Investments and Derivative Instruments (Details Textual 1) (USD $)																									3 Months Ended
	Dec. 31, 2012	Mar. 31, 2013 International Program Hedging Instruments [Member]	Dec. 31, 2012 International Program Hedging Instruments [Member]	Mar. 31, 2013 Standard Market Indices of Diversified Portfolios [Member] Basket Credit Default Swaps [Member]	Dec. 31, 2012 Standard Market Indices of Diversified Portfolios [Member] Basket Credit Default Swaps [Member]	Dec. 31, 2012 Customized Diversified Portfolios [Member] Basket Credit Default Swaps [Member]	Mar. 31, 2013 International [Member]	Dec. 31, 2012 International [Member]	Mar. 31, 2013 International [Member] Long Hedge Position [Member]	Dec. 31, 2012 International [Member] Long Hedge Position [Member]	Mar. 31, 2013 International [Member] Short Hedge Position [Member] Macro Hedge Program [Member]	Dec. 31, 2012 International [Member] Short Hedge Position [Member] Macro Hedge Program [Member]	Mar. 31, 2013 Currency Options [Member] International Program Hedging Instruments [Member]	Dec. 31, 2012 Currency Options [Member] International Program Hedging Instruments [Member]	Mar. 31, 2013 Currency Forwards [Member] International Program Hedging Instruments [Member]	Dec. 31, 2012 Currency Forwards [Member] International Program Hedging Instruments [Member]	Mar. 31, 2013 Currency Forwards [Member] Net Hedge Position [Member] International Program Hedging Instruments [Member]	Dec. 31, 2012 Currency Forwards [Member] Net Hedge Position [Member] International Program Hedging Instruments [Member]	Mar. 31, 2013 Currency Forwards [Member] Long Hedge Position [Member] International Program Hedging Instruments [Member]	Dec. 31, 2012 Currency Forwards [Member] Long Hedge Position [Member] International Program Hedging Instruments [Member]	Mar. 31, 2013 Currency Forwards [Member] Short Hedge Position [Member] International Program Hedging Instruments [Member]	Dec. 31, 2012 Currency Forwards [Member] Short Hedge Position [Member] International Program Hedging Instruments [Member]	Mar. 31, 2013 Equity Swap [Member] International Program Hedging Instruments [Member]	Dec. 31, 2012 Equity Swap [Member] International Program Hedging Instruments [Member]	Mar. 31, 2013 Japan 3Win Related Foreign Currency Swaps [Member] JAPAN	Mar. 31, 2012 Japan 3Win Related Foreign Currency Swaps [Member] JAPAN	Mar. 31, 2013 Fixed annuity hedging instruments [Member] JAPAN	Mar. 31, 2012 Fixed annuity hedging instruments [Member] JAPAN
Derivative [Line Items]
Associated liability adjusted for changes in spot rates through realized capital gain																									$ 116,000,000	$ 118,000,000	$ 151,000,000	$ 157,000,000
Notional Amount		52,723,000,000	48,448,000,000				49,300,000,000	43,800,000,000	3,400,000,000	4,600,000,000	45,900,000,000	39,200,000,000	11,845,000,000	9,710,000,000	8,458,000,000	9,327,000,000	2,300,000,000	100,000,000	5,700,000,000	4,700,000,000	3,400,000,000	4,600,000,000	4,131,000,000	2,683,000,000
Amount of standard market indices of diversified portfolios of corporate issuers				2,600,000,000	2,400,000,000
Amount of customized diversified portfolios of corporate issuers						478,000,000
Notional Amount of Interest Rate Fair Value Hedge Derivatives	$ 5,100,000,000