Consolidated Balance Sheets (Parenthetical) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Fair Value	$ 8,664,000,000	$ 8,023,000,000
Financing Receivable, Deferred Commitment Fee	361,000,000	449,000,000
Aggregate Amount Of Certificates Of Deposit	$ 100,000	$ 100,000
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)	326,158,458	280,928,782
Residential Mortgage
Loans held for sale	$ 237,000,000	$ 264,000,000