Interest income and interest expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Interest income
Loans	$ 8,433	$ 8,060	$ 24,459	$ 24,138
Taxable securities	1,553	1,903	4,885	5,743
Non-taxable securities	439	387	1,260	1,041
Total securities	1,992	2,290	6,145	6,784
Trading assets	1,538	1,855	5,008	5,453
Federal funds sold and securities purchased under resale agreements	431	400	1,167	1,234
Securities borrowed	(118)	(150)	(397)	(369)
Deposits with banks	291	300	944	835
Other assets	172	171	492	505
Total interest income	12,739	12,926	37,818	38,580
Interest expense
Interest-bearing deposits	293	399	965	1,242
Short-term and other liabilities	315	238	991	1,121
Long-term debt	1,092	1,084	3,254	3,337
Beneficial interests issued by consolidated VIEs	115	98	323	308
Total interest expense	1,815	1,819	5,533	6,008
Net interest income	10,924	11,107	32,285	32,572
Provision for credit losses	682	757	2,576	2,299
Net interest income after provision for credit losses	$ 10,242	$ 10,350	$ 29,709	$ 30,273