Investments (Details 1) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	$ 344,442	$ 297,407	$ 722,792	$ 607,887
Investment Income Investment Expense	7,006	5,736	14,316	11,958
Investment income, net of related expenses	337,436	291,671	708,476	595,929
Availableforsale Securities Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	191,030	175,638	375,591	353,130
Mortgage Loans On Real Estate Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	13,593	11,954	27,328	24,160
Policy Loans Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	16,724	18,037	33,095	37,879
Funds Withheld At Interest Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	111,700	84,392	264,760	175,573
Short Term Investments Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	883	1,130	1,808	2,378
Other Aggregated Investments Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	$ 10,512	$ 6,256	$ 20,210	$ 14,767