Fair Value of Assets and Liabilities (Details 3) (USD $)	3 Months Ended		12 Months Ended	3 Months Ended					3 Months Ended															3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Fixed income securities	Mar. 31, 2012 Fixed income securities	Mar. 31, 2013 Municipal	Mar. 31, 2012 Municipal	Dec. 31, 2011 Municipal	Mar. 31, 2013 Corporate	Mar. 31, 2012 Corporate	Mar. 31, 2013 ABS	Mar. 31, 2012 ABS	Mar. 31, 2012 RMBS	Mar. 31, 2013 CMBS	Mar. 31, 2012 CMBS	Mar. 31, 2013 Redeemable preferred stock	Dec. 31, 2012 Redeemable preferred stock	Mar. 31, 2012 Redeemable preferred stock	Dec. 31, 2011 Redeemable preferred stock	Mar. 31, 2013 Equity securities	Dec. 31, 2012 Equity securities	Mar. 31, 2012 Equity securities	Dec. 31, 2011 Equity securities	Mar. 31, 2013 Free-standing derivatives, net	Mar. 31, 2012 Free-standing derivatives, net	Mar. 31, 2013 Other assets	Dec. 31, 2012 Other assets	Mar. 31, 2012 Other assets	Dec. 31, 2011 Other assets
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	$ 2,041,000,000	$ 1,965,000,000	$ 1,965,000,000	$ 2,060,000,000	$ 2,038,000,000	$ 338,000,000	$ 387,000,000	$ 387,000,000	$ 1,501,000,000	$ 1,319,000,000	$ 199,000,000	$ 254,000,000	$ 47,000,000	$ 21,000,000	$ 30,000,000	$ 1,000,000	$ 1,000,000	$ 1,000,000	$ 1,000,000	$ 7,000,000	$ 7,000,000	$ 14,000,000	$ 14,000,000	$ (27,000,000)	$ (88,000,000)	$ 1,000,000	$ 1,000,000	$ 1,000,000	$ 1,000,000
Total gains (losses) included in: net income	7,000,000	32,000,000			17,000,000	(12,000,000)			12,000,000	5,000,000		13,000,000			(1,000,000)									7,000,000	15,000,000
Total gains (losses) included in: OCI	33,000,000	45,000,000		33,000,000	45,000,000	26,000,000			(2,000,000)	26,000,000	7,000,000	13,000,000		2,000,000	6,000,000
Transfers into Level 3	42,000,000	56,000,000		42,000,000	56,000,000				25,000,000	56,000,000	17,000,000
Transfers out of Level 3	(125,000,000)	(57,000,000)		(125,000,000)	(57,000,000)				(125,000,000)	(10,000,000)			(47,000,000)
Purchases	73,000,000	22,000,000		72,000,000	19,000,000				72,000,000	19,000,000														1,000,000	3,000,000
Sales	(235,000,000)	(54,000,000)		(235,000,000)	(54,000,000)	(101,000,000)			(109,000,000)	(54,000,000)	(8,000,000)			(17,000,000)
Settlements	(16,000,000)	(50,000,000)		(15,000,000)	(50,000,000)				(11,000,000)	(32,000,000)	(4,000,000)	(3,000,000)			(15,000,000)									(1,000,000)
Balance at end of period	1,820,000,000	1,959,000,000	2,041,000,000	1,832,000,000	2,014,000,000	251,000,000	387,000,000	387,000,000	1,363,000,000	1,329,000,000	211,000,000	277,000,000		6,000,000	20,000,000	1,000,000	1,000,000	1,000,000	1,000,000	7,000,000	7,000,000	14,000,000	14,000,000	(20,000,000)	(70,000,000)	1,000,000	1,000,000	1,000,000	1,000,000
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	13,000,000		7,000,000
Effect to net income included in realized capital gains and losses	2,000,000		26,000,000
Effect to net income included in investment income	5,000,000		6,000,000
Effect to net income included in interest credited to contract holder funds	(20,000,000)		(56,000,000)
Effect to net income included in contract benefits	26,000,000		31,000,000
Free-standing derivatives, assets	4,000,000		2,000,000
Free-standing derivatives, liabilities	24,000,000		72,000,000
Assets transferred between Level 1 and Level 2	0		0
Liabilities transferred between Level 1 and Level 2	$ 0		$ 0