PARENT COMPANY FINANCIALS - Condensed Cash Flow Statements (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
OPERATING ACTIVITIES
Net income		$ 1,608	$ 2,073	$ 2,319
Adjustments to reconcile net income to net change in cash due to operating activities:
Deferred income tax expense (benefit)		(242)	57	(429)
Net increase (decrease) in other liabilities		(339)	1,036	757
Net (increase) decrease in other assets		612	(1,894)	(1,719)
Net change due to operating activities		2,961	4,119	2,275
INVESTING ACTIVITIES
Acquisitions, net of cash acquired	[1]	0	(255)	(165)
Other investing, net		(61)	(771)	(316)
Net change due to investing activities		5,248	(12,637)	(10,486)
FINANCING ACTIVITIES
Proceeds from issuance of long-term borrowed funds		25,983	24,617	0
Repayments of long-term borrowed funds		(28,418)	(19,691)	(1,352)
Treasury stock purchased		(906)	(153)	(295)
Net proceeds from issuance of preferred stock		0	0	296
Redemption of preferred stock		0	0	(250)
Dividends paid to preferred stockholders		(120)	(113)	(113)
Other		21	(25)	(22)
Net change due to financing activities		(7,128)	9,907	4,636
Net change in cash and cash equivalents	[2]	1,081	1,389	(3,575)
Cash and cash equivalents at beginning of period	[2]	10,547	9,158	12,733
Cash and cash equivalents at end of period	[2]	11,628	10,547	9,158
Parent company
OPERATING ACTIVITIES
Net income		1,608	2,073	2,319
Adjustments to reconcile net income to net change in cash due to operating activities:
Deferred income tax expense (benefit)		(4)	(11)	0
Equity in undistributed (income) losses of subsidiaries		1,202	(1,651)	(1,207)
Other, net		96	92	67
Net increase (decrease) in other liabilities		(17)	(7)	34
Net (increase) decrease in other assets		17	(44)	12
Net change due to operating activities		2,902	452	1,225
INVESTING ACTIVITIES
Investments in and advances to subsidiaries		(76)	(156)	(196)
Repayment of investments in and advances to subsidiaries		30	121	125
Acquisitions, net of cash acquired		0	(23)	(165)
Other investing, net		0	(1)	(1)
Net change due to investing activities		(46)	(59)	(237)
FINANCING ACTIVITIES
Proceeds from issuance of long-term borrowed funds		0	414	0
Repayments of long-term borrowed funds		0	(182)	(350)
Treasury stock purchased		(906)	(153)	(295)
Net proceeds from issuance of preferred stock		0	0	296
Redemption of preferred stock		0	0	(250)
Dividends paid to common stockholders		(808)	(779)	(670)
Dividends paid to preferred stockholders		(120)	(113)	(113)
Other		21	(25)	(20)
Net change due to financing activities		(1,813)	(838)	(1,402)
Net change in cash and cash equivalents		1,043	(445)	(414)
Cash and cash equivalents at beginning of period		1,821	2,266	2,680
Cash and cash equivalents at end of period		$ 2,864	$ 1,821	$ 2,266

[1] Primarily includes cash paid of $355 million to acquire Investors less $287 million in cash acquired, and $143 million and $23 million of cash paid for the HSBC transaction and acquisition of DH Capital, LLC, respectively, for the year ended December 31, 2022.

[2] Cash and cash equivalents include cash and due from banks and interest-bearing cash and due from banks as reflected on the Consolidated Balance Sheets