Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Held-to-maturity securities, fair value	$ 3,779	$ 3,992	$ 3,052
Unearned income on loans	923	957	1,282
Consolidated guaranteed funds VIEs, for accrued income and other assets	50
Consolidated education loan securitization trust VIEs at fair value, Discontinued assets	2,358
Loans in portfolio at fair value, Discontinued assets	154
Aggregate amount of certificates of deposit	$100,000 or more	$100,000 or more	$100,000 or more
Consolidated education loan securitization trust VIEs at fair value, Discontinued liabilities	$ 2,151
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	94,388,605	91,201,285	60,868,267
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	2,904,839	2,904,839	2,904,839
Preferred stock, dividend rate	7.75%	7.75%	7.75%