Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Held-to-maturity securities, fair value	$ 5,003	$ 4,974	$ 4,733
Unearned income on loans	665	682	776
Consolidated guaranteed funds VIEs, for accrued income and other assets	1
Loan securitization trust VIEs	187
Aggregate amount of certificates of deposit, denominations	$ 100,000	$ 100,000	$ 100,000
Preferred stock, par value	$ 1	$ 1	$ 1
Preferred stock, shares authorized	25,000,000	25,000,000	25,000,000
Common shares, par value	$ 1	$ 1	$ 1
Common shares, shares authorized	1,400,000,000	1,400,000,000	1,400,000,000
Common shares, shares issued	1,016,969,905	1,016,969,905	1,016,969,905
Treasury stock, shares	166,049,974	157,566,493	132,100,665
Series A Preferred Stock [Member]
Preferred stock, liquidation preference	$ 100	$ 100	$ 100
Preferred stock, shares authorized	7,475,000	7,475,000	7,475,000
Preferred stock, shares issued, Total	2,900,234	2,904,839	2,904,839
Preferred stock, dividend rate	7.75%	7.75%	7.75%