Securities Financing Activities - Types of Financial Assets Pledged and Remaining Maturity (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	$ 472,560	$ 398,218
Securities loaned and other	38,720	27,228
Lending transactions	17,510	18,414
Securities-for-securities
Securities Financing Transaction [Line Items]
Lending transactions	5,200	9,200
Overnight and continuous
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	195,713	142,185
Securities loaned and other	29,415	22,876
Up to 30 days
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	166,754	180,674
Securities loaned and other	138	375
30 – 90 days
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	46,511	41,611
Securities loaned and other	1,805	2,328
Greater than 90 days
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	63,582	33,748
Securities loaned and other	7,362	1,649
Mortgage-backed securities, U.S. government agencies
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	25,116	13,100
Securities loaned and other	0	0
Mortgage-backed securities, Residential - nonagency
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	1,861	2,972
Securities loaned and other	0	0
Mortgage-backed securities, Commercial - nonagency
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	1,431	1,594
Securities loaned and other	0	0
U.S. Treasury and government agencies
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	236,939	177,581
Securities loaned and other	14	14
Obligations of U.S. states and municipalities
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	1,161	1,557
Securities loaned and other	0	0
Non-U.S. government debt
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	174,400	170,196
Securities loaned and other	2,294	2,485
Corporate debt securities
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	15,474	14,231
Securities loaned and other	216	287
Asset-backed securities
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	2,543	3,508
Securities loaned and other	0	0
Equity securities
Securities Financing Transaction [Line Items]
Securities sold under repurchase agreements	13,635	13,479
Securities loaned and other	$ 36,196	$ 24,442

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Amount, after the effects of master netting arrangements, of securities loaned to entities in exchange for collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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