Fair Value Measurements (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Fixed Maturities [Member] | Available-for-sale Securities [Member]
Roll Forward of Financial Instruments (Assets) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)
Fair value, Begging Balance	$ 5,121	$ 7,489
Total realized/unrealized gains (losses) included in net income	1	(53)
Total realized/unrealized gains (losses) included in OCI	120	279
Purchases	445	19
Settlements	(131)	(122)
Sales	(102)	(213)
Transfers into Level 3	1,135	362
Transfers out of Level 3	(603)	(341)
Fair value, Ending Balance	5,986	7,420
Changes in unrealized gains (losses) included in net income related to financial instruments still held at March 31, 2011	(11)	(41)
Fixed Maturities [Member] | Available-for-sale Securities [Member] | ABS [Member]
Roll Forward of Financial Instruments (Assets) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)
Fair value, Begging Balance	361	477
Total realized/unrealized gains (losses) included in net income		(5)
Total realized/unrealized gains (losses) included in OCI	9	20
Settlements	(35)	(11)
Sales	(12)
Transfers into Level 3		49
Transfers out of Level 3	(24)	(84)
Fair value, Ending Balance	299	446
Changes in unrealized gains (losses) included in net income related to financial instruments still held at March 31, 2011		(5)
Fixed Maturities [Member] | Available-for-sale Securities [Member] | CDOs [Member]
Roll Forward of Financial Instruments (Assets) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)
Fair value, Begging Balance	368	2,581
Total realized/unrealized gains (losses) included in net income	2	(15)
Total realized/unrealized gains (losses) included in OCI	63	113
Settlements	(10)	(35)
Sales	(3)
Transfers into Level 3	483	30
Fair value, Ending Balance	903	2,674
Changes in unrealized gains (losses) included in net income related to financial instruments still held at March 31, 2011		(15)
Fixed Maturities [Member] | Available-for-sale Securities [Member] | CMBS [Member]
Roll Forward of Financial Instruments (Assets) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)
Fair value, Begging Balance	588	689
Total realized/unrealized gains (losses) included in net income	(5)	(2)
Total realized/unrealized gains (losses) included in OCI	23	113
Purchases	12
Settlements	(32)	(10)
Sales		(122)
Transfers into Level 3	450	73
Transfers out of Level 3	(35)
Fair value, Ending Balance	1,001	741
Changes in unrealized gains (losses) included in net income related to financial instruments still held at March 31, 2011	(5)	(1)
Fixed Maturities [Member] | Available-for-sale Securities [Member] | Corporate [Member]
Roll Forward of Financial Instruments (Assets) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)
Fair value, Begging Balance	2,255	2,129
Total realized/unrealized gains (losses) included in net income	(3)	(22)
Total realized/unrealized gains (losses) included in OCI	10	(8)
Purchases	134	17
Settlements	(20)	(31)
Sales	(53)	(73)
Transfers into Level 3	202	195
Transfers out of Level 3	(531)	(111)
Fair value, Ending Balance	1,994	2,096
Changes in unrealized gains (losses) included in net income related to financial instruments still held at March 31, 2011		(17)
Fixed Maturities [Member] | Available-for-sale Securities [Member] | Foreign govt./govt. agencies [Member]
Roll Forward of Financial Instruments (Assets) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)
Fair value, Begging Balance	49	56
Purchases	7	2
Settlements	(1)	(1)
Sales		(2)
Transfers into Level 3		11
Transfers out of Level 3		(3)
Fair value, Ending Balance	55	63
Fixed Maturities [Member] | Available-for-sale Securities [Member] | Municipal [Member]
Roll Forward of Financial Instruments (Assets) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)
Fair value, Begging Balance	437	272
Total realized/unrealized gains (losses) included in OCI	(11)
Purchases	212
Transfers into Level 3		4
Transfers out of Level 3	(13)
Fair value, Ending Balance	625	276
Fixed Maturities [Member] | Available-for-sale Securities [Member] | RMBS [Member]
Roll Forward of Financial Instruments (Assets) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)
Fair value, Begging Balance	1,063	1,285
Total realized/unrealized gains (losses) included in net income	7	(9)
Total realized/unrealized gains (losses) included in OCI	26	41
Purchases	80
Settlements	(33)	(34)
Sales	(34)	(16)
Transfers out of Level 3		(143)
Fair value, Ending Balance	1,109	1,124
Changes in unrealized gains (losses) included in net income related to financial instruments still held at March 31, 2011	(6)	(3)
Fixed Maturities, FVO [Member]
Roll Forward of Financial Instruments (Assets) Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3)
Fair value, Begging Balance	495	522
Total realized/unrealized gains (losses) included in net income	27	58
Settlements		(1)
Sales	(14)
Fair value, Ending Balance	508	579
Changes in unrealized gains (losses) included in net income related to financial instruments still held at March 31, 2011	$ 18	$ 58