Parent Company Financial Statements Parent Company Financial Statements (Balance Sheets) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Cash and due from subsidiary banks	$ 1,758	$ 1,236
Other short-term investments	157	197
Premises and equipment	400	454
Accrued income and other assets	6,763	5,603
Total assets	85,406	94,616
Total medium- and long-term debt	3,024	2,796
Accrued expenses and other liabilities	2,593	1,584
Total liabilities	$ 80,225	$ 86,719
Preferred Stock, No Par Value	$ 0	$ 0
Preferred Stock, Shares Authorized	4,000	4,000
Preferred Stock, Shares Issued	4,000	4,000
Fixed rate reset non-cumulative perpetual preferred stock, series A, no par value, $100,000 liquidation preference per share: Authorized - 4,000 shares, Issued - 4,000 shares at 12/31/2022 and 12/31/2021	$ 394	$ 394
Common stock, par value	$ 5	$ 5
Common stock, authorized shares	325,000,000	325,000,000
Common stock, issued shares	228,164,824	228,164,824
Common stock - $5 par value: Authorized - 325,000,000 shares; Issued - 228,164,824 shares	$ 1,141	$ 1,141
Capital surplus	2,220	2,175
Accumulated other comprehensive loss	(3,742)	(212)	$ 64
Retained earnings	$ 11,258	$ 10,494
Shares in treasury	97,197,962	97,476,872
Less cost of common stock in treasury - 97,197,962 shares at 12/31/22 and 97,476,872 shares at 12/31/21	$ (6,090)	$ (6,095)
Total shareholders' equity	5,181	7,897	$ 8,050	$ 7,327
Total liabilities and shareholders' equity	85,406	94,616
Parent Company
Condensed Financial Statements, Captions [Line Items]
Cash and due from subsidiary banks	1,810	1,105
Other short-term investments	92	113
Receivable due from subsidiary bank	150	150
Investments in subsidiaries, principally banks	4,853	8,278
Premises and equipment	0	1
Accrued income and other assets	191	265
Total assets	7,096	9,912
Total medium- and long-term debt	1,593	1,736
Accrued expenses and other liabilities	322	279
Total liabilities	1,915	2,015
Total liabilities and shareholders' equity	$ 7,096	$ 9,912