Liability for Unpaid Loss and Loss Adjustment Expenses (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of net prior year reserve development
(Favorable) Unfavorable	$ 9,038	$ 13,369	$ 356
E & S Lines [Member]
Summary of net prior year reserve development
(Favorable) Unfavorable	(1,780)	(10,209)	(2,397)
Alternative Risk Transfer [Member]
Summary of net prior year reserve development
(Favorable) Unfavorable	2,946	12,120	2,666
Assumed Re [Member]
Summary of net prior year reserve development
(Favorable) Unfavorable	8,096	9,437	1,448
Runoff [Member]
Summary of net prior year reserve development
(Favorable) Unfavorable	$ (224)	$ 2,021	$ (1,361)