Fair Value of Financial Instruments - Carrying Amounts of Assets and Liabilities at Estimated Fair Value Measured on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets
Fixed maturity securities, available for sale	$ 26,410	$ 2,090
Derivative investments	381	0
Total financial assets at fair value	2,850
Level 1
Assets
Cash and cash equivalents	2,871	1,376
Equity securities		810
Derivative investments	0
Short term investments	119	876
Total financial assets at fair value	4,813	3,127
Liabilities
Fair value of future policy benefits	0
Derivatives:
Total financial liabilities at fair value	0
Level 2
Assets
Cash and cash equivalents	0	0
Equity securities		0
Derivative investments	381
Short term investments	0	0
Total financial assets at fair value	24,129	2,331
Liabilities
Fair value of future policy benefits	0
Derivatives:
Total financial liabilities at fair value	49
Level 3
Assets
Cash and cash equivalents	0	0
Equity securities		1
Derivative investments	0
Short term investments	0	0
Total financial assets at fair value	2,850	138
Liabilities
Fair value of future policy benefits	5
Derivatives:
Total financial liabilities at fair value	3,166
Fair Value
Assets
Cash and cash equivalents	2,871	1,376
Equity securities		811
Derivative investments	381
Short term investments	119	876
Total financial assets at fair value	31,792	5,596
Liabilities
Fair value of future policy benefits	5
Derivatives:
Total financial liabilities at fair value	3,215
Carrying Value
Assets
Cash and cash equivalents	2,871	1,376
Equity securities		811
Derivative investments	381
Short term investments	119	876
Total financial assets at fair value	31,792	5,596
Liabilities
Fair value of future policy benefits	5
Derivatives:
Total financial liabilities at fair value	3,215
FIA embedded derivatives, included in contractholder funds \| Level 1
Derivatives:
Derivative liability	0
FIA embedded derivatives, included in contractholder funds \| Level 2
Derivatives:
Derivative liability	0
FIA embedded derivatives, included in contractholder funds \| Level 3
Derivatives:
Derivative liability	3,161
FIA embedded derivatives, included in contractholder funds \| Fair Value
Derivatives:
Derivative liability	3,161
FIA embedded derivatives, included in contractholder funds \| Carrying Value
Derivatives:
Derivative liability	3,161
Reinsurance related embedded derivatives, included in accounts payable and accrued liabilities \| Level 1
Derivatives:
Derivative liability	0
Reinsurance related embedded derivatives, included in accounts payable and accrued liabilities \| Level 2
Derivatives:
Derivative liability	49
Reinsurance related embedded derivatives, included in accounts payable and accrued liabilities \| Level 3
Derivatives:
Derivative liability	0
Reinsurance related embedded derivatives, included in accounts payable and accrued liabilities \| Fair Value
Derivatives:
Derivative liability	49
Reinsurance related embedded derivatives, included in accounts payable and accrued liabilities \| Carrying Value
Derivatives:
Derivative liability	49
Asset-backed securities
Assets
Fixed maturity securities, available for sale	5,739
Asset-backed securities \| Level 1
Assets
Fixed maturity securities, available for sale	0
Asset-backed securities \| Level 2
Assets
Fixed maturity securities, available for sale	4,795
Asset-backed securities \| Level 3
Assets
Fixed maturity securities, available for sale	944
Asset-backed securities \| Fair Value
Assets
Fixed maturity securities, available for sale	5,739
Asset-backed securities \| Carrying Value
Assets
Fixed maturity securities, available for sale	5,739
Commercial mortgage-backed securities
Assets
Fixed maturity securities, available for sale	2,772	22
Commercial mortgage-backed securities \| Level 1
Assets
Fixed maturity securities, available for sale	0	0
Commercial mortgage-backed securities \| Level 2
Assets
Fixed maturity securities, available for sale	2,746	22
Commercial mortgage-backed securities \| Level 3
Assets
Fixed maturity securities, available for sale	26	0
Commercial mortgage-backed securities \| Fair Value
Assets
Fixed maturity securities, available for sale	2,772	22
Commercial mortgage-backed securities \| Carrying Value
Assets
Fixed maturity securities, available for sale	2,772	22
Corporates
Assets
