Securities Financing Activities - Schedule of securities purchased under resale agreements, netting & securities borrowed (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Securities purchased under resale agreements:
Securities purchased under resale agreements with an appropriate legal opinion	$ 375,619	$ 347,142
Amounts netted on the Consolidated balance sheets	(166,295)	(142,719)
Securities purchased under resale agreements with an appropriate legal opinion, Net asset balance	209,324	204,423
Securities purchased under resale agreements where an appropriate legal opinion has not been either sought or obtained	2,745	10,598
Total securities purchased under resale agreements, gross asset balance	378,364	357,740
Total securities purchased under resale agreements, net asset balance	212,069	215,021
Securities borrowed	98,528	110,435
Securities borrowed where an appropriate legal opinion has not been either sought or obtained	19,200	27,700
Securities Financing Transaction, Fair Value
Securities purchased under resale agreements:
Total securities purchased under resale agreements, net asset balance	28,700	28,600
Securities borrowed, fair value	$ 495	$ 992