PARENT COMPANY FINANCIALS - Condensed Cash Flow Statements (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
OPERATING ACTIVITIES
Net income			$ 1,509	$ 1,608	$ 2,073
Adjustments to reconcile net income to net change due to operating activities:
Deferred income tax expense (benefit)			(177)	(242)	57
Net increase (decrease) in other liabilities			(310)	(339)	1,036
Net (increase) decrease in other assets			(261)	612	(1,894)
Net change due to operating activities			2,001	2,961	4,119
INVESTING ACTIVITIES
Acquisitions, net of cash acquired	[1]		0	0	(255)
Other investing, net			(93)	(61)	(771)
Net change due to investing activities			2,987	5,248	(12,637)
FINANCING ACTIVITIES
Proceeds from issuance of long-term borrowed funds			13,185	25,983	24,617
Repayments of long-term borrowed funds			(14,286)	(28,418)	(19,691)
Treasury stock purchased			(1,050)	(906)	(153)
Net proceeds from issuance of preferred stock			392	0	0
Redemption of preferred stock			(300)	0	0
Dividends paid to preferred stockholders		$ (134)	(134)	(120)	(113)
Other			18	21	(25)
Net change due to financing activities			(6,015)	(7,128)	9,907
Net change in cash and cash equivalents	[2]		(1,027)	1,081	1,389
Cash and cash equivalents at beginning of period	[2]		11,628	10,547	9,158
Cash and cash equivalents at end of period	[2]	10,601	10,601	11,628	10,547
Parent company
OPERATING ACTIVITIES
Net income			1,509	1,608	2,073
Adjustments to reconcile net income to net change due to operating activities:
Deferred income tax expense (benefit)			(10)	(4)	(11)
Equity in undistributed (income) losses of subsidiaries			(975)	1,202	(1,651)
Other, net			108	96	92
Net increase (decrease) in other liabilities			92	(17)	(7)
Net (increase) decrease in other assets			(84)	17	(44)
Net change due to operating activities			640	2,902	452
INVESTING ACTIVITIES
Investments in and advances to subsidiaries			(2,249)	(76)	(156)
Repayment of investments in and advances to subsidiaries			120	30	121
Acquisitions, net of cash acquired			0	0	(23)
Other investing, net			2	0	(1)
Net change due to investing activities			(2,127)	(46)	(59)
FINANCING ACTIVITIES
Proceeds from issuance of long-term borrowed funds			3,231	0	414
Repayments of long-term borrowed funds			(107)	0	(182)
Treasury stock purchased			(1,050)	(906)	(153)
Net proceeds from issuance of preferred stock			392	0	0
Redemption of preferred stock			(300)	0	0
Dividends paid to common stockholders			(769)	(808)	(779)
Dividends paid to preferred stockholders			(134)	(120)	(113)
Other			18	21	(25)
Net change due to financing activities			1,281	(1,813)	(838)
Net change in cash and cash equivalents			(206)	1,043	(445)
Cash and cash equivalents at beginning of period			2,864	1,821	2,266
Cash and cash equivalents at end of period		$ 2,658	$ 2,658	$ 2,864	$ 1,821

[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