Investments (Details 9) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	$ 437,391,000	$ 350,490,000
Investment Income Investment Expense	12,260,000	9,550,000
Investment income, net of related expenses	425,131,000	340,940,000
Availableforsale Securities Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	239,244,000	191,418,000
Mortgage Loans On Real Estate Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	28,243,000	14,965,000
Policy Loans Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	17,910,000	16,783,000
Funds Withheld At Interest [Member]
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	137,259,000	115,014,000
Short Term Investments Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	813,000	988,000
Other Aggregated Investments Member
Major Categories Of Investment Income Net of Expenses [Line Items]
Investment Revenue	$ 13,922,000	$ 11,322,000