Collateralized Transactions (Balance Sheet Offsetting) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Securities Purchased under Agreements to Resell
Gross amount	$ 185,825	$ 148,234
Amounts offset in the Condensed Consolidated Statements of Financial Condition	(58,619)	(64,946)
Net amount presented in the Condensed Consolidated Statements of Financial Condition	127,206	83,288
Financial instruments not offset in the Condensed Consolidated Statements of Financial Condition	(122,156)	(79,343)
Net exposure	5,050	3,945
Securities Borrowed
Gross amount	157,456	145,556
Amounts offset in the Condensed Consolidated Statements of Financial Condition	(9,211)	(8,848)
Net amount presented in the Condensed Consolidated Statements of Financial Condition	148,245	136,708
Financial instruments not offset in the Condensed Consolidated Statements of Financial Condition	(141,809)	(128,282)
Net exposure	6,436	8,426
Securities Sold under Agreements to Repurchase
Gross amount	117,189	134,895
Amounts offset in the Condensed Consolidated Statements of Financial Condition	(58,619)	(64,946)
Net amount presented in the Condensed Consolidated Statements of Financial Condition	58,570	69,949
Financial instruments not offset in the Condensed Consolidated Statements of Financial Condition	(48,777)	(56,454)
Net exposure	9,793	13,495
Securities Loaned
Gross amount	29,855	34,067
Amounts offset in the Condensed Consolidated Statements of Financial Condition	(9,211)	(8,848)
Net amount presented in the Condensed Consolidated Statements of Financial Condition	20,644	25,219
Financial instruments not offset in the Condensed Consolidated Statements of Financial Condition	(20,183)	(24,252)
Net exposure	461	967
Securities purchased under agreements to resell, which are either not subject to master netting agreements or are subject to such agreements but the entity has not determined the agreements to be legally enforceable	4,900	3,900
Securities borrowed, which are either not subject to master netting agreements or are subject to such agreements but the entity has not determined the agreements to be legally enforceable	3,500	4,200
Securities sold under agreements to repurchase, which are either not subject to master netting agreements or are subject to such agreements but the entity has not determined the agreements to be legally enforceable	9,700	15,600
Securities loaned, which are either not subject to master netting agreements or are subject to such agreements but the entity has not determined the agreements to be legally enforceable	$ 400	$ 700