Investments (Schedule of Net Investment Income) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Net investment income	$ 52,368	$ 65,594	$ 102,576	$ 134,496
Fixed Maturity Investments [Member]
Net investment income	50,648	67,552	101,594	138,650
Equity Securities and Other Invested Assets [Member]
Net investment income	5,015	940	7,211	1,246
Cash and Cash Equivalents [Member]
Net investment income	127	111	445	163
Expenses [Member]
Net investment income	$ (3,422)	$ (3,009)	$ (6,674)	$ (5,563)