Fair Value (Narrative) (Details) (USD $) Share data in Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Percentage of available for sale and trading securities priced by pricing services provided by third-party vendors	81.00%
Percentage of securities priced by pricing services provided by third-party vendors	84.00%
Carrying value of equity investments carried at cost and FHLB and FRB stock	$ 1,900,000,000	$ 1,900,000,000
Transfers of Assets and Liabilities from Level 2 to Level 3	462,000,000
Transfers of Assets from Level 2 to Level 1	279,000,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Recurring Assets - Fair Value	10,889,000,000
Recurring Liabilities - Fair Value	330,000,000
Black Rock Series C Preferred Stock [Member]
Total shares accounted for relating to BlackRock Series C Preferred Stock	1.5
Total shares delivered relating to BlackRock Series C Preferred Stock	1.3
Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Residential Mortgage Loans Commitments [Member]
Recurring Assets - Fair Value	123,000,000
Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other Contracts Liabilities [Member]
Recurring Liabilities - Fair Value	77,000,000
Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest Rate Contracts [Member] | Commercial Mortgage Loans Commitments [Member] | Financial Derivative Assets [Member]
Recurring Assets - Fair Value	13,000,000
Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest Rate Contracts [Member] | Commercial Mortgage Loans Commitments [Member] | Financial Derivative Liabilities [Member]
Recurring Liabilities - Fair Value	13,000,000
Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest Rate Contracts [Member] | Interest Rate Options [Member] | Financial Derivative Assets [Member]
Recurring Assets - Fair Value	4,000,000
Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest Rate Contracts [Member] | Interest Rate Options [Member] | Financial Derivative Liabilities [Member]
Recurring Liabilities - Fair Value	3,000,000
Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other Contract [Member] | Risk Participation Agreements [Member] | Financial Derivative Assets [Member]
Recurring Assets - Fair Value	7,000,000
Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other Contract [Member] | Risk Participation Agreements [Member] | Financial Derivative Liabilities [Member]
Recurring Liabilities - Fair Value	6,000,000
Derivative [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Visa Class B Swap [Member] | Financial Derivative Liabilities [Member]
Recurring Liabilities - Fair Value	22,000,000
Loans [Member] | Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Recurring Assets - Fair Value	$ 7,000,000