Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Assets:
Trading fixed maturities	$ 307		$ 321
Assets of managed investment entities (MIE)	3,285		3,225
Total assets accounted for at fair value	30,241		29,316
Liabilities:
Liabilities of managed investment entities	2,880		2,892
Derivatives in annuity benefits accumulated	555		465
Derivative liability, at fair value	16		17
Total liabilities accounted for at fair value	3,451		3,374
Level 1 [Member]
Assets:
Trading fixed maturities
Assets of managed investment entities (MIE)	354		256
Total assets accounted for at fair value	1,410		1,269
Liabilities:
Liabilities of managed investment entities	379		147
Derivatives in annuity benefits accumulated
Derivative liability, at fair value
Total liabilities accounted for at fair value	379		147
Level 2 [Member]
Assets:
Trading fixed maturities	307		321
Assets of managed investment entities (MIE)	2,901		2,929
Total assets accounted for at fair value	27,805		27,010
Liabilities:
Liabilities of managed investment entities
Derivatives in annuity benefits accumulated
Derivative liability, at fair value	16		17
Total liabilities accounted for at fair value	16		17
Level 3 [Member]
Assets:
Trading fixed maturities
Assets of managed investment entities (MIE)	30		40
Total assets accounted for at fair value	1,026		1,037
Liabilities:
Liabilities of managed investment entities	2,501		2,745
Derivatives in annuity benefits accumulated	555		465
Derivative liability, at fair value
Total liabilities accounted for at fair value	3,056		3,210
Fixed Maturity [Member]
Assets:
Total AFS securities	24,775		24,118
Fixed Maturity [Member] | Level 1 [Member]
Assets:
Total AFS securities	175		232
Fixed Maturity [Member] | Level 2 [Member]
Assets:
Total AFS securities	23,653		22,926
Fixed Maturity [Member] | Level 3 [Member]
Assets:
Total AFS securities	947		960
U.S. Government and government agencies [Member]
Assets:
Total AFS securities	342		388
U.S. Government and government agencies [Member] | Level 1 [Member]
Assets:
Total AFS securities	170		227
U.S. Government and government agencies [Member] | Level 2 [Member]
Assets:
Total AFS securities	152		141
U.S. Government and government agencies [Member] | Level 3 [Member]
Assets:
Total AFS securities	20		20
States, municipalities and political subdivisions [Member]
Assets:
Total AFS securities	4,644		4,468
States, municipalities and political subdivisions [Member] | Level 1 [Member]
Assets:
Total AFS securities
States, municipalities and political subdivisions [Member] | Level 2 [Member]
Assets:
Total AFS securities	4,590		4,410
States, municipalities and political subdivisions [Member] | Level 3 [Member]
Assets:
Total AFS securities	54		58
Foreign government [Member]
Assets:
Total AFS securities	254		260
Foreign government [Member] | Level 1 [Member]
Assets:
Total AFS securities
Foreign government [Member] | Level 2 [Member]
Assets:
Total AFS securities	254		260
Foreign government [Member] | Level 3 [Member]
Assets:
Total AFS securities
Residential Mortgage Backed Securities [Member]
Assets:
Total AFS securities	4,262		4,204
Residential Mortgage Backed Securities [Member] | Level 1 [Member]
Assets:
Total AFS securities
Residential Mortgage Backed Securities [Member] | Level 2 [Member]
Assets:
Total AFS securities	3,908		3,833
Residential Mortgage Backed Securities [Member] | Level 3 [Member]
Assets:
Total AFS securities	354		371
Commercial Mortgage Backed Securities [Member]
Assets:
Total AFS securities	2,859		2,918
Commercial Mortgage Backed Securities [Member] | Level 1 [Member]
Assets:
Total AFS securities
Commercial Mortgage Backed Securities [Member] | Level 2 [Member]
Assets:
Total AFS securities	2,829		2,896
Commercial Mortgage Backed Securities [Member] | Level 3 [Member]
Assets:
Total AFS securities	30		22
Asset-backed Securities [Member]
Assets:
Total AFS securities	2,014		1,640
Asset-backed Securities [Member] | Level 1 [Member]
Assets:
Total AFS securities
Asset-backed Securities [Member] | Level 2 [Member]
Assets:
Total AFS securities	1,769		1,387
Asset-backed Securities [Member] | Level 3 [Member]
Assets:
Total AFS securities	245		253
All other corporate [Member]
Assets:
Total AFS securities	10,400		10,240
All other corporate [Member] | Level 1 [Member]
Assets:
Total AFS securities	5		5
All other corporate [Member] | Level 2 [Member]
Assets:
Total AFS securities	10,151		9,999
All other corporate [Member] | Level 3 [Member]
Assets:
Total AFS securities	244		236
Equity securities [Member]
Assets:
Total AFS securities	1,065		939
Equity securities [Member] | Level 1 [Member]
Assets:
Total AFS securities	881		781
Equity securities [Member] | Level 2 [Member]
Assets:
Total AFS securities	135		121
Equity securities [Member] | Level 3 [Member]
Assets:
Total AFS securities	49		37
Variable Annuity Assets (separate accounts) [Member]
Assets:
Variable annuity assets	614	[1]	580	[1]
Variable Annuity Assets (separate accounts) [Member] | Level 1 [Member]
Assets:
Variable annuity assets		[1]		[1]
Variable Annuity Assets (separate accounts) [Member] | Level 2 [Member]
Assets:
Variable annuity assets	614	[1]	580	[1]
Variable Annuity Assets (separate accounts) [Member] | Level 3 [Member]
Assets:
Variable annuity assets		[1]		[1]
Other Investments [Member]
Assets:
Other Investments	195		133
Other Investments [Member] | Level 1 [Member]
Assets:
Other Investments
Other Investments [Member] | Level 2 [Member]
Assets:
Other Investments	195		133
Other Investments [Member] | Level 3 [Member]
Assets:
Other Investments

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