Non-U.S. Activities (Summary Of Non-U.S. Assets) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Interest-bearing deposits with banks	$ 39,224	$ 50,763
Other assets	21,285	18,016
Total assets	218,189	222,582
Non-U.S. Assets [Member]
Segment Reporting Information [Line Items]
Interest-bearing deposits with banks	14,436	20,665
Investment securities	28,733	28,976
Other assets	8,592	5,929
Total assets	$ 51,761	$ 55,570