BASIS OF PRESENTATION - Narrative (Details) - USD ($) $ in Millions				12 Months Ended
	Jan. 01, 2020	Mar. 01, 2019	Jan. 01, 2019	Dec. 31, 2023	Dec. 31, 2020	Dec. 31, 2019	Jan. 02, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill						$ 7,044		$ 6,923	$ 6,887
Cumulative effect of change in accounting standards			$ 5				$ 17
Right-of-use asset						699
Lease liability						721
Allowance for credit losses						$ 1,296		$ 1,333
Clarfeld
Business Acquisition [Line Items]
Consideration transferred			110
Goodwill			83
Intangible assets acquired			21
Bowstring
Business Acquisition [Line Items]
Consideration transferred		$ 40
Goodwill		35
Intangible assets acquired		$ 6
Accounting Standards Update 2016-02
Business Acquisition [Line Items]
Right-of-use asset			734
Lease liability			749
Forecast | Accounting Standards Update 2016-13
Business Acquisition [Line Items]
Basis point change in CET1				(0.24%)	(0.06%)
Retained Earnings
Business Acquisition [Line Items]
Cumulative effect of change in accounting standards							$ 12
Retained Earnings | Accounting Standards Update 2016-02
Business Acquisition [Line Items]
Cumulative effect of change in accounting standards			$ 12
Subsequent Event | Forecast | Accounting Standards Update 2016-13
Business Acquisition [Line Items]
Allowance for credit losses	$ 450
Capital impact phase in percentage	25.00%