Fixed maturity securities, available for sale	13,965	1,556
Corporates \| Level 1
Assets
Fixed maturity securities, available for sale	0	0
Corporates \| Level 2
Assets
Fixed maturity securities, available for sale	12,698	1,540
Corporates \| Level 3
Assets
Fixed maturity securities, available for sale	1,267	17
Corporates \| Fair Value
Assets
Fixed maturity securities, available for sale	13,965	1,557
Corporates \| Carrying Value
Assets
Fixed maturity securities, available for sale	13,965	1,557
Hybrids
Assets
Fixed maturity securities, available for sale	993	31
Hybrids \| Level 1
Assets
Fixed maturity securities, available for sale	250	0
Hybrids \| Level 2
Assets
Fixed maturity securities, available for sale	739	30
Hybrids \| Level 3
Assets
Fixed maturity securities, available for sale	4	0
Hybrids \| Fair Value
Assets
Fixed maturity securities, available for sale	993	30
Hybrids \| Carrying Value
Assets
Fixed maturity securities, available for sale	993	30
Municipals \| Level 1
Assets
Fixed maturity securities, available for sale	0	0
Municipals \| Level 2
Assets
Fixed maturity securities, available for sale	1,424	93
Municipals \| Level 3
Assets
Fixed maturity securities, available for sale	42	0
Municipals \| Fair Value
Assets
Fixed maturity securities, available for sale	1,466	93
Municipals \| Carrying Value
Assets
Fixed maturity securities, available for sale	1,466	93
Residential mortgage-backed securities
Assets
Fixed maturity securities, available for sale	882	40
Residential mortgage-backed securities \| Level 1
Assets
Fixed maturity securities, available for sale	0	0
Residential mortgage-backed securities \| Level 2
Assets
Fixed maturity securities, available for sale	381	40
Residential mortgage-backed securities \| Level 3
Assets
Fixed maturity securities, available for sale	501	0
Residential mortgage-backed securities \| Fair Value
Assets
Fixed maturity securities, available for sale	882	40
Residential mortgage-backed securities \| Carrying Value
Assets
Fixed maturity securities, available for sale	882	40
U.S. Government
Assets
Fixed maturity securities, available for sale	405	288
U.S. Government \| Level 1
Assets
Fixed maturity securities, available for sale	405	0
U.S. Government \| Level 2
Assets
Fixed maturity securities, available for sale	0	288
U.S. Government \| Level 3
Assets
Fixed maturity securities, available for sale	0	0
U.S. Government \| Fair Value
Assets
Fixed maturity securities, available for sale	405	288
U.S. Government \| Carrying Value
Assets
Fixed maturity securities, available for sale	405	288
Foreign Governments
Assets
Fixed maturity securities, available for sale	188	60
Foreign Governments \| Level 1
Assets
Fixed maturity securities, available for sale	0	0
Foreign Governments \| Level 2
Assets
Fixed maturity securities, available for sale	172	60
Foreign Governments \| Level 3
Assets
Fixed maturity securities, available for sale	16	0
Foreign Governments \| Fair Value
Assets
Fixed maturity securities, available for sale	188	60
Foreign Governments \| Carrying Value
Assets
Fixed maturity securities, available for sale	188	60
Equity securities \| Level 1
Assets
Equity securities	688
Equity securities \| Level 2
Assets
Equity securities	0
Equity securities \| Level 3
Assets
Equity securities	3
Equity securities \| Fair Value
Assets
Equity securities	691
Equity securities \| Carrying Value
Assets
Equity securities	691
Preferred securities
Assets
Equity securities	1,274	323
Preferred securities \| Level 1
Assets
Equity securities	480	65
Preferred securities \| Level 2
Assets
Equity securities	793	258
Preferred securities \| Level 3
Assets
Equity securities	1	0
Preferred securities \| Fair Value
Assets
Equity securities	1,274	323
Preferred securities \| Carrying Value
Assets
Equity securities	1,274	323
Other long-term investments \| Level 1
Assets
Other long-term investments	0	0
Other long-term investments \| Level 2
Assets
Other long-term investments	0	0
Other long-term investments \| Level 3
Assets
Other long-term investments	46	120
Other long-term investments \| Fair Value
Assets
Other long-term investments	46	120
Other long-term investments \| Carrying Value
Assets
Other long-term investments	$ 46	$ 120

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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