Investments (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Fixed Income Securities [Member]
Accumulated other comprehensive income (loss)
Beginning of period	$ 298,096	$ 114,515	$ 284,338	$ 118,498
Change in unrealized investment gains and losses	61,869	53,217	75,867	52,976
Reclassification of net realized investment (gains) losses to net income	(3,861)	(3,765)	(4,101)	(7,507)
End of period	356,104	163,967	356,104	163,967
Equity Securities [Member]
Accumulated other comprehensive income (loss)
Beginning of period	2,238	2,497	2,408	2,139
Change in unrealized investment gains and losses	882	391	727	749
Reclassification of net realized investment (gains) losses to net income	(2,577)	(3)	(2,592)	(3)
End of period	$ 543	$ 2,885	$ 543	$ 2,885