LOANS - Consumer Loans Gross Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 2,000	$ 1,237	$ 5,513	$ 3,689
Consumer loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 1,928	$ 1,194	5,316	$ 3,541
Consumer loans | Residential mortgages
Financing Receivable, Credit Quality Indicator [Line Items]
2023			0
2022			2
2021			0
2020			1
2019			5
Prior			31
Total			39
Consumer loans | Home equity loans (pre-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Total			2
Consumer loans | Home equity loans (post-reset)
Financing Receivable, Credit Quality Indicator [Line Items]
Total			0
Consumer loans | Home equity term loans
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans			2
Consumer loans | Home equity loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total			4
Consumer loans | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Revolving loans converted to term loans			132
Total			4,598
Consumer loans | Credit cards
Financing Receivable, Credit Quality Indicator [Line Items]
Total			4,730
Consumer loans | Personal, small business and other
Financing Receivable, Credit Quality Indicator [Line Items]
2023			110
2022			146
2021			83
2020			34
2019			38
Prior			132
Total			$ 543