Fair Value Measurements - Assets and liabilities measured and carried at fair value in the financial statements (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Available for sale (AFS) fixed maturities	$ 43,207	$ 46,505
Trading fixed maturities	66	113
Equity securities, at fair value	1,663	1,937
Assets of managed investment entities	73,566	70,130	$ 63,456
Variable annuity assets (separate accounts)	664	628
Derivatives including equity index call options and other assets	825	924
Total assets accounted for at fair value	51,498	54,893
Liabilities:
Liabilities of managed investment entities	66,777	63,861
Total liabilities accounted for at fair value	8,714	8,311
Variable interest entity, primary beneficiary
Assets:
Assets of managed investment entities	4,971	4,736
Liabilities:
Liabilities of managed investment entities	4,771	4,571
Derivatives in annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	3,933	3,730
Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	10	10
Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	43,207	46,505
Trading fixed maturities	66	113
U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	242	209
States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	5,733	6,963
Foreign government
Assets:
Available for sale (AFS) fixed maturities	211	172
Residential MBS
Assets:
Available for sale (AFS) fixed maturities	3,055	3,160
Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	790	927
Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	4,553	4,280
Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	7,223	7,128
Corporate and other
Assets:
Available for sale (AFS) fixed maturities	21,400	23,666
Equity securities
Assets:
Equity securities, at fair value	1,663	1,937
Other assets — derivatives
Assets:
Derivatives including equity index call options and other assets	102	50
Level 1
Assets:
Variable annuity assets (separate accounts)	0	0
Total assets accounted for at fair value	1,558	1,828
Liabilities:
Total liabilities accounted for at fair value	208	206
Level 1 | Variable interest entity, primary beneficiary
Assets:
Assets of managed investment entities	217	213
Liabilities:
Liabilities of managed investment entities	208	206
Level 1 | Derivatives in 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	245	180
Trading fixed maturities	0	2
Level 1 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	201	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	44	29
Level 1 | Equity securities
Assets:
Equity securities, at fair value	1,096	1,433
Level 1 | Other assets — derivatives
Assets:
Derivatives including equity index call options and other assets	0	0
Level 2
Assets:
Variable annuity assets (separate accounts)	664	628
Total assets accounted for at fair value	46,234	49,224
Liabilities:
Total liabilities accounted for at fair value	4,553	4,359
Level 2 | Variable interest entity, primary beneficiary
Assets:
Assets of managed investment entities	4,733	4,506
Liabilities:
Liabilities of managed investment entities	4,543	4,349
Level 2 | Derivatives in 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	10	10
Level 2 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities	39,746	42,938
Trading fixed maturities	66	111
Level 2 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities	26	43
Level 2 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities	5,630	6,858
Level 2 | Foreign government
Assets:
Available for sale (AFS) fixed maturities	211	172
Level 2 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities	2,890	2,987
Level 2 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	777	892
Level 2 | Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	4,489	4,265
Level 2 | Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	5,850	5,842
Level 2 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities	19,873	21,879
Level 2 | Equity securities
Assets:
Equity securities, at fair value	98	67
Level 2 | Other assets — derivatives
Assets:
Derivatives including equity index call options and other assets	102	50
Level 3
Assets:
Variable annuity assets (separate accounts)	0	0
Total assets accounted for at fair value	3,706	3,841
Liabilities:
Total liabilities accounted for at fair value	3,953	3,746
Level 3 | Variable interest entity, primary beneficiary
Assets:
Assets of managed investment entities	21	17
Liabilities:
Liabilities of managed investment entities	20	16
Level 3 | Derivatives in annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities	3,933	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	3,216	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	103	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	165	173
Level 3 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities	13	35
Level 3 | Collateralized loan obligations
Assets:
Available for sale (AFS) fixed maturities	64	15
Level 3 | Other asset-backed securities
Assets:
Available for sale (AFS) fixed maturities	1,373	1,286
Level 3 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities	1,483	1,758
Level 3 | Equity securities
Assets:
Equity securities, at fair value	469	437
Level 3 | Other assets — derivatives
Assets:
Derivatives including equity index call options and other assets	0	0
Equity index call options | Equity index call options
Assets:
Derivatives including equity index call options and other assets	825	924
Equity index call options | Level 1 | Equity index call options
Assets:
Derivatives including equity index call options and other assets	0	0
Equity index call options | Level 2 | Equity index call options
Assets:
Derivatives including equity index call options and other assets	825	924
Equity index call options | Level 3 | Equity index call options
Assets:
Derivatives including equity index call options and other assets	$ 0	$ 0