Interest income and interest expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Interest income
Loans	$ 8,079	$ 8,039	$ 16,026	$ 16,078
Taxable securities	1,608	1,940	3,332	3,840
Non-taxable securities	423	337	821	654
Total securities	2,031	2,277	4,153	4,494
Trading assets	1,736	1,827	3,470	3,598
Federal funds sold and securities purchased under resale agreements	340	398	736	834
Securities borrowed	(159)	(131)	(279)	(219)
Deposits with banks	312	279	653	535
Other assets	175	172	320	334
Total interest income	12,514	12,861	25,079	25,654
Interest expense
Interest-bearing deposits	308	417	672	843
Short-term and other liabilities	344	455	676	883
Long-term debt	1,068	1,086	2,162	2,253
Beneficial interests issued by consolidated VIEs	110	105	208	210
Total interest expense	1,830	2,063	3,718	4,189
Net interest income	10,684	10,798	21,361	21,465
Provision for credit losses	935	692	1,894	1,542
Net interest income after provision for credit losses	$ 9,749	$ 10,106	$ 19,467	$ 19,923