Financial Derivatives (Derivative Assets and Liabilitites Offsetting) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	$ 6,585	$ 8,568
Derivative Asset, Securities Collateral Held Under Master Netting Agreements
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	5,330	6,610
Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	5,330	6,610
Derivative Liability, Fair Value Offset Amount	3,683	5,107
Derivative Liability, Cash Collateral	582	914
Derivative Liability, Net Fair Value	1,065	589
Derivative Liability, Securities Collateral Pledged Under Master Netting Agreements		18
Derivative Liability, Net	1,065	571
Assets [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	6,585	8,568
Derivative Asset, Fair Value Offset Amount	3,683	5,107
Derivative Asset, Cash Collateral	658	1,031
Derivative Asset, Net Fair Value	2,244	2,430
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	233	135
Derivative Asset, Net	2,011	2,295
Interest Rate Contracts [Member] | Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	4,831	6,118
Derivative Liability, Fair Value Offset Amount	3,625	5,060
Derivative Liability, Cash Collateral	573	908
Derivative Liability, Net Fair Value	633	150
Derivative Liability, Securities Collateral Pledged Under Master Netting Agreements		18
Derivative Liability, Net	633	132
Interest Rate Contracts [Member] | Assets [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	6,325	8,432
Derivative Asset, Fair Value Offset Amount	3,534	5,041
Derivative Asset, Cash Collateral	635	1,024
Derivative Asset, Net Fair Value	2,156	2,367
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	233	135
Derivative Asset, Net	1,923	2,232
Foreign Exchange Contract [Member] | Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	164	123
Derivative Liability, Fair Value Offset Amount	55	47
Derivative Liability, Cash Collateral	9	6
Derivative Liability, Net Fair Value	100	70
Derivative Liability, Securities Collateral Pledged Under Master Netting Agreements
Derivative Liability, Net	100	70
Foreign Exchange Contract [Member] | Assets [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	257	126
Derivative Asset, Fair Value Offset Amount	146	61
Derivative Asset, Cash Collateral	23	7
Derivative Asset, Net Fair Value	88	58
Derivative Asset, Securities Collateral Held Under Master Netting Agreements
Derivative Asset, Net	88	58
Equity Contract [Member] | Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	0	5
Derivative Liability, Fair Value Offset Amount
Derivative Liability, Cash Collateral
Derivative Liability, Net Fair Value	0	5
Derivative Liability, Securities Collateral Pledged Under Master Netting Agreements
Derivative Liability, Net	0	5
Equity Contract [Member] | Assets [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	0	3
Derivative Asset, Fair Value Offset Amount	0	3
Derivative Asset, Cash Collateral
Derivative Asset, Net Fair Value
Derivative Asset, Net
Credit Risk Contract [Member] | Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	4	6
Derivative Liability, Fair Value Offset Amount	3
Derivative Liability, Cash Collateral
Derivative Liability, Net Fair Value	1	6
Derivative Liability, Securities Collateral Pledged Under Master Netting Agreements
Derivative Liability, Net	1	6
Credit Risk Contract [Member] | Assets [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	3	7
Derivative Asset, Fair Value Offset Amount	3	2
Derivative Asset, Cash Collateral
Derivative Asset, Net Fair Value		5
Derivative Asset, Securities Collateral Held Under Master Netting Agreements
Derivative Asset, Net		5
Other Contract [Member] | Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	331	358
Derivative Liability, Fair Value Offset Amount
Derivative Liability, Cash Collateral
Derivative Liability, Net Fair Value	331	358
Derivative Liability, Securities Collateral Pledged Under Master Netting Agreements
Derivative Liability, Net	$ 331	$ 358