Derivative Instruments - Summary of Notional and Fair Value of Derivative Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Funds withheld at interest	$ 48,593	$ 15,181
Funds withheld liability	440	408
Derivative assets, fair value	2,771	2,888
Derivative liabilities, fair value	147	97
Total derivative assets	4,751	4,283
Total derivative liabilities	11,938	11,070
Derivatives designated as hedges
Derivative [Line Items]
Derivative assets, fair value	258	114
Derivative liabilities, fair value	$ 47	$ 67
Derivatives designated as hedges | Foreign currency swaps
Derivative [Line Items]
Notional Amount	3,268	3,158
Derivative assets, fair value	$ 243	$ 113
Derivative liabilities, fair value	$ 45	$ 56
Derivatives designated as hedges | Foreign currency forwards
Derivative [Line Items]
Notional Amount	1,736	717
Derivative assets, fair value	$ 15	$ 1
Derivative liabilities, fair value	1	9
Derivatives not designated as hedges
Derivative [Line Items]
Total derivative assets	4,493	4,169
Total derivative liabilities	$ 11,891	$ 11,003
Derivatives not designated as hedges | Foreign currency swaps
Derivative [Line Items]
Notional Amount	1,510	35
Derivative assets, fair value	$ 25	$ 2
Derivative liabilities, fair value	$ 8	$ 1
Derivatives not designated as hedges | Interest rate swaps
Derivative [Line Items]
Notional Amount	911	776
Derivative assets, fair value	$ 11	$ 3
Derivative liabilities, fair value	$ 41	$ 4
Derivatives not designated as hedges | Equity options
Derivative [Line Items]
Notional Amount	53,997	49,549
Derivative assets, fair value	$ 2,401	$ 2,746
Derivative liabilities, fair value	$ 26	$ 5
Derivatives not designated as hedges | Futures
Derivative [Line Items]
Notional Amount	16	8
Derivative assets, fair value	$ 48	$ 10
Derivative liabilities, fair value	$ 4	$ 1
Derivatives not designated as hedges | Total return swaps
Derivative [Line Items]
Notional Amount	72	106
Derivative assets, fair value	$ 1	$ 6
Derivative liabilities, fair value	$ 0	$ 0
Derivatives not designated as hedges | Credit default swaps
Derivative [Line Items]
Notional Amount	10	10
Derivative assets, fair value	$ 0	$ 0
Derivative liabilities, fair value	$ 5	$ 3
Derivatives not designated as hedges | Foreign currency forwards
Derivative [Line Items]
Notional Amount	2,963	1,924
Derivative assets, fair value	$ 27	$ 7
Derivative liabilities, fair value	16	16
Derivatives not designated as hedges | Embedded derivatives | Funds withheld
Derivative [Line Items]
Funds withheld at interest	1,980
Funds withheld liability	50
Embedded derivative assets, fair value		1,395
Embedded derivative liabilities, fair value		31
Derivatives not designated as hedges | Embedded derivatives | Interest sensitive contract liabilities
Derivative [Line Items]
Embedded derivative assets, fair value	0	0
Embedded derivative liabilities, fair value	$ 11,741	$ 10,942
Net Investment Hedging [Member] | Derivatives designated as hedges | Foreign currency forwards
Derivative [Line Items]
Notional Amount	136	139
Derivative assets, fair value	$ 0	$ 0
Derivative liabilities, fair value	$ 1	$ 2