Fair Value of Assets and Liabilities (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	$ 3,095	$ 9,102	$ 10,171
Total gains (losses) included in: net income	27	(189)	(829)
Total gains (losses) included in: OCI	223	165	1,769
Transfers into Level 3	491	395	589
Transfers out of Level 3	(253)	(4,974)	(1,828)
Purchases	703	997
Sales	(1,056)	(1,840)
Settlements	(188)	(561)
Purchases, sales, issuances and settlements, net			(770)
Balance at end of period	3,042	3,095	9,102
Fair value assets and liabilities measured on recurring basis, gain (loss) included in earnings
Total realized and unrealized gains (losses) included in net income, recurring Level 3 assets and liabilities	195	(323)	(860)
Effect to net income included in realized capital gains and losses		(221)	(901)
Effect to net income included in investment income	27	36	73
Effect to net income included in interest credited to contract holder funds	132	(106)	(1)
Effect to net income included in life and annuity contract benefits	36	(32)	(31)
Free-standing derivatives, assets	3	1	74
Free-standing derivatives, liabilities	30	96	95
Fixed income securities
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	3,146	9,059	10,045
Total gains (losses) included in: net income	7	(88)	(634)
Total gains (losses) included in: OCI	214	165	1,764
Transfers into Level 3	491	395	589
Transfers out of Level 3	(253)	(4,964)	(1,821)
Purchases	512	926
Sales	(1,018)	(1,839)
Settlements	(202)	(508)
Purchases, sales, issuances and settlements, net			(884)
Balance at end of period	2,897	3,146	9,059
U.S. government and agencies
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Transfers into Level 3	8
Balance at end of period	8
Municipal
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	1,332	2,016	2,706
Total gains (losses) included in: net income	(35)	(44)	(40)
Total gains (losses) included in: OCI	76	54	46
Transfers into Level 3	53	70	38
Transfers out of Level 3	(28)	(82)	(146)
Purchases	46	14
Sales	(463)	(689)
Settlements	(16)	(7)
Purchases, sales, issuances and settlements, net			(588)
Balance at end of period	965	1,332	2,016
Corporate
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	1,405	1,908	2,241
Total gains (losses) included in: net income	20	62	5
Total gains (losses) included in: OCI	68	(44)	115
Transfers into Level 3	387	239	444
Transfers out of Level 3	(92)	(523)	(730)
Purchases	276	387
Sales	(310)	(537)
Settlements	(137)	(87)
Purchases, sales, issuances and settlements, net			(167)
Balance at end of period	1,617	1,405	1,908
Foreign government
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period			20
Purchases, sales, issuances and settlements, net			(20)
Asset-backed securities ("ABS")
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	297	2,417	2,001
Total gains (losses) included in: net income	26	23	55
Total gains (losses) included in: OCI	61	(65)	275
Transfers into Level 3	43
Transfers out of Level 3	(81)	(2,137)	(467)
Purchases	155	504
Sales	(217)	(169)
Settlements	(33)	(276)
Purchases, sales, issuances and settlements, net			553
Balance at end of period	251	297	2,417
Residential mortgage-backed securities ("RMBS")
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	51	1,794	1,671
Total gains (losses) included in: net income		(86)	(421)
Total gains (losses) included in: OCI		107	736
Transfers out of Level 3	(47)	(1,256)	(57)
Purchases		4
Sales		(378)
Settlements	(1)	(134)
Purchases, sales, issuances and settlements, net			(135)
Balance at end of period	3	51	1,794
Commercial mortgage-backed securities ("CMBS")
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	60	923	1,404
Total gains (losses) included in: net income	(4)	(43)	(233)
Total gains (losses) included in: OCI	9	113	592
Transfers into Level 3		86	107
Transfers out of Level 3	(5)	(966)	(421)
Purchases	34	17
Sales	(27)	(66)
Settlements	(15)	(4)
Purchases, sales, issuances and settlements, net			(526)
Balance at end of period	52	60	923
Redeemable preferred stock
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	1		2
Purchases	1
Sales	(1)
Purchases, sales, issuances and settlements, net			(1)
Balance at end of period	1		1
Equity securities
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	43	63	69
Total gains (losses) included in: net income	(7)	(10)	8
Total gains (losses) included in: OCI	9		5
Transfers out of Level 3		(10)	(7)
Purchases	164	1
Sales	(38)	(1)
Purchases, sales, issuances and settlements, net			(12)
Balance at end of period	171	43	63
Free-standing derivatives, net
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period	(95)	(21)	55
Total gains (losses) included in: net income	27	(91)	(202)
Purchases	27	70
Settlements	14	(53)
Purchases, sales, issuances and settlements, net			126
Balance at end of period	(27)	(95)	(21)
Other assets
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation Calculation Rollforward
Balance at beginning of period			2
Total gains (losses) included in: net income			(1)
Balance at end of period	$ 1	$ 1	$ 1