Trading Assets and Liabilities - Summary of Trading Assets and Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Trading Assets	$ 408,400	$ 355,332
Trading Liabilities	162,141	108,835
Trading Cash Instruments [Member]
Trading Cash Instruments	343,880	310,080
Trading Liabilities	105,443	65,033
Derivatives [Member]
Trading Assets at Fair Value	64,520	45,252
Trading Liabilities	$ 56,698	$ 43,802

The carrying amount of liabilities as of the balance sheet date that pertain to principal and customer trading transactions, or which may be incurred with the objective of generating a profit from short-term fluctuations in price as part of an entity's market-making, hedging and proprietary trading. Examples include short positions in securities, derivatives and commodities, obligations under repurchase agreements, and securities borrowed arrangements.

No definition available.

Name:	us-gaap_TradingLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant