Securities Financing Activities - Schedule of securities purchased under resale agreements, netting & securities borrowed (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Securities purchased under resale agreements:
Securities purchased under resale agreements with an appropriate legal opinion, Gross asset balance	$ 365,805	$ 347,142
Amounts netted on the Consolidated Balance Sheets	(156,258)	(142,719)
Securities purchased under resale agreements with an appropriate legal opinion, Net asset balance	209,547	204,423
Securities purchased under resale agreements where an appropriate legal opinion has not been either sought or obtained	2,343	10,598
Total securities purchased under resale agreements, gross asset balance	368,148	357,740
Total securities purchased under resale agreements, net asset balance	211,890	215,021
Securities borrowed	98,721	110,435
Securities borrowed where an appropriate legal opinion has not been either sought or obtained	31,300	35,300
Securities Financing Transaction, Fair Value
Securities purchased under resale agreements:
Total securities purchased under resale agreements, net asset balance	23,100	28,600
Securities borrowed, fair value	$ 395	$ 992