Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Held-to-maturity securities fair value	$ 7,680	$ 8,056
Financing receivable, unearned income	$ 323	$ 356
Common shares, par value (in usd per share)	$ 1	$ 1
Common shares, shares authorized (in shares)	2,100,000,000	2,100,000,000
Common shares, shares issued (in shares)	1,256,702,081	1,256,702,081
Treasury stock, shares (in shares)	313,926,505	320,138,094
Residential Mortgage
Loans held for sale	$ 73	$ 51