Securities - Securities Impairment (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Held-to-maturity Securities, Fair Value:
Less than 12 months	$ 998	$ 20,745
12 months or more	0	0
Total fair value	998	20,745
Held-to-maturity Securities, Aggregate Loss:
Less than 12 months	2	317
12 months or more	0	0
Total gross unrealized losses	2	317
Investment Securities, Fair Value:
Less than 12 months	32,934	101,248
12 months or more	18,602	3,319
Total fair value	51,536	104,567
Investment Securities, Aggregate Loss:
Less than 12 months	129	2,755
12 months or more	309	178
Total gross unrealized losses	438	2,933
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Available-for-sale Securities, Fair Value:
Less than 12 months	5,942	20,293
12 months or more	6,711	1,150
Total fair value	12,653	21,443
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	21	895
12 months or more	179	82
Total gross unrealized losses	200	977
Prime and Alt-A | Residential and commercial mortgage securitizations
Available-for-sale Securities, Fair Value:
Less than 12 months	925	1,061
12 months or more	429	0
Total fair value	1,354	1,061
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	3	27
12 months or more	25	0
Total gross unrealized losses	28	27
Subprime | Residential and commercial mortgage securitizations
Available-for-sale Securities, Fair Value:
Less than 12 months	0	152
12 months or more	0	0
Total fair value	0	152
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	0	1
12 months or more	0	0
Total gross unrealized losses	0	1
Non-U.S. | Residential and commercial mortgage securitizations
Available-for-sale Securities, Fair Value:
Less than 12 months	0	0
12 months or more	0	158
Total fair value	0	158
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	0	0
12 months or more	0	1
Total gross unrealized losses	0	1
Commercial
Available-for-sale Securities, Fair Value:
Less than 12 months	2,236	3,980
12 months or more	282	0
Total fair value	2,518	3,980
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	9	26
12 months or more	3	0
Total gross unrealized losses	12	26
Total mortgage-backed securities
Available-for-sale Securities, Fair Value:
Less than 12 months	9,103	25,486
12 months or more	7,422	1,308
Total fair value	16,525	26,794
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	33	949
12 months or more	207	83
Total gross unrealized losses	240	1,032
U.S. Treasury and government agencies
Available-for-sale Securities, Fair Value:
Less than 12 months	502	6,293
12 months or more	1,994	237
Total fair value	2,496	6,530
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	1	250
12 months or more	2	56
Total gross unrealized losses	3	306
Obligations of U.S. states and municipalities
Available-for-sale Securities, Fair Value:
Less than 12 months	2,660	15,387
12 months or more	163	55
Total fair value	2,823	15,442
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	34	975
12 months or more	4	12
Total gross unrealized losses	38	987
Certificates of deposit
Available-for-sale Securities, Fair Value:
Less than 12 months	1,256	988
12 months or more	0	0
Total fair value	1,256	988
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	2	1
12 months or more	0	0
Total gross unrealized losses	2	1
Non-U.S. government debt securities
Available-for-sale Securities, Fair Value:
Less than 12 months	6,037	11,286
12 months or more	1,185	821
Total fair value	7,222	12,107
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	10	110
12 months or more	25	12
Total gross unrealized losses	35	122
Corporate debt securities
Available-for-sale Securities, Fair Value:
Less than 12 months	2,001	1,580
12 months or more	321	505
Total fair value	2,322	2,085
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	9	21
12 months or more	4	8
Total gross unrealized losses	13	29
Asset-backed securities - Collateralized loan obligations
Available-for-sale Securities, Fair Value:
Less than 12 months	9,996	18,369
12 months or more	7,517	393
Total fair value	17,513	18,762
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	35	129
12 months or more	67	7
Total gross unrealized losses	102	136
Other Debt Obligations
Available-for-sale Securities, Fair Value:
Less than 12 months	381	1,114
12 months or more	0	0
Total fair value	381	1,114
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	3	3
12 months or more	0	0
Total gross unrealized losses	3	3
Debt Securities
Available-for-sale Securities, Fair Value:
Less than 12 months	31,936	80,503
12 months or more	18,602	3,319
Total fair value	50,538	83,822
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	127	2,438
12 months or more	309	178
Total gross unrealized losses	436	2,616
Equity securities
Available-for-sale Securities, Fair Value:
Less than 12 months	0	0
12 months or more	0	0
Total fair value	0	0
Available-for-sale Securities, Aggregate Loss:
Less than 12 months	0	0
12 months or more	0	0
Total gross unrealized losses	$ 0	$ 0