Offsetting Assets and Liabilities (Assets) (Details) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Derivatives:
Gross amounts of recognized assets	[1]	$ 5,690	$ 4,283
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial instruments	[2]	(2,971)	(2,912)
Cash collateral		(2,006)	(1,214)
Securities collateral		(273)	(73)
Net amount		440	84
OTC derivatives [Member]
Derivatives:
Gross amounts of recognized assets		5,130	4,181
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial instruments	[2]	(2,850)	(2,886)
Cash collateral		(2,006)	(1,214)
Securities collateral		(273)	(73)
Net amount		1	8
OTC cleared derivatives [Member]
Derivatives:
Gross amounts of recognized assets		96	21
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial instruments	[2]	(96)	(21)
Net amount		0	0
Exchange-traded derivatives [Member]
Derivatives:
Gross amounts of recognized assets		464	81
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial instruments	[2]	(25)	(5)
Net amount		$ 439	$ 76

[1] The fair value of freestanding derivative assets is included in Other assets on the Consolidated Balance Sheets.

[2] Represents the amount of assets that could be offset by liabilities with the same counterparty under master netting or similar arrangements that management elects not to offset on the Consolidated Balance Sheets.