Securities financing activities - Schedule of securities sold under repurchase agreements & securities loaned collateral netting (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Securities sold under repurchase agreements with an appropriate legal opinion:
Net liability balance	$ 150,368	$ 147,810
Amounts not nettable on the Consolidated balance sheets, Financial Instruments	(146,749)	(145,732)
Amounts not nettable on the Consolidated balance sheets, Cash collateral	(442)	(497)
Net amount	3,177	1,581
Securities loaned:
Net liability	20,697	25,656
Amounts not nettable on the Consolidated balance sheets, Financial Instruments	(20,553)	(25,287)
Amounts not nettable on the Consolidated balance sheets, Cash collateral	0	0
Net amount	$ 144	$ 369