Fair Value Measurements - Assets and liabilities measured and carried at fair value in the financial statements (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets:
Available for sale (AFS) fixed maturities	$ 48,193	$ 46,505
Trading fixed maturities	92	113
Equity securities	1,606	1,937
Equity index call options	697	924
Assets of managed investment entities	73,110	70,130
Variable annuity assets (separate accounts)	603	628
Total assets accounted for at fair value	56,022	54,893
Liabilities:
Liabilities of managed investment entities	66,770	63,861
Total liabilities accounted for at fair value	8,207	8,311
Variable interest entity, primary beneficiary
Assets:
Assets of managed investment entities	4,717	4,736
Liabilities:
Liabilities of managed investment entities	4,541	4,571
Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	3,657	3,730
Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	9	10
Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	48,193	46,505
Trading fixed maturities	92	113
U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	224	209
States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	6,722	6,963
Foreign government
Assets:
Available for sale (AFS) fixed maturities	195	172
Residential MBS
Assets:
Available for sale (AFS) fixed maturities	3,137	3,160
Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	856	927
Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	4,607	4,280
Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	7,419	7,128
Corporate and other
Assets:
Available for sale (AFS) fixed maturities	25,033	23,666
Equity securities
Assets:
Equity securities	1,606	1,937
Other assets
Assets:
Equity index call options	114	50
Level 1
Assets:
Variable annuity assets (separate accounts)	0	0
Total assets accounted for at fair value	1,444	1,828
Liabilities:
Total liabilities accounted for at fair value	142	206
Level 1 | Variable interest entity, primary beneficiary
Assets:
Assets of managed investment entities	148	213
Liabilities:
Liabilities of managed investment entities	142	206
Level 1 | Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	0	0
Level 1 | Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	0	0
Level 1 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	206	180
Trading fixed maturities	0	2
Level 1 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	182	151
Level 1 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Foreign government
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 1 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities	24	29
Level 1 | Equity securities
Assets:
Equity securities	1,090	1,433
Level 1 | Other assets
Assets:
Equity index call options	0	0
Level 2
Assets:
Variable annuity assets (separate accounts)	603	628
Total assets accounted for at fair value	50,773	49,224
Liabilities:
Total liabilities accounted for at fair value	4,393	4,359
Level 2 | Variable interest entity, primary beneficiary
Assets:
Assets of managed investment entities	4,554	4,506
Liabilities:
Liabilities of managed investment entities	4,384	4,349
Level 2 | Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	0	0
Level 2 | Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	9	10
Level 2 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	44,641	42,938
Trading fixed maturities	92	111
Level 2 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	27	43
Level 2 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	6,616	6,858
Level 2 | Foreign government
Assets:
Available for sale (AFS) fixed maturities	195	172
Level 2 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities	2,959	2,987
Level 2 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	846	892
Level 2 | Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	4,395	4,265
Level 2 | Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	6,075	5,842
Level 2 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities	23,528	21,879
Level 2 | Equity securities
Assets:
Equity securities	72	67
Level 2 | Other assets
Assets:
Equity index call options	114	50
Level 3
Assets:
Variable annuity assets (separate accounts)	0	0
Total assets accounted for at fair value	3,805	3,841
Liabilities:
Total liabilities accounted for at fair value	3,672	3,746
Level 3 | Variable interest entity, primary beneficiary
Assets:
Assets of managed investment entities	15	17
Liabilities:
Liabilities of managed investment entities	15	16
Level 3 | Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	3,657	3,730
Level 3 | Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	0	0
Level 3 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	3,346	3,387
Trading fixed maturities	0	0
Level 3 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	15	15
Level 3 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	106	105
Level 3 | Foreign government
Assets:
Available for sale (AFS) fixed maturities	0	0
Level 3 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities	178	173
Level 3 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	10	35
Level 3 | Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	212	15
Level 3 | Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	1,344	1,286
Level 3 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities	1,481	1,758
Level 3 | Equity securities
Assets:
Equity securities	444	437
Level 3 | Other assets
Assets:
Equity index call options	0	0
Equity index call options | Equity index call options
Assets:
Equity index call options	697	924
Equity index call options | Level 1 | Equity index call options
Assets:
Equity index call options	0	0
Equity index call options | Level 2 | Equity index call options
Assets:
Equity index call options	697	924
Equity index call options | Level 3 | Equity index call options
Assets:
Equity index call options	$ 0	$ 0