Securities - Other than Temporary Impairment, Credit Losses Recognized in Earnings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
Mar. 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Held-to-maturity Securities [Member]	Jun. 30, 2014 Held-to-maturity Securities [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Credit losses at the beginning of the period				$ 63	$ 61
Increase in credit losses for which an other-than-temporary impairment was previously recognized	8	(7)	8	(5)	(7)
Ending balance of credit losses on held-to-maturity debt securities for which a portion of an other-than-temporary impairment was recognized in other comprehensive income (loss)				$ 68	$ 68

This item represents the gain (loss) realized on the sale of held-to-maturity securities disposed of during the period. Additionally, this item may include, if not separately presented, any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt securities which are being or have been recognized in earnings during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27405-111563

Name:	us-gaap_HeldToMaturitySecuritiesSoldSecurityRealizedGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration