Fair Value Measurements - Fair Vaue Measurement (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets:
Derivatives	$ 224	$ 128
Assets held in separate accounts	78,713	67,323
Liabilities:
Derivatives	285	99
Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	27,460	25,034
Cash, Cash Equivalents, and Short-term Investments	1,429	1,207
Assets held in separate accounts	78,713	67,323
Total assets, fair value	$ 107,906	$ 93,749
Percentage of Level to total	100.00%	100.00%
Liabilities:
Total liabilities, fair value	$ 341	$ 34
Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	536	679
Cash, Cash Equivalents, and Short-term Investments	1,429	1,207
Assets held in separate accounts	72,448	61,457
Total assets, fair value	$ 74,431	$ 63,350
Percentage of Level to total	69.00%	68.00%
Liabilities:
Total liabilities, fair value	$ 0	$ 0
Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	25,621	23,316
Cash, Cash Equivalents, and Short-term Investments	0	0
Assets held in separate accounts	6,150	5,805
Total assets, fair value	$ 31,994	$ 29,249
Percentage of Level to total	30.00%	31.00%
Liabilities:
Total liabilities, fair value	$ 308	$ 19
Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	1,303	1,039
Cash, Cash Equivalents, and Short-term Investments	0	0
Assets held in separate accounts	115	61
Total assets, fair value	$ 1,481	$ 1,150
Percentage of Level to total	1.00%	1.00%
Liabilities:
Total liabilities, fair value	$ 33	$ 15
Fixed maturities
Assets:
Fixed maturities including securities pledged, Fair Value	27,460	25,034
U.S. Treasuries
Assets:
Fixed maturities including securities pledged, Fair Value	691	738
U.S. Treasuries | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	691	738
U.S. Treasuries | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	536	679
U.S. Treasuries | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	155	59
U.S. Treasuries | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
U.S. Government agencies and authorities
Assets:
Fixed maturities including securities pledged, Fair Value	19	0
U.S. Government agencies and authorities | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	19	0
U.S. Government agencies and authorities | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
U.S. Government agencies and authorities | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	19	0
U.S. Government agencies and authorities | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
State, municipalities and political subdivisions
Assets:
Fixed maturities including securities pledged, Fair Value	815	764
State, municipalities and political subdivisions | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	815	764
State, municipalities and political subdivisions | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
State, municipalities and political subdivisions | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	815	764
State, municipalities and political subdivisions | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
U.S. corporate public securities
Assets:
Fixed maturities including securities pledged, Fair Value	8,031	8,015
U.S. corporate public securities | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	8,031	8,015
U.S. corporate public securities | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
U.S. corporate public securities | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	7,984	7,987
U.S. corporate public securities | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	47	28
U.S. corporate private securities
Assets:
Fixed maturities including securities pledged, Fair Value	4,066	3,653
U.S. corporate private securities | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	4,066	3,653
U.S. corporate private securities | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
U.S. corporate private securities | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	3,064	2,882
U.S. corporate private securities | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	1,002	771
Foreign corporate public securities and foreign governments
Assets:
Fixed maturities including securities pledged, Fair Value	2,679	2,540
Foreign corporate public securities and foreign governments | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	2,679	2,540
Foreign corporate public securities and foreign governments | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
Foreign corporate public securities and foreign governments | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	2,679	2,540
Foreign corporate public securities and foreign governments | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
Foreign corporate private securities
Assets:
Fixed maturities including securities pledged, Fair Value	3,375	3,175
Foreign corporate private securities | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	3,375	3,175
Foreign corporate private securities | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
Foreign corporate private securities | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	3,185	3,051
Foreign corporate private securities | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	190	124
Residential mortgage-backed securities
Assets:
Fixed maturities including securities pledged, Fair Value	3,810	3,036
