Financial Instruments Derivatives Not Designated as Hedging, Fair Value Table (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Derivative contracts, at fair value (Note 6)		$ 36	$ 1,275
Not designated as hedging instrument | Other assets
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Asset derivatives, Gross	[1]	659	7
Derivative, Fair Value, Amount Offset Against Collateral, Net	[1],[2]	(135)	(7)
Derivative contracts, at fair value(1)	[1],[2]	524	0
Not designated as hedging instrument | Accrued expenses and other liabilities
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Liability derivatives, Gross		171	1,282
Derivative, Fair Value, Amount Offset Against Collateral, Net	[2]	(135)	(7)
Derivative contracts, at fair value (Note 6)	[2]	36	1,275
Not designated as hedging instrument | Equity contracts | Other assets
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Asset derivatives, Gross	[1]	568	0
Not designated as hedging instrument | Equity contracts | Accrued expenses and other liabilities
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Liability derivatives, Gross		170	1,159
Not designated as hedging instrument | Credit contracts | Other assets
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Asset derivatives, Gross	[1]	76	0
Not designated as hedging instrument | Credit contracts | Accrued expenses and other liabilities
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Liability derivatives, Gross		0	17
Not designated as hedging instrument | Commodity contracts | Other assets
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Asset derivatives, Gross	[1]	15	7
Not designated as hedging instrument | Commodity contracts | Accrued expenses and other liabilities
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Liability derivatives, Gross		1	106
Investment Segment
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Collateral posted on certain derivative positions		0	542
Investment Segment | Credit Default Swap [Member]
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Derivative, Notional Amount		1,800	2,500
Investment Segment | Equity contracts
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Notional Exposure of Derivatives, Long Position		118	243
Short Notional Exposure		8,368	6,660
Investment Segment | Credit contracts
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Notional Exposure of Derivatives, Long Position	[3]	0	0
Short Notional Exposure	[3]	479	391
Investment Segment | Commodity contracts
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Notional Exposure of Derivatives, Long Position		0	0
Short Notional Exposure		114	634
Other Operating Income (Expense) [Member] | Energy Segment | Not designated as hedging instrument
Derivatives Not Designated as Hedging Instruments, Fair Value [Line Items]
Derivative gain (loss) recognized in income		$ 146	$ (70)	$ (19)

[1] Net asset derivatives are located within other assets in our consolidated balance sheets.

[2] Excludes netting of cash collateral received and posted. The total collateral posted at December 31, 2018 and 2017 was $0 million and $542 million, respectively, across all counterparties, which are included in cash held at consolidated affiliated partnerships and restricted cash in our consolidated balance sheets.

[3] The short notional amount on our credit default swap positions was approximately $1.8 billion as of December 31, 2018. However, because credit spreads cannot compress below zero, our downside short notional exposure is $479 million as of December 31, 2018. The short notional amount on our credit default swap positions was approximately $2.5 billion as of December 31, 2017. However, because credit spreads cannot compress below zero, our downside short notional exposure to loss is $391 million as of December 31, 2017.