Consolidated Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Fair Value	$ 7,665,000,000	$ 8,023,000,000
Unearned income on loans	373,000,000	449,000,000
Certificate of deposit ($100,000 or more)	$ 100,000	$ 100,000
Common shares, par value (in dollars per share)	$ 1	$ 1
Common shares, authorized (in shares)	2,100,000,000	2,100,000,000
Common shares, issued (in shares)	1,256,702,081	1,256,702,081
Treasury stock (in shares)	327,852,311	280,928,782
Residential Mortgage
Loans held for sale	$ 281,000,000	$ 264,000,000