Derivative Instruments (Details 4) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	$ 27,388	$ 22,992	$ 151,008	$ 154,177
Policy Acquisition Costs And Other Insurance Expenses	261,282	237,149	592,435	603,451
Interest credited	96,196	79,169	202,259	136,103
Interest Rate Swap Member
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	25,343	87,115	14,613	98,455
Future Member
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	(2,873)	32,823	(14,296)	21,077
Foreign Exchange Forward Member
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	595	1,447	(260)	618
Consumer Price Index Swap Member
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	503	108	1,315	1,032
Credit Default Swap Member
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	988	(4,060)	1,880	(3,284)
Equity Member
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	3,919	127	(650)	127
Embedded Derivatives In Modified Coinsurance Or Funds Withheld Arrangements Member
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	10,525	32,512	101,060	155,147
Embedded Derivatives In Indexed Annuity Member
Income Affect Of Non Hedging Derivatives [Line Items]
Policy Acquisition Costs And Other Insurance Expenses	4,026	2,596	12,119	1,161
Interest credited	(36,101)	(17,546)	(85,466)	(4,383)
Embedded Derivatives In Variable Annuity Member
Income Affect Of Non Hedging Derivatives [Line Items]
Total investment related gains (losses), net	$ (25,860)	$ (140,934)	$ 6,794	$ (133,763)