Guarantees and Contingent Liabilities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Summary of other guarantees and contingent liabilities
Carrying Amount	$ 425	$ 359
Standby Letters of Credit [Member]
Summary of other guarantees and contingent liabilities
Carrying Amount	87
Maximum Potential Future Payments	18,896
Third party borrowing arrangements [Member]
Summary of other guarantees and contingent liabilities
Maximum Potential Future Payments	335
Securities lending indemnifications [Member]
Summary of other guarantees and contingent liabilities
Collateral Held	8,780
Maximum Potential Future Payments	8,653
Asset sales [Member]
Summary of other guarantees and contingent liabilities
Carrying Amount	297
Maximum Potential Future Payments	2,554
Merchant processing [Member]
Summary of other guarantees and contingent liabilities
Collateral Held	822
Carrying Amount	87
Maximum Potential Future Payments	83,527
Contingent consideration arrangements [Member]
Summary of other guarantees and contingent liabilities
Carrying Amount	3
Maximum Potential Future Payments	6
Tender option bond program guarantee [Member]
Summary of other guarantees and contingent liabilities
Collateral Held	5,389
Maximum Potential Future Payments	5,167
Minimum revenue guarantees [Member]
Summary of other guarantees and contingent liabilities
Carrying Amount	19
Maximum Potential Future Payments	31
Other [Member]
Summary of other guarantees and contingent liabilities
Carrying Amount	19
Maximum Potential Future Payments	$ 3,483