Residential mortgage-backed securities | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	3,810	3,036
Residential mortgage-backed securities | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
Residential mortgage-backed securities | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	3,794	3,026
Residential mortgage-backed securities | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	16	10
Commercial mortgage-backed securities
Assets:
Fixed maturities including securities pledged, Fair Value	2,500	1,905
Commercial mortgage-backed securities | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	2,500	1,905
Commercial mortgage-backed securities | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
Commercial mortgage-backed securities | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	2,500	1,893
Commercial mortgage-backed securities | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	0	12
Other asset-backed securities
Assets:
Fixed maturities including securities pledged, Fair Value	1,474	1,208
Other asset-backed securities | Assets measured on recurring basis
Assets:
Fixed maturities including securities pledged, Fair Value	1,474	1,208
Other asset-backed securities | Assets measured on recurring basis | Level 1
Assets:
Fixed maturities including securities pledged, Fair Value	0	0
Other asset-backed securities | Assets measured on recurring basis | Level 2
Assets:
Fixed maturities including securities pledged, Fair Value	1,426	1,114
Other asset-backed securities | Assets measured on recurring basis | Level 3
Assets:
Fixed maturities including securities pledged, Fair Value	48	94
Equity securities | Assets measured on recurring basis
Assets:
Equity securities, available-for-sale	80	57
Equity securities | Assets measured on recurring basis | Level 1
Assets:
Equity securities, available-for-sale	17	7
Equity securities | Assets measured on recurring basis | Level 2
Assets:
Equity securities, available-for-sale	0	0
Equity securities | Assets measured on recurring basis | Level 3
Assets:
Equity securities, available-for-sale	63	50
FIA | Assets measured on recurring basis
Liabilities:
Guaranteed benefit derivatives	11	11
FIA | Assets measured on recurring basis | Level 1
Liabilities:
Guaranteed benefit derivatives	0	0
FIA | Assets measured on recurring basis | Level 2
Liabilities:
Guaranteed benefit derivatives	0	0
FIA | Assets measured on recurring basis | Level 3
Liabilities:
Guaranteed benefit derivatives	11	11
Stabilizer and MCGs | Assets measured on recurring basis
Liabilities:
Guaranteed benefit derivatives	22	4
Stabilizer and MCGs | Assets measured on recurring basis | Level 1
Liabilities:
Guaranteed benefit derivatives	0	0
Stabilizer and MCGs | Assets measured on recurring basis | Level 2
Liabilities:
Guaranteed benefit derivatives	0	0
Stabilizer and MCGs | Assets measured on recurring basis | Level 3
Liabilities:
Guaranteed benefit derivatives	22	4
Interest rate contracts | Assets measured on recurring basis
Assets:
Derivatives	210	117
Liabilities:
Derivatives	261	76
Interest rate contracts | Assets measured on recurring basis | Level 1
Assets:
Derivatives	1	0
Liabilities:
Derivatives	0	0
Interest rate contracts | Assets measured on recurring basis | Level 2
Assets:
Derivatives	209	117
Liabilities:
Derivatives	261	76
Interest rate contracts | Assets measured on recurring basis | Level 3
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Foreign exchange contracts | Assets measured on recurring basis
Assets:
Derivatives	10	10
Liabilities:
Derivatives	19	20
Foreign exchange contracts | Assets measured on recurring basis | Level 1
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Foreign exchange contracts | Assets measured on recurring basis | Level 2
Assets:
Derivatives	10	10
Liabilities:
Derivatives	19	20
Foreign exchange contracts | Assets measured on recurring basis | Level 3
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Equity contracts | Assets measured on recurring basis
Assets:
Derivatives	4	1
Liabilities:
Derivatives	3	1
Equity contracts | Assets measured on recurring basis | Level 1
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Equity contracts | Assets measured on recurring basis | Level 2
Assets:
Derivatives	4	1
Liabilities:
Derivatives	3	1
Equity contracts | Assets measured on recurring basis | Level 3
Assets:
Derivatives	0	0
Liabilities:
Derivatives	0	0
Embedded derivative on reinsurance | Assets measured on recurring basis
Liabilities:
Embedded derivative on reinsurance	23	(80)
Embedded derivative on reinsurance | Assets measured on recurring basis | Level 1
Liabilities:
Embedded derivative on reinsurance	0	0
Embedded derivative on reinsurance | Assets measured on recurring basis | Level 2
Liabilities:
Embedded derivative on reinsurance	23	(80)
Embedded derivative on reinsurance | Assets measured on recurring basis | Level 3
Liabilities:
Embedded derivative on reinsurance	0	0
Credit contracts | Assets measured on recurring basis
Liabilities:
Derivatives	2	2
Credit contracts | Assets measured on recurring basis | Level 1
Liabilities:
Derivatives	0	0
Credit contracts | Assets measured on recurring basis | Level 2
Liabilities:
Derivatives	2	2
Credit contracts | Assets measured on recurring basis | Level 3
Liabilities:
Derivatives	$ 0	$ 0