Financial Derivatives (Derivative Assets and Liabilitites Offsetting) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	$ 4,851	$ 5,234
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	3,827	4,027
Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	3,827	4,027
Derivative Liability, Fair Value Offset Amount	1,945	2,141
Derivative Liability, Cash Collateral	491	503
Derivative Liability, Net Fair Value	1,391	1,383
Derivative Liability, Net	1,391	1,383
Exchange Cleared [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	725	657
Assets [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	4,851	5,234
Derivative Asset, Fair Value Offset Amount	1,945	2,141
Derivative Asset, Cash Collateral	349	506
Derivative Asset, Net Fair Value	2,557	2,587
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	133	144
Derivative Asset, Net	2,424	2,443
Exchange Cleared [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	889	807
Interest Rate Contracts [Member] | Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	3,112	3,272
Derivative Liability, Fair Value Offset Amount	1,856	2,057
Derivative Liability, Cash Collateral	470	483
Derivative Liability, Net Fair Value	786	732
Derivative Liability, Net	786	732
Interest Rate Contracts [Member] | Assets [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	4,599	4,918
Derivative Asset, Fair Value Offset Amount	1,806	1,981
Derivative Asset, Cash Collateral	337	458
Derivative Asset, Net Fair Value	2,456	2,479
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	130	143
Derivative Asset, Net	2,326	2,336
Foreign Exchange Contract [Member] | Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	225	241
Derivative Liability, Fair Value Offset Amount	85	80
Derivative Liability, Cash Collateral	20	20
Derivative Liability, Net Fair Value	120	141
Derivative Liability, Net	120	141
Foreign Exchange Contract [Member] | Assets [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	250	314
Derivative Asset, Fair Value Offset Amount	138	159
Derivative Asset, Cash Collateral	11	47
Derivative Asset, Net Fair Value	101	108
Derivative Asset, Securities Collateral Held Under Master Netting Agreements	3	1
Derivative Asset, Net	98	107
Credit Risk Contract [Member] | Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	5	4
Derivative Liability, Fair Value Offset Amount	4	4
Derivative Liability, Cash Collateral	1
Credit Risk Contract [Member] | Assets [Member]
Offsetting Assets [Line Items]
Derivative Asset, Gross Fair Value	2	2
Derivative Asset, Fair Value Offset Amount	1	1
Derivative Asset, Cash Collateral	1	1
Other Contract [Member] | Liability [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Gross Fair Value	485	510
Derivative Liability, Net Fair Value	485	510
Derivative Liability, Net	$ 485	$ 510