Fair Value Measurements - Assets and liabilities measured and carried at fair value in the financial statements (Details) - USD ($) $ in Millions		Jun. 30, 2017	Dec. 31, 2016
Assets:
Available for sale (AFS) fixed maturities		$ 37,504	$ 34,544
Trading fixed maturities		339	359
Assets of managed investment entities (“MIE”)		4,873	4,765
Variable annuity assets (separate accounts)	[1]	620	600
Derivatives included in other investments and other assets		589	492
Total assets accounted for at fair value		45,566	42,319
Liabilities:
Liabilities of managed investment entities		4,685	4,549
Total liabilities accounted for at fair value		6,843	6,337
Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		2,129	1,759
Derivatives in long-term debt
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0	(1)
Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		29	30
Fixed maturities
Assets:
Available for sale (AFS) fixed maturities		37,504	34,544
Trading fixed maturities		339	359
U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		276	315
States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		7,030	6,781
Foreign government
Assets:
Available for sale (AFS) fixed maturities		140	136
Residential MBS
Assets:
Available for sale (AFS) fixed maturities		3,564	3,635
Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		1,085	1,493
Asset-backed securities (“ABS”)
Assets:
Available for sale (AFS) fixed maturities		7,190	5,959
Corporate and other
Assets:
Available for sale (AFS) fixed maturities		18,219	16,225
Equity securities
Assets:
Equity securities — AFS and trading		1,640	1,558
Other assets — derivatives
Assets:
Derivatives included in other investments and other assets		1	1
Level 1
Assets:
Assets of managed investment entities (“MIE”)		536	380
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		2,123	1,877
Liabilities:
Liabilities of managed investment entities		516	363
Total liabilities accounted for at fair value		516	363
Level 1 | Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0	0
Level 1 | Derivatives in long-term debt
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		152	162
Trading fixed maturities		35	30
Level 1 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		121	133
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 (“ABS”)
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 1 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		31	29
Level 1 | Equity securities
Assets:
Equity securities — AFS and trading		1,400	1,305
Level 1 | Other assets — derivatives
Assets:
Derivatives included in other investments and other assets		0	0
Level 2
Assets:
Assets of managed investment entities (“MIE”)		4,314	4,356
Variable annuity assets (separate accounts)	[1]	620	600
Total assets accounted for at fair value		41,452	38,680
Liabilities:
Liabilities of managed investment entities		4,147	4,158
Total liabilities accounted for at fair value		4,176	4,187
Level 2 | Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0	0
Level 2 | Derivatives in long-term debt
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0	(1)
Level 2 | Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		29	30
Level 2 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities		35,552	32,823
Trading fixed maturities		304	329
Level 2 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		147	174
Level 2 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		6,887	6,641
Level 2 | Foreign government
Assets:
Available for sale (AFS) fixed maturities		140	136
Level 2 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities		3,411	3,445
Level 2 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		1,040	1,468
Level 2 | Asset-backed securities (“ABS”)
Assets:
Available for sale (AFS) fixed maturities		6,692	5,475
Level 2 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		17,235	15,484
Level 2 | Equity securities
Assets:
Equity securities — AFS and trading		72	79
Level 2 | Other assets — derivatives
Assets:
Derivatives included in other investments and other assets		1	1
Level 3
Assets:
Assets of managed investment entities (“MIE”)		23	29
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		1,991	1,762
Liabilities:
Liabilities of managed investment entities		22	28
Total liabilities accounted for at fair value		2,151	1,787
Level 3 | Annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		2,129	1,759
Level 3 | Derivatives in long-term debt
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0	0
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		1,800	1,559
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		143	140
Level 3 | Foreign government
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 3 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities		153	190
Level 3 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		45	25
Level 3 | Asset-backed securities (“ABS”)
Assets:
Available for sale (AFS) fixed maturities		498	484
Level 3 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		953	712
Level 3 | Equity securities
Assets:
Equity securities — AFS and trading		168	174
Level 3 | Other assets — derivatives
Assets:
Derivatives included in other investments and other assets		0	0
Equity index call options | Equity index call options
Assets:
Derivatives included in other investments and other assets		589	492
Equity index call options | Level 1 | Equity index call options
Assets:
Derivatives included in other investments and other assets		0	0
Equity index call options | Level 2 | Equity index call options
Assets:
Derivatives included in other investments and other assets		589	492
Equity index call options | Level 3 | Equity index call options
Assets:
Derivatives included in other investments and other assets		$ 0	$ 0

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