Fair Value Measurements - Assets and liabilities measured and carried at fair value in the financial statements (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Assets:
Available for sale (AFS) fixed maturities		$ 39,125	$ 38,379
Trading fixed maturities		160	348
Equity index call options		591	701
Assets of managed investment entities (“MIE”)		5,090	4,902
Variable annuity assets (separate accounts)	[1]	632	644
Total assets accounted for at fair value		47,384	46,636
Liabilities:
Liabilities of managed investment entities		4,869	4,687
Total liabilities accounted for at fair value		7,482	7,264
Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		2,549	2,542
Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		64	35
Fixed maturities
Assets:
Available for sale (AFS) fixed maturities		39,125	38,379
Trading fixed maturities		160	348
U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		250	242
States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		7,003	7,123
Foreign government
Assets:
Available for sale (AFS) fixed maturities		132	127
Residential MBS
Assets:
Available for sale (AFS) fixed maturities		3,063	3,227
Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		940	962
Asset-backed securities
Assets:
Available for sale (AFS) fixed maturities		8,663	7,962
Corporate and other
Assets:
Available for sale (AFS) fixed maturities		19,074	18,736
Equity securities
Assets:
Equity securities		1,786	1,662
Level 1
Assets:
Assets of managed investment entities (“MIE”)		301	307
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		2,026	1,914
Liabilities:
Liabilities of managed investment entities		287	293
Total liabilities accounted for at fair value		287	293
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		177	152
Trading fixed maturities		48	44
Level 1 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		147	122
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 | Asset-backed securities
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 1 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		30	30
Level 1 | Equity securities
Assets:
Equity securities		1,500	1,411
Level 2
Assets:
Assets of managed investment entities (“MIE”)		4,765	4,572
Variable annuity assets (separate accounts)	[1]	632	644
Total assets accounted for at fair value		42,758	42,432
Liabilities:
Liabilities of managed investment entities		4,559	4,372
Total liabilities accounted for at fair value		4,623	4,407
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		64	35
Level 2 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities		36,566	36,125
Trading fixed maturities		112	304
Level 2 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		95	112
Level 2 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		6,941	6,975
Level 2 | Foreign government
Assets:
Available for sale (AFS) fixed maturities		132	127
Level 2 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities		2,948	3,105
Level 2 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		893	926
Level 2 | Asset-backed securities
Assets:
Available for sale (AFS) fixed maturities		7,751	7,218
Level 2 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		17,806	17,662
Level 2 | Equity securities
Assets:
Equity securities		92	86
Level 3
Assets:
Assets of managed investment entities (“MIE”)		24	23
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		2,600	2,290
Liabilities:
Liabilities of managed investment entities		23	22
Total liabilities accounted for at fair value		2,572	2,564
Level 3 | Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		2,549	2,542
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		2,382	2,102
Trading fixed maturities		0	0
Level 3 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		8	8
Level 3 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		62	148
Level 3 | Foreign government
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 3 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities		115	122
Level 3 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		47	36
Level 3 | Asset-backed securities
Assets:
Available for sale (AFS) fixed maturities		912	744
Level 3 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		1,238	1,044
Level 3 | Equity securities
Assets:
Equity securities		194	165
Equity index call options | Equity index call options
Assets:
Equity index call options		591	701
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		591	701
Equity index call options | Level 3 | Equity index call options
Assets:
Equity index call options		$ 0	$ 0

[1] Variable annuity liabilities equal the fair value of variable annuity assets.