Guarantees, Offsetting of Resale and Repurchase Agreements and Securities Borrowing and Lending (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
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	$ 3,500	$ 4,400
Net amounts in consolidated balance sheet	130,848	97,404
Collateral received, fair value	157,400	123,100
Collateral received with the right to sell or repledge	157,400	123,100
Collateral sold or repledged	73,400	60,800
Collateral pledged, fair value	119,600	108,800
Resale and securities borrowing agreements
Gross amounts recognized	146,096	112,662
Gross amounts offset in consolidated balance sheet	(15,248)	(15,258)
Net amounts in consolidated balance sheet	130,848	97,404
Collateral not recognized in consolidated balance sheet	(130,082)	(96,734)
Net amount	766	670
Repurchase and securities lending agreements
Gross amounts recognized	116,900	106,248
Gross amounts offset in consolidated balance sheet	(15,248)	(15,258)
Net amounts in consolidated balance sheet	101,652	90,990
Collateral pledged but not netted in consolidated balance sheet	(101,476)	(90,798)
Net amount	176	192
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	112,100	80,100
Resale and securities borrowing agreements
Net amounts in consolidated balance sheet	112,100	80,100
Loans [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Net amounts in consolidated balance sheet	18,800	17,300
Resale and securities borrowing agreements
Net amounts in consolidated balance sheet	$ 18,800	$ 17,300