Derivative Financial Instrument - Effect of derivative qualified as hedge accounting (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	$ (148)	$ (117)
Interest rate contracts | Other net realized capital gains/(losses) | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	(37)	(52)
Foreign exchange contracts | Other net realized capital gains/(losses) | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	7	2
Equity contracts | Other net realized capital gains/(losses) | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	0	(16)
Fixed maturities | Other net realized capital gains/(losses)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	8	1
Within products | Other net realized capital gains/(losses)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	(167)	4
Embedded derivative on reinsurance | Policyholder Benefits
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	65	(59)
Managed custody guarantees
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	(26)
Managed custody guarantees | Other net realized capital gains/(losses)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net		0
Credit contracts | Other net realized capital gains/(losses) | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	2	3
Discontinued Operations, Held-for-sale
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	(5)	2
Discontinued Operations, Held-for-sale | Foreign exchange contracts | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	1	0
Discontinued Operations, Held-for-sale | Equity contracts | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	(153)	63
Discontinued Operations, Held-for-sale | Fixed maturities
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	2	0
Discontinued Operations, Held-for-sale | Within products
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	145	(62)
Discontinued Operations, Held-for-sale | Credit contracts | Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	$ 0	$ 1