Financial Instruments (Securities Repurchase and Reverse Repurchase Arrangements) (Details) (USD $)	3 Months Ended
Mar. 31, 2013
Derivative Instrument Detail [Abstract]
Securities For Repurchase Agreements	$ 71,000,000
Reverse Repurchase Agreements Maturities	90
Securities for Reverse Repurchase Agreements	$ 20,900,000,000

The carrying value of securities purchased to be resold in reverse repurchase transactions as of the balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(m)(2)(i))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Name:	us-gaap_SecuritiesForReverseRepurchaseAgreements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant