Consolidated Balance Sheets (Parenthetical) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Fair Value	$ 8,842,000,000	$ 10,116,000,000
Unearned income on loans	481,000,000	603,000,000
Loans held for sale		0
Aggregate amount of certificates of deposit, denominations	$ 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)	280,497,287	279,513,530
Residential Mortgage
Loans held for sale	$ 288,000,000	$ 140,000,000