary fees	10	11
Guarantee fees | Legacy Franchises
Commissions and fees
Total administration and other fiduciary fees	2	2
Guarantee fees | Corporate/Other
Commissions and fees
Total administration and other fiduciary fees	0	0
Administration and other fiduciary fees
Commissions and fees
Total administration and other fiduciary fees	966	961
Revenue not accounted for under ASC 606, revenue from contracts with customers	144	145
Administration and other fiduciary fees | ICG
Commissions and fees
Total administration and other fiduciary fees	643	625
Administration and other fiduciary fees | PBWM
Commissions and fees
Total administration and other fiduciary fees	238	223
Administration and other fiduciary fees | Legacy Franchises
Commissions and fees
Total administration and other fiduciary fees	85	113
Administration and other fiduciary fees | Corporate/Other
Commissions and fees
Total administration and other fiduciary fees	$ 0	$ 0