Consolidated Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Loans held for sale	$ 0	$ 0
Held-to-maturity securities, fair value	10,007,000,000	4,848,000,000
Unearned income on loans	826,000,000	646,000,000
Loan secularization trust VIE’s	3,000,000	4,000,000
Aggregate amount of certificates of deposit, denominations	$ 100,000	$ 100,000
Common shares, par value (in dollars per share)	$ 1	$ 1
Common shares, shares authorized (in shares)	1,400,000,000	1,400,000,000
Common shares, shares issued (in shares)	1,256,702,081	1,016,969,905
Treasury stock (in shares)	177,388,429	181,218,648
Residential Mortgage [Member]
Loans held for sale	$ 62,000,000