Guarantees, Offsetting of Resale and Repurchase Agreements and Securities Borrowing and Lending (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities owned and pledged as collateral related to repurchase agreements not available to be repledged, Fair Value	$ 4,700	$ 6,600
Net amounts in consolidated balance sheet	88,338	79,443
Collateral received, fair value	130,700	102,300
Collateral received with the right to sell or repledge	130,700	102,300
Collateral sold or repledged	69,800	50,000
Collateral pledged, fair value	111,400	91,400
Resale and securities borrowing agreements
Gross amounts recognized	119,721	91,123
Gross amounts offset in consolidated balance sheet	(31,383)	(11,680)
Net amounts in consolidated balance sheet	88,338	79,443
Collateral not recognized in consolidated balance sheet	(88,141)	(78,837)
Net amount	197	606
Repurchase and securities lending agreements
Gross amounts recognized	109,536	89,111
Gross amounts offset in consolidated balance sheet	(31,383)	(11,680)
Net amounts in consolidated balance sheet	78,153	77,431
Collateral pledged but not netted in consolidated balance sheet	(77,796)	(77,184)
Net amount	357	247
Fed Funds Sold, Securities Purchased under Resale Agreements and Other Short-Term Investments [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Net amounts in consolidated balance sheet	67,600	58,100
Resale and securities borrowing agreements
Net amounts in consolidated balance sheet	67,600	58,100
Loans [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Net amounts in consolidated balance sheet	20,700	21,300
Resale and securities borrowing agreements
Net amounts in consolidated balance sheet	$ 20,700	$ 21,300