Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Low Income Housing Limited Liability Partnership
Interest bearing deposits with banks	$ 18,809	[1]	$ 25,454	[1]
Other assets	7,967	[1]	6,369	[1]
Long-term debt	20,014	[1]	16,709	[1]
Variable interest entities [Member]
Low Income Housing Limited Liability Partnership
Interest bearing deposits with banks	110		108
Other assets	535		520
Long-term debt	55		55
Other Liabilities, Noncurrent	195		166
Low Income Housing Limited Asset Partnership	645		628
Low Income Housing Limited Liability Partnership, Total	$ 250		$ 221

[1] The following table summarizes assets and liabilities related to variable interest entities ("VIEs") as of June 30, 2012 and December 31, 2011 which are consolidated on our balance sheet. Assets and liabilities exclude intercompany balances that eliminate in consolidation.