Fair Value (Fair Value Option Gains Losses for Mortgage Loans Held-for-Sale) (Details) (Residential Loans [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Residential Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Instrument-specific credit risk based on changes in credit spreads for non-agency loans and adjustments in individual loan quality	$ (1)	$ (2)
Other changes in estimated fair value	0	170
Total gains (losses) recognized in other revenues	$ (1)	$ 168

This item represents the estimated amount of gains or losses included in earnings during the period attributable to changes in instrument-specific credit risk arising from loans and other receivables held as assets.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 30

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 19

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_FairValueOptionCreditRiskGainsLossesOnAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration