Contingent Liabilities and Guarantees - Guarantees (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	$ 14,220
Liability Recorded	145
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	10,764
Liability Recorded	79
Recourse Agreement with FNMA [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	1,247
Liability Recorded	6
Return Guarantee Agreement with LIHTC Investors [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	17
Liability Recorded	17
Written Put Options [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	2,192
Liability Recorded	43
Default Guarantees [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments
Liability Recorded