Parent Company Financial Statements - Statement of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Activities:
Net cash provided by (used in) operating activities	$ 11,954	$ (6,710)	$ 3,532
Investing Activities:
Net decrease (increase) in interest-bearing deposits with consolidated banking subsidiary	4,765	10,602	(47,995)
Purchases of available-for-sale securities	(18,029)	(53,750)	(37,873)
Net cash provided by (used in) investing activities	6,816	(2,172)	(65,534)
Financing Activities:
Proceeds from issuance of long-term debt, net of issuance costs	3,731	1,343	2,489
Payments for long-term debt	(1,567)	(1,443)	(1,724)
Payments for redemption of preferred stock	0	(500)	(500)
Proceeds from issuance of common stock, net of issuance costs	0	1,900	0
Repurchases of common stock	(1,500)	(900)	(515)
Repurchases of common stock for employee tax withholding	(123)	(39)	(78)
Payments for cash dividends	(972)	(866)	(889)
Net cash (used in) provided by financing activities	(18,431)	9,046	62,167
Net increase	339	164	165
Cash and due from banks at beginning of period	3,631	3,467	3,302
Cash and due from banks at end of period	3,970	3,631	3,467
Parent Company
Operating Activities:
Net cash provided by (used in) operating activities	1,608	(116)	3,513
Investing Activities:
Net decrease (increase) in interest-bearing deposits with consolidated banking subsidiary	22	10	(64)
Proceeds from sales and maturities of available-for-sale securities	780	525	1,000
Purchases of available-for-sale securities	(886)	(575)	(849)
Investments in consolidated banking and non-banking subsidiaries	(16,252)	(6,288)	(7,406)
Sale or repayment of investment in consolidated banking and non-banking subsidiaries	15,092	7,006	4,999
Net cash provided by (used in) investing activities	(1,244)	678	(2,320)
Financing Activities:
Proceeds from issuance of long-term debt, net of issuance costs	3,731	1,343	2,489
Payments for long-term debt	(1,500)	(1,500)	(1,700)
Payments for redemption of preferred stock	0	(500)	(500)
Proceeds from issuance of common stock, net of issuance costs	0	1,900	0
Repurchases of common stock	(1,500)	(900)	(515)
Repurchases of common stock for employee tax withholding	(123)	(39)	(78)
Payments for cash dividends	(972)	(866)	(889)
Net cash (used in) provided by financing activities	(364)	(562)	(1,193)
Net increase	0	0	0
Cash and due from banks at beginning of period	0	0	0
Cash and due from banks at end of period	$ 0	$ 0	$ 0