Derivatives and Hedging Activities - Fair Value of Derivative Assets by Type (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 1,990	$ 987
Less: Related collateral	44	207
Total derivative assets	1,946	780
Interest rate
Credit Derivatives [Line Items]
Derivative assets before collateral	1,680	848
Foreign exchange
Credit Derivatives [Line Items]
Derivative assets before collateral	28	30
Commodity
Credit Derivatives [Line Items]
Derivative assets before collateral	212	95
Credit
Credit Derivatives [Line Items]
Derivative assets before collateral	0	0
Other
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 70	$ 14