Asset Quality (Details 6) (USD $) In Millions	Sep. 30, 2011	Sep. 30, 2010
Consumer Credit Exposure Credit Risk Profile by Regulatory Classifications
Credit risk profile based on payment	$ 48,195
Pass [Member] | Residential, Prime, Financing Receivable [Member]
Consumer Credit Exposure Credit Risk Profile by Regulatory Classifications
Credit risk profile based on payment	11,550	11,966
Special Mention [Member] | Residential, Prime, Financing Receivable [Member]
Consumer Credit Exposure Credit Risk Profile by Regulatory Classifications
Credit risk profile based on payment	0	0
Substandard [Member] | Residential, Prime, Financing Receivable [Member]
Consumer Credit Exposure Credit Risk Profile by Regulatory Classifications
Credit risk profile based on payment	237	249
Residential, Prime, Financing Receivable [Member]
Consumer Credit Exposure Credit Risk Profile by Regulatory Classifications
Credit risk profile based on payment	$ 11,787	$ 12,215