Derivative Financial Instruments - Net Realized Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ (100)	$ 33	$ (170)	$ 84
Net Investment Income	428	397	822	779
Other net realized capital gains (losses)	(1)	(82)	(5)	(160)
Other Net Realized Capital Gains (Losses) | Fixed maturities
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	1	(2)	2	(4)
Other Net Realized Capital Gains (Losses) | Product
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(13)	12	(13)	32
Interest Credited and Other Benefits to Contract Owners | Reinsurance agreements
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(39)	20	(77)	49
Designated as Hedging Instrument | Other Net Realized Capital Gains (Losses) | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	1	1
Designated as Hedging Instrument | Cash flow hedges | Other Net Realized Capital Gains (Losses) | Interest rate contracts
Derivatives, Fair Value [Line Items]
Net realized gains (losses) on derivatives	0		0
Designated as Hedging Instrument | Cash flow hedges | Other Net Realized Capital Gains (Losses) | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Net realized gains (losses) on derivatives	0		0
Designated as Hedging Instrument | Cash flow hedges | Other Comprehensive Income (Loss) | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	1		2
Designated as Hedging Instrument | Cash flow hedges | Other Comprehensive Income (Loss) | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	16		8
Designated as Hedging Instrument | Cash flow hedges | Net Investment Income | Interest rate contracts
Derivatives, Fair Value [Line Items]
Net realized gains (losses) on derivatives			0
Designated as Hedging Instrument | Cash flow hedges | Net Investment Income | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Net realized gains (losses) on derivatives			5
Designated as Hedging Instrument | Cash flow hedges | Investment Income | Interest rate contracts
Derivatives, Fair Value [Line Items]
Net realized gains (losses) on derivatives	0		0
Designated as Hedging Instrument | Cash flow hedges | Investment Income | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Net realized gains (losses) on derivatives	3		5
Not Designated as Hedging Instrument | Other Net Realized Capital Gains (Losses) | Credit contracts
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	0	0	1	0
Not Designated as Hedging Instrument | Other Net Realized Capital Gains (Losses) | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(50)	2	(86)	7
Not Designated as Hedging Instrument | Other Net Realized Capital Gains (Losses) | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net			2	0
Not Designated as Hedging Instrument | Other Net Realized Capital Gains (Losses) | Equity contract
Derivatives, Fair Value [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 0	$ 0	$ 1	$ 0