Investments and Derivative Instruments (Details Textual 1) (USD $)																																			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 International Program Hedging Instruments [Member]	Dec. 31, 2011 International Program Hedging Instruments [Member]	Sep. 30, 2012 Standard Market Indices of Diversified Portfolios [Member] Basket Credit Default Swaps [Member]	Dec. 31, 2011 Standard Market Indices of Diversified Portfolios [Member] Basket Credit Default Swaps [Member]	Sep. 30, 2012 Customized Diversified Portfolios [Member] Basket Credit Default Swaps [Member]	Dec. 31, 2011 Customized Diversified Portfolios [Member] Basket Credit Default Swaps [Member]	Sep. 30, 2012 International [Member]	Dec. 31, 2011 International [Member]	Sep. 30, 2012 International [Member] Long Hedge Position [Member]	Dec. 31, 2011 International [Member] Long Hedge Position [Member]	Sep. 30, 2012 International [Member] Short Hedge Position [Member] Macro Hedge Program [Member]	Dec. 31, 2011 International [Member] Short Hedge Position [Member] Macro Hedge Program [Member]	Sep. 30, 2012 Currency Options [Member] International Program Hedging Instruments [Member]	Dec. 31, 2011 Currency Options [Member] International Program Hedging Instruments [Member]	Sep. 30, 2012 Currency Forwards [Member] International Program Hedging Instruments [Member]		Dec. 31, 2011 Currency Forwards [Member] International Program Hedging Instruments [Member]		Sep. 30, 2012 Currency Forwards [Member] Net Hedge Position [Member] International Program Hedging Instruments [Member]	Dec. 31, 2011 Currency Forwards [Member] Net Hedge Position [Member] International Program Hedging Instruments [Member]	Sep. 30, 2012 Currency Forwards [Member] Long Hedge Position [Member] International Program Hedging Instruments [Member]	Dec. 31, 2011 Currency Forwards [Member] Long Hedge Position [Member] International Program Hedging Instruments [Member]	Sep. 30, 2012 Currency Forwards [Member] Short Hedge Position [Member] International Program Hedging Instruments [Member]	Dec. 31, 2011 Currency Forwards [Member] Short Hedge Position [Member] International Program Hedging Instruments [Member]	Sep. 30, 2012 Equity Swap [Member] International Program Hedging Instruments [Member]		Dec. 31, 2011 Equity Swap [Member] International Program Hedging Instruments [Member]		Sep. 30, 2012 Equity Swap [Member] Net Hedge Position [Member] International Program Hedging Instruments [Member]	Sep. 30, 2012 Equity Swap [Member] Long Hedge Position [Member] International Program Hedging Instruments [Member]	Sep. 30, 2012 Equity Swap [Member] Short Hedge Position [Member] International Program Hedging Instruments [Member]	Dec. 31, 2011 Equity Swap [Member] Short Hedge Position [Member] International Program Hedging Instruments [Member]	Sep. 30, 2012 Japan 3Win Related Foreign Currency Swaps [Member] JAPAN	Sep. 30, 2011 Japan 3Win Related Foreign Currency Swaps [Member] JAPAN	Sep. 30, 2012 Japan 3Win Related Foreign Currency Swaps [Member] JAPAN	Sep. 30, 2011 Japan 3Win Related Foreign Currency Swaps [Member] JAPAN	Sep. 30, 2012 Fixed annuity hedging instruments [Member] JAPAN	Sep. 30, 2011 Fixed annuity hedging instruments [Member] JAPAN	Sep. 30, 2012 Fixed annuity hedging instruments [Member] JAPAN	Sep. 30, 2011 Fixed annuity hedging instruments [Member] JAPAN
Derivative [Line Items]
Associated liability adjusted for changes in spot rates through realized capital gain																																			$ (46,000,000)	$ (93,000,000)	$ 19,000,000	$ (100,000,000)	$ (54,000,000)	$ (115,000,000)	$ 33,000,000	$ (125,000,000)
Notional Amount	213,672,000,000	196,608,000,000	52,177,000,000	28,719,000,000					47,200,000,000	28,000,000,000	5,000,000,000	700,000,000	42,200,000,000	27,300,000,000	9,088,000,000	7,038,000,000	10,148,000,000	[1]	8,622,000,000	[1]	1,900,000,000	7,200,000,000	6,000,000,000	7,900,000,000	4,100,000,000	700,000,000	2,588,000,000	[2]	392,000,000	[2]	800,000,000	1,700,000,000	900,000,000	400,000,000
Amount of standard market indices of diversified portfolios of corporate issuers					2,600,000,000	2,700,000,000
Amount of customized diversified portfolios of corporate issuers							353,000,000	478,000,000
Notional Amount of Interest Rate Fair Value Hedge Derivatives	$ 5,100,000,000	$ 5,100,000,000

[1] As of September 30, 2012 and December 31, 2011 net notional amounts are $1.9 billion and $7.2 billion, respectively, which include $6.0 billion and $7.9 billion, respectively, related to long positions and $4.1 billion and $0.7 billion, respectively, related to short positions.

[2] As of September 30, 2012 the net notional amount is $0.8 billion which includes $1.7 billion related to long positions and $0.9 billion related to short positions. As of December 31, 2011 the net notional amount of $0.4 billion related to long positions only.