Deposits (Details 2) (USD $) In Billions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deposits
Aggregate amount of certificates of deposit greater than $100,000	$ 1.25	$ 1.73

The aggregate amount of domestic time deposits (including certificates of deposits, individual retirement accounts and open accounts) in denominations of $100,000 or more.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6479006&loc=d3e64164-112818

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 14

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_TimeDeposits100000OrMoreDomestic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant