Fair Value Measurements (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Assets:
Available for sale (AFS) fixed maturities		$ 32,284	$ 30,734
Trading fixed maturities		254	266
Assets of managed investment entities (MIE)		4,047	3,108
Variable annuity assets (separate accounts)	[1]	608	662
Total assets accounted for at fair value		39,155	36,788
Liabilities:
Liabilities of managed investment entities		3,781	2,819
Total liabilities accounted for at fair value		5,156	3,992
Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		1,369	1,160
Derivatives in long-term debt [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		(2)
Other liabilities — derivatives [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		8	13
U.S. Government and government agencies [Member]
Assets:
Available for sale (AFS) fixed maturities		307	353
States, municipalities and political subdivisions [Member]
Assets:
Available for sale (AFS) fixed maturities		6,856	6,747
Foreign government [Member]
Assets:
Available for sale (AFS) fixed maturities		154	194
Residential Mortgage Backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		3,529	4,442
Commercial Mortgage Backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		2,187	2,451
Asset-backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		4,934	3,887
All other corporate [Member]
Assets:
Available for sale (AFS) fixed maturities		14,317	12,660
Fixed maturities [Member]
Assets:
Available for sale (AFS) fixed maturities		32,284	30,734
Trading fixed maturities		254	266
Equity securities [Member]
Assets:
Equity securities		1,719	1,696
Other investments — derivatives [Member]
Assets:
Derivatives included in other investments and other assets		241	322
Other assets — derivatives [Member]
Assets:
Derivatives included in other investments and other assets		2
Level 1 [Member]
Assets:
Assets of managed investment entities (MIE)		309	174
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		1,834	1,692
Liabilities:
Liabilities of managed investment entities		289	118
Total liabilities accounted for at fair value		289	118
Level 1 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0	0
Level 1 [Member] | Derivatives in long-term debt [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0
Level 1 [Member] | Other liabilities — derivatives [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0	0
Level 1 [Member] | U.S. Government and government agencies [Member]
Assets:
Available for sale (AFS) fixed maturities		100	164
Level 1 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 1 [Member] | Foreign government [Member]
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 1 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 1 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 1 [Member] | Asset-backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 1 [Member] | All other corporate [Member]
Assets:
Available for sale (AFS) fixed maturities		50	36
Level 1 [Member] | Fixed maturities [Member]
Assets:
Available for sale (AFS) fixed maturities		150	200
Trading fixed maturities		13	12
Level 1 [Member] | Equity securities [Member]
Assets:
Equity securities		1,362	1,306
Level 1 [Member] | Other investments — derivatives [Member]
Assets:
Derivatives included in other investments and other assets		0	0
Level 1 [Member] | Other assets — derivatives [Member]
Assets:
Derivatives included in other investments and other assets		0
Level 2 [Member]
Assets:
Assets of managed investment entities (MIE)		3,712	2,903
Variable annuity assets (separate accounts)	[1]	608	662
Total assets accounted for at fair value		35,685	33,741
Liabilities:
Liabilities of managed investment entities		3,468	0
Total liabilities accounted for at fair value		3,474	13
Level 2 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0	0
Level 2 [Member] | Derivatives in long-term debt [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		(2)
Level 2 [Member] | Other liabilities — derivatives [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		8	13
Level 2 [Member] | U.S. Government and government agencies [Member]
Assets:
Available for sale (AFS) fixed maturities		192	174
Level 2 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Available for sale (AFS) fixed maturities		6,767	6,647
Level 2 [Member] | Foreign government [Member]
Assets:
Available for sale (AFS) fixed maturities		154	194
Level 2 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		3,305	4,142
Level 2 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		2,148	2,407
Level 2 [Member] | Asset-backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		4,464	3,661
Level 2 [Member] | All other corporate [Member]
Assets:
Available for sale (AFS) fixed maturities		13,634	12,078
Level 2 [Member] | Fixed maturities [Member]
Assets:
Available for sale (AFS) fixed maturities		30,664	29,303
Trading fixed maturities		241	254
Level 2 [Member] | Equity securities [Member]
Assets:
Equity securities		217	297
Level 2 [Member] | Other investments — derivatives [Member]
Assets:
Derivatives included in other investments and other assets		241	322
Level 2 [Member] | Other assets — derivatives [Member]
Assets:
Derivatives included in other investments and other assets		2
Level 3 [Member]
Assets:
Assets of managed investment entities (MIE)		26	31
Variable annuity assets (separate accounts)	[1]	0	0
Total assets accounted for at fair value		1,636	1,355
Liabilities:
Liabilities of managed investment entities		24	2,701
Total liabilities accounted for at fair value		1,393	3,861
Level 3 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		1,369	1,160
Level 3 [Member] | Derivatives in long-term debt [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0
Level 3 [Member] | Other liabilities — derivatives [Member]
Liabilities:
Derivatives included in annuity benefits accumulated, long-term debt, and other liabilities		0	0
Level 3 [Member] | U.S. Government and government agencies [Member]
Assets:
Available for sale (AFS) fixed maturities		15	15
Level 3 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Available for sale (AFS) fixed maturities		89	100
Level 3 [Member] | Foreign government [Member]
Assets:
Available for sale (AFS) fixed maturities		0	0
Level 3 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		224	300
Level 3 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		39	44
Level 3 [Member] | Asset-backed Securities [Member]
Assets:
Available for sale (AFS) fixed maturities		470	226
Level 3 [Member] | All other corporate [Member]
Assets:
Available for sale (AFS) fixed maturities		633	546
Level 3 [Member] | Fixed maturities [Member]
Assets:
Available for sale (AFS) fixed maturities		1,470	1,231
Trading fixed maturities		0	0
Level 3 [Member] | Equity securities [Member]
Assets:
Equity securities		140	93
Level 3 [Member] | Other investments — derivatives [Member]
Assets:
Derivatives included in other investments and other assets		0	$ 0
Level 3 [Member] | Other assets — derivatives [Member]
Assets:
Derivatives included in other investments and other assets		$ 0

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