Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Assets:
Fixed maturities, Available for sale, Fair Value	$ 31,968		$ 30,734
Fixed maturities, Trading, Fair Value	273		266
Assets of managed investment entities (MIE)	3,279		3,108
Variable annuity assets (separate accounts)	667	[1]	662	[1]
Other investments — derivatives	318		322
Total assets accounted for at fair value	38,215		36,788
Liabilities:
Liabilities of managed investment entities	2,952		2,819
Total liabilities accounted for at fair value	4,208		3,992
Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	1,243		1,160
Other liabilities [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	13		13
U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	330		353
States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	7,106		6,747
Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	184		194
Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,325		4,442
Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	2,403		2,451
Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,224		3,887
All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	13,396		12,660
Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	31,968		30,734
Fixed maturities, Trading, Fair Value	273		266
Equity securities [Member]
Assets:
Equity securities, Fair Value	1,710		1,696
Level 1 [Member]
Assets:
Assets of managed investment entities (MIE)	120		174
Variable annuity assets (separate accounts)	0	[1]	0	[1]
Other investments — derivatives	0		0
Total assets accounted for at fair value	1,682		1,692
Liabilities:
Liabilities of managed investment entities	108		118
Total liabilities accounted for at fair value	108		118
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	123		164
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	38		36
Level 1 [Member] | Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	161		200
Fixed maturities, Trading, Fair Value	13		12
Level 1 [Member] | Equity securities [Member]
Assets:
Equity securities, Fair Value	1,388		1,306
Level 2 [Member]
Assets:
Assets of managed investment entities (MIE)	3,130		2,903
Variable annuity assets (separate accounts)	667	[1]	662	[1]
Other investments — derivatives	318		322
Total assets accounted for at fair value	35,200		33,741
Liabilities:
Liabilities of managed investment entities	2,818		0
Total liabilities accounted for at fair value	2,831		13
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		13
Level 2 [Member] | U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	192		174
Level 2 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	7,045		6,647
Level 2 [Member] | Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	184		194
Level 2 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,019		4,142
Level 2 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	2,359		2,407
Level 2 [Member] | Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,013		3,661
Level 2 [Member] | All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	12,775		12,078
Level 2 [Member] | Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	30,587		29,303
Fixed maturities, Trading, Fair Value	260		254
Level 2 [Member] | Equity securities [Member]
Assets:
Equity securities, Fair Value	238		297
Level 3 [Member]
Assets:
Assets of managed investment entities (MIE)	29		31
Variable annuity assets (separate accounts)	0	[1]	0	[1]
Other investments — derivatives	0		0
Total assets accounted for at fair value	1,333		1,355
Liabilities:
Liabilities of managed investment entities	26		2,701
Total liabilities accounted for at fair value	1,269		3,861
Level 3 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	1,243		1,160
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	61		100
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	306		300
Level 3 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	44		44
Level 3 [Member] | Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	211		226
Level 3 [Member] | All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	583		546
Level 3 [Member] | Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	1,220		1,231
Fixed maturities, Trading, Fair Value	0		0
Level 3 [Member] | Equity securities [Member]
Assets:
Equity securities, Fair Value	$ 84		$ 93

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