Fair Value Measurements - Assets and liabilities measured and carried at fair value in the financial statements (Details) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Assets:
Available for sale (AFS) fixed maturities		$ 39,648	$ 38,379
Trading fixed maturities		137	348
Equity index call options		615	701
Assets of managed investment entities (“MIE”)		5,032	4,902
Variable annuity assets (separate accounts)	[1]	636	644
Total assets accounted for at fair value		47,845	46,636
Liabilities:
Liabilities of managed investment entities		4,840	4,687
Total liabilities accounted for at fair value		7,688	7,264
Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		2,776	2,542
Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		72	35
Fixed maturities
Assets:
Available for sale (AFS) fixed maturities		39,648	38,379
Trading fixed maturities		137	348
U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		240	242
States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		6,913	7,123
Foreign government
Assets:
Available for sale (AFS) fixed maturities		129	127
Residential MBS
Assets:
Available for sale (AFS) fixed maturities		2,886	3,227
Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		934	962
Asset-backed securities
Assets:
Available for sale (AFS) fixed maturities		8,935	7,962
Corporate and other
Assets:
Available for sale (AFS) fixed maturities		19,611	18,736
Equity securities
Assets:
Equity securities		1,777	1,662
Level 1
Assets:
Assets of managed investment entities (“MIE”)		229	307
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		1,907	1,914
Liabilities:
Liabilities of managed investment entities		220	293
Total liabilities accounted for at fair value		220	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		169	152
Trading fixed maturities		38	44
Level 1 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		140	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		29	30
Level 1 | Equity securities
Assets:
Equity securities		1,471	1,411
Level 2
Assets:
Assets of managed investment entities (“MIE”)		4,780	4,572
Variable annuity assets (separate accounts)	[1]	636	644
Total assets accounted for at fair value		43,001	42,432
Liabilities:
Liabilities of managed investment entities		4,598	4,372
Total liabilities accounted for at fair value		4,670	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		72	35
Level 2 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities		36,795	36,125
Trading fixed maturities		99	304
Level 2 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		92	112
Level 2 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		6,852	6,975
Level 2 | Foreign government
Assets:
Available for sale (AFS) fixed maturities		129	127
Level 2 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities		2,739	3,105
Level 2 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		878	926
Level 2 | Asset-backed securities
Assets:
Available for sale (AFS) fixed maturities		7,931	7,218
Level 2 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		18,174	17,662
Level 2 | Equity securities
Assets:
Equity securities		76	86
Level 3
Assets:
Assets of managed investment entities (“MIE”)		23	23
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		2,937	2,290
Liabilities:
Liabilities of managed investment entities		22	22
Total liabilities accounted for at fair value		2,798	2,564
Level 3 | Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		2,776	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		2,684	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		61	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		147	122
Level 3 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		56	36
Level 3 | Asset-backed securities
Assets:
Available for sale (AFS) fixed maturities		1,004	744
Level 3 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		1,408	1,044
Level 3 | Equity securities
Assets:
Equity securities		230	165
Equity index call options | Equity index call options
Assets:
Equity index call options		615	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		615	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.