Guarantees and Contingent Liabilities - Summary of Other Guarantees and Contingent Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Carrying Amount	$ 71
Maximum Potential Future Payments	17,781
Third-Party Borrowing Arrangements [Member]
Guarantor Obligations [Line Items]
Maximum Potential Future Payments	22
Securities Lending Indemnifications [Member]
Guarantor Obligations [Line Items]
Collateral Held	4,811
Maximum Potential Future Payments	4,654
Asset Sales [Member]
Guarantor Obligations [Line Items]
Carrying Amount	281
Maximum Potential Future Payments	3,163
Merchant Processing [Member]
Guarantor Obligations [Line Items]
Collateral Held	912
Carrying Amount	81
Maximum Potential Future Payments	85,940
Contingent Consideration Arrangements [Member]
Guarantor Obligations [Line Items]
Carrying Amount	12
Maximum Potential Future Payments	14
Tender Option Bond Program Guarantee [Member]
Guarantor Obligations [Line Items]
Collateral Held	4,876
Maximum Potential Future Payments	4,755
Minimum Revenue Guarantees [Member]
Guarantor Obligations [Line Items]
Carrying Amount	13
Maximum Potential Future Payments	14
Other [Member]
Guarantor Obligations [Line Items]
Carrying Amount	6
Maximum Potential Future Payments	$ 527