Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk Level 4 - Derivatives Volume (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Jun. 30, 2012	Sep. 30, 2011
Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk [Abstract]
Notional Amount of Interest Rate Derivatives	$ 765
Derivative, Average Remaining Maturity	9 months
Derivative, Number of Instruments Held	3,900,000	3,900,000

Aggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

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