Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Liabilities of Managed Investment Entities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial liabilities, Beginning Balance	$ (2,593)	$ (2,258)
Total realized/unrealized Gains (losses) included in Net income	(84)	(62)
Purchases and issuances	(366)
Sales and settlements	489	4
Financial liabilities, Ending Balance	(2,554)	(2,316)
Embedded derivatives [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial liabilities, Beginning Balance	(395)	(190)
Total realized/unrealized Gains (losses) included in Net income	(62)	(19)
Purchases and issuances	(34)	(30)
Sales and settlements	8	5
Financial liabilities, Ending Balance	(483)	(234)
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	83	20
Total realized/unrealized gains (losses) included in Net income
Total realized/unrealized gains (losses) included in Other comprehensive income loss		1
Purchases and issuances	10
Transfer out of Level 3	(21)
Financial assets, Ending Balance	72	21
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	361	312
Total realized/unrealized gains (losses) included in Net income	1	1
Total realized/unrealized gains (losses) included in Other comprehensive income loss
Purchases and issuances	8
Sales and settlements	(10)	(13)
Transfer into Level 3	60	7
Transfer out of Level 3	(106)	(36)
Financial assets, Ending Balance	314	271
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	19	6
Total realized/unrealized gains (losses) included in Other comprehensive income loss	1
Transfer into Level 3		3
Financial assets, Ending Balance	20	9
Assets of Managed Investment Entities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	44	48
Total realized/unrealized gains (losses) included in Net income		(1)
Purchases and issuances	12	7
Sales and settlements	(3)	(4)
Transfer into Level 3	14	6
Transfer out of Level 3	(3)	(2)
Financial assets, Ending Balance	64	54
All other corporate [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	519	436
Total realized/unrealized gains (losses) included in Net income	2	(2)
Total realized/unrealized gains (losses) included in Other comprehensive income loss	3
Purchases and issuances	26	45
Sales and settlements	(16)	(11)
Transfer into Level 3	21	22
Transfer out of Level 3	(40)	(66)
Financial assets, Ending Balance	515	424
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	11	21
Total realized/unrealized gains (losses) included in Other comprehensive income loss		2
Purchases and issuances	9
Sales and settlements		(2)
Transfer into Level 3	4
Financial assets, Ending Balance	24	21
Trading fixed maturities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	1	3
Total realized/unrealized gains (losses) included in Net income
Total realized/unrealized gains (losses) included in Other comprehensive income loss
Transfer out of Level 3		(2)
Financial assets, Ending Balance	$ 1	$ 1