Financial Instruments - Gain (Loss) Recognized on Derivatives Not Designated as Hedging Table (Details) - Not designated as hedging instrument - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Investment Segment | Net gain from investment activities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives not designated as hedging instruments recognized in income	[1]	$ (536)	$ (262)	$ 625	$ (1,654)
Investment Segment | Net gain from investment activities | Equity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives not designated as hedging instruments recognized in income	[1]	(657)	(213)	(886)	(1,464)
Investment Segment | Net gain from investment activities | Credit contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives not designated as hedging instruments recognized in income	[1]	121	(52)	1,511	(184)
Investment Segment | Net gain from investment activities | Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives not designated as hedging instruments recognized in income	[1]		3		(6)
Energy Segment | Cost of goods sold
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivatives not designated as hedging instruments recognized in income		$ 5	$ 18	$ 70	$ 38	[1]

[1] Gains (losses) recognized on derivatives are classified in net gain (loss) from investment activities in our condensed consolidated statements of operations for our Investment segment.