Fair Value Measurements - Assets and liabilities measured and carried at fair value in the financial statements (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Assets:
Available for sale (AFS) fixed maturities		$ 34,544	$ 32,284
Trading fixed maturities		359	254
Assets of managed investment entities (MIE)		4,765	4,047
Variable annuity assets (separate accounts)	[1]	600	608
Derivatives including equity index call options and other assets		492	241
Total assets accounted for at fair value		42,319	39,155
Liabilities:
Liabilities of managed investment entities		4,549	3,781
Total liabilities accounted for at fair value		6,337	5,156
Derivatives in annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		1,759	1,369
Derivatives in long-term debt
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		(1)	(2)
Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		30	8
Fixed maturities
Assets:
Available for sale (AFS) fixed maturities		34,544	32,284
Trading fixed maturities		359	254
U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		315	307
States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		6,781	6,856
Foreign government
Assets:
Available for sale (AFS) fixed maturities		136	154
Residential MBS
Assets:
Available for sale (AFS) fixed maturities		3,635	3,529
Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		1,493	2,187
Asset-backed securities (“ABS”)
Assets:
Available for sale (AFS) fixed maturities		5,959	4,934
Corporate and other
Assets:
Available for sale (AFS) fixed maturities		16,225	14,317
Equity securities
Assets:
Equity securities — AFS and trading		1,558	1,719
Other assets — derivatives
Assets:
Derivatives including equity index call options and other assets		1	2
Level 1
Assets:
Assets of managed investment entities (MIE)		380	309
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		1,877	1,834
Liabilities:
Liabilities of managed investment entities		363	289
Total liabilities accounted for at fair value		363	289
Level 1 | Derivatives in 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		162	150
Trading fixed maturities		30	13
Level 1 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		133	100
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		29	50
Level 1 | Equity securities
Assets:
Equity securities — AFS and trading		1,305	1,362
Level 1 | Other assets — derivatives
Assets:
Derivatives including equity index call options and other assets		0	0
Level 2
Assets:
Assets of managed investment entities (MIE)		4,356	3,712
Variable annuity assets (separate accounts)	[1]	600	608
Total assets accounted for at fair value		38,680	35,685
Liabilities:
Liabilities of managed investment entities		4,158	3,468
Total liabilities accounted for at fair value		4,187	3,474
Level 2 | Derivatives in 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		(1)	(2)
Level 2 | Other liabilities — derivatives
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		30	8
Level 2 | Fixed maturities
Assets:
Available for sale (AFS) fixed maturities		32,823	30,664
Trading fixed maturities		329	241
Level 2 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		174	192
Level 2 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		6,641	6,767
Level 2 | Foreign government
Assets:
Available for sale (AFS) fixed maturities		136	154
Level 2 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities		3,445	3,305
Level 2 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		1,468	2,148
Level 2 | Asset-backed securities (“ABS”)
Assets:
Available for sale (AFS) fixed maturities		5,475	4,464
Level 2 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		15,484	13,634
Level 2 | Equity securities
Assets:
Equity securities — AFS and trading		79	217
Level 2 | Other assets — derivatives
Assets:
Derivatives including equity index call options and other assets		1	2
Level 3
Assets:
Assets of managed investment entities (MIE)		29	26
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		1,762	1,636
Liabilities:
Liabilities of managed investment entities		28	24
Total liabilities accounted for at fair value		1,787	1,393
Level 3 | Derivatives in annuity benefits accumulated
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		1,759	1,369
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		1,559	1,470
Trading fixed maturities		0	0
Level 3 | U.S. Government and government agencies
Assets:
Available for sale (AFS) fixed maturities		8	15
Level 3 | States, municipalities and political subdivisions
Assets:
Available for sale (AFS) fixed maturities		140	89
Level 3 | Foreign government
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 3 | Residential MBS
Assets:
Available for sale (AFS) fixed maturities		190	224
Level 3 | Commercial MBS
Assets:
Available for sale (AFS) fixed maturities		25	39
Level 3 | Asset-backed securities (“ABS”)
Assets:
Available for sale (AFS) fixed maturities		484	470
Level 3 | Corporate and other
Assets:
Available for sale (AFS) fixed maturities		712	633
Level 3 | Equity securities
Assets:
Equity securities — AFS and trading		174	140
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		492	241
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		492	241
Equity index call options | Level 3 | Equity index call options
Assets:
Derivatives including equity index call options and other assets		$ 0	$ 0

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