Securities - Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Held-to-maturity Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	$ 0	$ 3,763
Less than 12 months, Gross unrealized losses	0	46
12 months or more, Fair value	0	0
12 months or more, Gross unrealized losses	0	0
Total fair value	0	3,763
Total gross unrealized losses	0	46
Investment Securities, Continuous Unrealized Loss Position
Less than 12 months, Fair value	56,422	76,475
Less than 12 months, Gross unrealized losses	802	905
12 months or more, Fair value	15,887	14,877
12 months or more, Gross unrealized losses	298	251
Total fair value	72,309	91,352
Total gross unrealized losses	1,100	1,156
Debt securities
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	56,422	72,712
Less than 12 months, Gross unrealized losses	802	859
12 months or more, Fair Value	15,887	14,877
12 months or more, Gross unrealized losses	298	251
Total fair value	72,309	87,589
Total gross unrealized losses	1,100	1,110
Total mortgage-backed securities
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	18,317	33,949
Less than 12 months, Gross unrealized losses	278	397
12 months or more, Fair Value	3,081	1,760
12 months or more, Gross unrealized losses	56	22
Total fair value	21,398	35,709
Total gross unrealized losses	334	419
U.S. government agencies
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	1,706	13,002
Less than 12 months, Gross unrealized losses	8	95
12 months or more, Fair Value	873	697
12 months or more, Gross unrealized losses	18	11
Total fair value	2,579	13,699
Total gross unrealized losses	26	106
Residential: Prime and Alt-A | Residential mortgage-backed securities
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	3,049	5,147
Less than 12 months, Gross unrealized losses	27	51
12 months or more, Fair Value	399	238
12 months or more, Gross unrealized losses	13	6
Total fair value	3,448	5,385
Total gross unrealized losses	40	57
Residential: Subprime | Residential mortgage-backed securities
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	0	0
Less than 12 months, Gross unrealized losses	0	0
12 months or more, Fair Value	0	0
12 months or more, Gross unrealized losses	0	0
Total fair value	0	0
Total gross unrealized losses	0	0
Residential: Non-U.S. | Residential mortgage-backed securities
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	2,263	2,021
Less than 12 months, Gross unrealized losses	17	12
12 months or more, Fair Value	380	167
12 months or more, Gross unrealized losses	4	1
Total fair value	2,643	2,188
Total gross unrealized losses	21	13
Commercial
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	11,299	13,779
Less than 12 months, Gross unrealized losses	226	239
12 months or more, Fair Value	1,429	658
12 months or more, Gross unrealized losses	21	4
Total fair value	12,728	14,437
Total gross unrealized losses	247	243
U.S. Treasury and government agencies
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	11,435	10,998
Less than 12 months, Gross unrealized losses	199	166
12 months or more, Fair Value	0	0
12 months or more, Gross unrealized losses	0	0
Total fair value	11,435	10,998
Total gross unrealized losses	199	166
Obligations of U.S. states and municipalities
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	700	1,676
Less than 12 months, Gross unrealized losses	16	18
12 months or more, Fair Value	261	205
12 months or more, Gross unrealized losses	3	5
Total fair value	961	1,881
Total gross unrealized losses	19	23
Certificates of deposit
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	0	0
Less than 12 months, Gross unrealized losses	0	0
12 months or more, Fair Value	0	0
12 months or more, Gross unrealized losses	0	0
Total fair value	0	0
Total gross unrealized losses	0	0
Non-U.S. government debt securities
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	2,490	3,267
Less than 12 months, Gross unrealized losses	37	26
12 months or more, Fair Value	262	367
12 months or more, Gross unrealized losses	2	15
Total fair value	2,752	3,634
Total gross unrealized losses	39	41
Corporate debt securities
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	2,179	3,198
Less than 12 months, Gross unrealized losses	86	125
12 months or more, Fair Value	587	848
12 months or more, Gross unrealized losses	35	45
Total fair value	2,766	4,046
Total gross unrealized losses	121	170
Asset-backed securities: Collateralized loan obligations
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	17,175	15,340
Less than 12 months, Gross unrealized losses	110	67
12 months or more, Fair Value	10,725	10,692
12 months or more, Gross unrealized losses	162	124
Total fair value	27,900	26,032
Total gross unrealized losses	272	191
Asset-backed securities: Other
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	4,126	4,284
Less than 12 months, Gross unrealized losses	76	60
12 months or more, Fair Value	971	1,005
12 months or more, Gross unrealized losses	40	40
Total fair value	5,097	5,289
Total gross unrealized losses	116	100
Available-for-sale equity securities
Available-for-sale Securities, Securities with Gross Unrealized Losses
Less than 12 months, Fair value	0	0
Less than 12 months, Gross unrealized losses	0	0
12 months or more, Fair Value	0	0
12 months or more, Gross unrealized losses	0	0
Total fair value	0	0
Total gross unrealized losses	$ 0	$ 0