CONDENSED PARENT COMPANY FINANCIAL STATEMENTS - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities of continuing operations	$ (73,416)	$ 25,069	$ 47,090
Cash flows from investing activities of continuing operations
Net cash provided by (used in) investing activities of continuing operations	(8,459)	(79,455)	(110,746)
Cash flows from financing activities of continuing operations
Dividends paid	(5,212)	(5,003)	(5,198)
Issuance of preferred stock	2,739	0	3,300
Redemption of preferred stock	(4,145)	0	(3,785)
Treasury stock acquired	(1,977)	(3,250)	(7,601)
Net cash provided by financing activities of continuing operations	687	137,763	17,272
Change in cash, due from banks and deposits with banks	(81,093)	79,992	(47,582)
Cash, due from banks and deposits with banks at beginning of year	342,025	262,033	309,615
Cash, due from banks and deposits with banks at end of year	260,932	342,025	262,033
Cash and due from banks (including segregated cash and other deposits)	27,342	30,577	27,515
Deposits with banks, net of allowance	233,590	311,448	234,518
Cash, due from banks and deposits with banks at end of year	260,932	342,025	262,033
Supplemental disclosure of cash flow information for continuing operations
Cash paid during the year for income taxes	5,727	3,733	4,028
Cash paid during the year for interest	72,989	22,615	7,143
Parent Company
Condensed Cash Flow Statements, Captions [Line Items]
Net cash provided by operating activities of continuing operations	17,163	156	3,947
Cash flows from investing activities of continuing operations
Changes in investments and advances—intercompany	(3,450)	(7,815)	8,260
Net cash provided by (used in) investing activities of continuing operations	(3,450)	(7,815)	8,260
Cash flows from financing activities of continuing operations
Dividends paid	(5,212)	(5,003)	(5,198)
Issuance of preferred stock	2,739	0	3,300
Redemption of preferred stock	(4,145)	0	(3,785)
Treasury stock acquired	(1,977)	(3,250)	(7,601)
Proceeds (repayments) from issuance of long-term debt, net	(6,955)	14,661	(86)
Net change in short-term borrowings and other advances—intercompany	2,162	1,093	501
Other financing activities	(329)	(344)	(337)
Net cash provided by financing activities of continuing operations	(13,717)	7,157	(13,206)
Change in cash, due from banks and deposits with banks	(4)	(502)	(999)
Cash, due from banks and deposits with banks at beginning of year	3,015	3,517	4,516
Cash, due from banks and deposits with banks at end of year	3,011	3,015	3,517
Cash and due from banks (including segregated cash and other deposits)	11	15	17
Deposits with banks, net of allowance		3,000	3,500
Cash, due from banks and deposits with banks at end of year	3,011	3,015	3,517
Supplemental disclosure of cash flow information for continuing operations
Cash paid during the year for income taxes	(2,000)	(1,269)	(2,406)
Cash paid during the year for interest	$ 5,704	$ 1,309	$ (3,101)