Derivatives and Hedging Activities - Gain (Loss) from Interest Rate Hedges and Related Hedged Borrowings and Deposits (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Derivative [Line Items]
Interest expense	$ 3,437	$ 4,379
Interest Rate Contract [Member] \| Fair Value Hedging [Member] \| Derivative Contracts Accounted for as Hedges [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	6,586	1,256
Gain (Loss) Recognized On Hedged Borrowings and Deposits	$ (6,679)	$ (1,351)

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Amount of the cost of borrowed funds accounted for as interest expense.

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