Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Assets:
Fixed maturities, Available for sale, Fair Value	$ 30,734		$ 26,456
Fixed maturities, Trading, Fair Value	266		305
Assets of managed investment entities (MIE)	3,108		2,888
Variable annuity assets (separate accounts)	662	[1]	665	[1]
Other investments — derivatives	322		274
Total assets accounted for at fair value	36,788		31,767
Liabilities:
Liabilities of managed investment entities	2,819		2,567
Total liabilities accounted for at fair value	3,992		3,381
Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	1,160		804
Other liabilities [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	13		10
U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	353		314
States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	6,747		5,372
Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	194		208
Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,442		4,310
Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	2,451		2,724
Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	3,887		2,493
All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	12,660		11,035
Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	30,734		26,456
Fixed maturities, Trading, Fair Value	266		305
Equity securities [Member]
Assets:
Equity securities, Fair Value	1,696		1,179
Level 1 [Member]
Assets:
Assets of managed investment entities (MIE)	174		266
Variable annuity assets (separate accounts)	0	[1]	0	[1]
Other investments — derivatives	0		0
Total assets accounted for at fair value	1,692		1,464
Liabilities:
Liabilities of managed investment entities	118		156
Total liabilities accounted for at fair value	118		156
Level 1 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	0		0
Level 1 [Member] | Other liabilities [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	0		0
Level 1 [Member] | U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	164		147
Level 1 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	36		28
Level 1 [Member] | Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	200		175
Fixed maturities, Trading, Fair Value	12		0
Level 1 [Member] | Equity securities [Member]
Assets:
Equity securities, Fair Value	1,306		1,023
Level 2 [Member]
Assets:
Assets of managed investment entities (MIE)	2,903		2,592
Variable annuity assets (separate accounts)	662	[1]	665	[1]
Other investments — derivatives	322		274
Total assets accounted for at fair value	33,741		29,412
Liabilities:
Liabilities of managed investment entities	0		0
Total liabilities accounted for at fair value	13		10
Level 2 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	0		0
Level 2 [Member] | Other liabilities [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	13		10
Level 2 [Member] | U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	174		152
Level 2 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	6,647		5,311
Level 2 [Member] | Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	194		208
Level 2 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,142		3,994
Level 2 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	2,407		2,696
Level 2 [Member] | Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	3,661		2,418
Level 2 [Member] | All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	12,078		10,672
Level 2 [Member] | Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	29,303		25,451
Fixed maturities, Trading, Fair Value	254		305
Level 2 [Member] | Equity securities [Member]
Assets:
Equity securities, Fair Value	297		125
Level 3 [Member]
Assets:
Assets of managed investment entities (MIE)	31		30
Variable annuity assets (separate accounts)	0	[1]	0	[1]
Other investments — derivatives	0		0
Total assets accounted for at fair value	1,355		891
Liabilities:
Liabilities of managed investment entities	2,701		2,411
Total liabilities accounted for at fair value	3,861		3,215
Level 3 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	1,160		804
Level 3 [Member] | Other liabilities [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	0		0
Level 3 [Member] | U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	15		15
Level 3 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	100		61
Level 3 [Member] | Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 3 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	300		316
Level 3 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	44		28
Level 3 [Member] | Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	226		75
Level 3 [Member] | All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	546		335
Level 3 [Member] | Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	1,231		830
Fixed maturities, Trading, Fair Value	0		0
Level 3 [Member] | Equity securities [Member]
Assets:
Equity securities, Fair Value	$ 93		$ 31

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